Red Hat Enterprise Linux 9
Configuring and managing networking
Managing network interfaces and advanced networking features
Last Updated: 2024-09-04
Red Hat Enterprise Linux 9 Configuring and managing networking
Managing network interfaces and advanced networking features
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Abstract
Using the networking capabilities of Red Hat Enterprise Linux (RHEL), you can configure your host
to meet your organization's network and security requirements. For example: You can configure
bonds, VLANs, bridges, tunnels and other network types to connect the host to the network. IPSec
and WireGuard provide secure VPNs between hosts and networks. RHEL also supports advanced
networking features, such as policy-based routing and Multipath TCP (MPTCP).
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Table of Contents
PROVIDING FEEDBACK ON RED HAT DOCUMENTATION
CHAPTER 1. IMPLEMENTING CONSISTENT NETWORK INTERFACE NAMING
1.1. HOW THE UDEV DEVICE MANAGER RENAMES NETWORK INTERFACES
1.2. NETWORK INTERFACE NAMING POLICIES
1.3. NETWORK INTERFACE NAMING SCHEMES
1.4. SWITCHING TO A DIFFERENT NETWORK INTERFACE NAMING SCHEME
1.5. CUSTOMIZING THE PREFIX FOR ETHERNET INTERFACES DURING INSTALLATION
1.6. CONFIGURING USER-DEFINED NETWORK INTERFACE NAMES BY USING UDEV RULES
1.7. CONFIGURING USER-DEFINED NETWORK INTERFACE NAMES BY USING SYSTEMD LINK FILES
1.8. ASSIGNING ALTERNATIVE NAMES TO A NETWORK INTERFACE BY USING SYSTEMD LINK FILES
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
2.1. CONFIGURING AN ETHERNET CONNECTION BY USING NMCLI
2.2. CONFIGURING AN ETHERNET CONNECTION BY USING THE NMCLI INTERACTIVE EDITOR
2.3. CONFIGURING AN ETHERNET CONNECTION BY USING NMTUI
2.4. CONFIGURING AN ETHERNET CONNECTION BY USING CONTROL-CENTER
2.5. CONFIGURING AN ETHERNET CONNECTION BY USING NM-CONNECTION-EDITOR
2.6. CONFIGURING AN ETHERNET CONNECTION WITH A STATIC IP ADDRESS BY USING NMSTATECTL
2.7. CONFIGURING AN ETHERNET CONNECTION WITH A STATIC IP ADDRESS BY USING THE NETWORK
RHEL SYSTEM ROLE WITH AN INTERFACE NAME
2.8. CONFIGURING AN ETHERNET CONNECTION WITH A STATIC IP ADDRESS BY USING THE NETWORK
RHEL SYSTEM ROLE WITH A DEVICE PATH
2.9. CONFIGURING AN ETHERNET CONNECTION WITH A DYNAMIC IP ADDRESS BY USING NMSTATECTL
2.10. CONFIGURING AN ETHERNET CONNECTION WITH A DYNAMIC IP ADDRESS BY USING THE NETWORK
RHEL SYSTEM ROLE WITH AN INTERFACE NAME
2.11. CONFIGURING AN ETHERNET CONNECTION WITH A DYNAMIC IP ADDRESS BY USING THE NETWORK
RHEL SYSTEM ROLE WITH A DEVICE PATH
2.12. CONFIGURING MULTIPLE ETHERNET INTERFACES BY USING A SINGLE CONNECTION PROFILE BY
INTERFACE NAME
2.13. CONFIGURING A SINGLE CONNECTION PROFILE FOR MULTIPLE ETHERNET INTERFACES USING PCI
IDS
CHAPTER 3. CONFIGURING A NETWORK BOND
3.1. UNDERSTANDING THE DEFAULT BEHAVIOR OF CONTROLLER AND PORT INTERFACES
3.2. UPSTREAM SWITCH CONFIGURATION DEPENDING ON THE BONDING MODES
3.3. CONFIGURING A NETWORK BOND BY USING NMCLI
3.4. CONFIGURING A NETWORK BOND BY USING THE RHEL WEB CONSOLE
3.5. CONFIGURING A NETWORK BOND BY USING NMTUI
3.6. CONFIGURING A NETWORK BOND BY USING NM-CONNECTION-EDITOR
3.7. CONFIGURING A NETWORK BOND BY USING NMSTATECTL
3.8. CONFIGURING A NETWORK BOND BY USING THE NETWORK RHEL SYSTEM ROLE
3.9. CREATING A NETWORK BOND TO ENABLE SWITCHING BETWEEN AN ETHERNET AND WIRELESS
CONNECTION WITHOUT INTERRUPTING THE VPN
3.10. THE DIFFERENT NETWORK BONDING MODES
3.11. THE XMIT_HASH_POLICY BONDING PARAMETER
CHAPTER 4. CONFIGURING A NIC TEAM
4.1. MIGRATING A NIC TEAM CONFIGURATION TO NETWORK BOND
4.2. UNDERSTANDING THE DEFAULT BEHAVIOR OF CONTROLLER AND PORT INTERFACES
4.3. UNDERSTANDING THE TEAMD SERVICE, RUNNERS, AND LINK-WATCHERS
4.4. CONFIGURING A NIC TEAM BY USING NMCLI
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Table of Contents
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4.5. CONFIGURING A NIC TEAM BY USING THE RHEL WEB CONSOLE
4.6. CONFIGURING A NIC TEAM BY USING NM-CONNECTION-EDITOR
CHAPTER 5. CONFIGURING VLAN TAGGING
5.1. CONFIGURING VLAN TAGGING BY USING NMCLI
5.2. CONFIGURING NESTED VLANS BY USING NMCLI
5.3. CONFIGURING VLAN TAGGING BY USING THE RHEL WEB CONSOLE
5.4. CONFIGURING VLAN TAGGING BY USING NMTUI
5.5. CONFIGURING VLAN TAGGING BY USING NM-CONNECTION-EDITOR
5.6. CONFIGURING VLAN TAGGING BY USING NMSTATECTL
5.7. CONFIGURING VLAN TAGGING BY USING THE NETWORK RHEL SYSTEM ROLE
CHAPTER 6. CONFIGURING A NETWORK BRIDGE
6.1. CONFIGURING A NETWORK BRIDGE BY USING NMCLI
6.2. CONFIGURING A NETWORK BRIDGE BY USING THE RHEL WEB CONSOLE
6.3. CONFIGURING A NETWORK BRIDGE BY USING NMTUI
6.4. CONFIGURING A NETWORK BRIDGE BY USING NM-CONNECTION-EDITOR
6.5. CONFIGURING A NETWORK BRIDGE BY USING NMSTATECTL
6.6. CONFIGURING A NETWORK BRIDGE BY USING THE NETWORK RHEL SYSTEM ROLE
CHAPTER 7. SETTING UP AN IPSEC VPN
7.1. CONFIGURING A VPN CONNECTION WITH CONTROL-CENTER
7.2. CONFIGURING A VPN CONNECTION USING NM-CONNECTION-EDITOR
7.3. CONFIGURING AUTOMATIC DETECTION AND USAGE OF ESP HARDWARE OFFLOAD TO ACCELERATE
AN IPSEC CONNECTION
7.4. CONFIGURING ESP HARDWARE OFFLOAD ON A BOND TO ACCELERATE AN IPSEC CONNECTION
7.5. CONFIGURING AN IPSEC BASED VPN CONNECTION BY USING NMSTATECTL
7.5.1. Configuring a host-to-subnet IPSec VPN with PKI authentication and tunnel mode by using nmstatectl
7.5.2. Configuring a host-to-subnet IPSec VPN with RSA authentication and tunnel mode by using nmstatectl
7.5.3. Configuring a host-to-subnet IPSec VPN with PSK authentication and tunnel mode by using nmstatectl
7.5.4. Configuring a host-to-host IPsec VPN with PKI authentication and tunnel mode by using nmstatectl
7.5.5. Configuring a host-to-host IPsec VPN with PSK authentication and transport mode by using nmstatectl
CHAPTER 8. SETTING UP A WIREGUARD VPN
8.1. PROTOCOLS AND PRIMITIVES USED BY WIREGUARD
8.2. HOW WIREGUARD USES TUNNEL IP ADDRESSES, PUBLIC KEYS, AND REMOTE ENDPOINTS
8.3. USING A WIREGUARD CLIENT BEHIND NAT AND FIREWALLS
8.4. CREATING PRIVATE AND PUBLIC KEYS TO BE USED IN WIREGUARD CONNECTIONS
8.5. CONFIGURING A WIREGUARD SERVER BY USING NMCLI
8.6. CONFIGURING A WIREGUARD SERVER BY USING NMTUI
8.7. CONFIGURING A WIREGUARD SERVER BY USING THE RHEL WEB CONSOLE
8.8. CONFIGURING A WIREGUARD SERVER BY USING NM-CONNECTION-EDITOR
8.9. CONFIGURING A WIREGUARD SERVER BY USING THE WG-QUICK SERVICE
8.10. CONFIGURING FIREWALLD ON A WIREGUARD SERVER BY USING THE COMMAND LINE
8.11. CONFIGURING FIREWALLD ON A WIREGUARD SERVER BY USING THE RHEL WEB CONSOLE
8.12. CONFIGURING FIREWALLD ON A WIREGUARD SERVER BY USING THE GRAPHICAL INTERFACE
8.13. CONFIGURING A WIREGUARD CLIENT BY USING NMCLI
8.14. CONFIGURING A WIREGUARD CLIENT BY USING NMTUI
8.15. CONFIGURING A WIREGUARD CLIENT BY USING THE RHEL WEB CONSOLE
8.16. CONFIGURING A WIREGUARD CLIENT BY USING NM-CONNECTION-EDITOR
8.17. CONFIGURING A WIREGUARD CLIENT BY USING THE WG-QUICK SERVICE
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Red Hat Enterprise Linux 9 Configuring and managing networking
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CHAPTER 9. CONFIGURING IP TUNNELS
9.1. CONFIGURING AN IPIP TUNNEL TO ENCAPSULATE IPV4 TRAFFIC IN IPV4 PACKETS
9.2. CONFIGURING A GRE TUNNEL TO ENCAPSULATE LAYER-3 TRAFFIC IN IPV4 PACKETS
9.3. CONFIGURING A GRETAP TUNNEL TO TRANSFER ETHERNET FRAMES OVER IPV4
CHAPTER 10. USING A VXLAN TO CREATE A VIRTUAL LAYER-2 DOMAIN FOR VMS
10.1. BENEFITS OF VXLANS
10.2. CONFIGURING THE ETHERNET INTERFACE ON THE HOSTS
10.3. CREATING A NETWORK BRIDGE WITH A VXLAN ATTACHED
10.4. CREATING A VIRTUAL NETWORK IN LIBVIRT WITH AN EXISTING BRIDGE
10.5. CONFIGURING VIRTUAL MACHINES TO USE VXLAN
CHAPTER 11. MANAGING WIFI CONNECTIONS
11.1. SUPPORTED WIFI SECURITY TYPES
11.2. CONNECTING TO A WIFI NETWORK BY USING NMCLI
11.3. CONNECTING TO A WIFI NETWORK BY USING THE GNOME SYSTEM MENU
11.4. CONNECTING TO A WIFI NETWORK BY USING THE GNOME SETTINGS APPLICATION
11.5. CONFIGURING A WIFI CONNECTION BY USING NMTUI
11.6. CONFIGURING A WIFI CONNECTION BY USING NM-CONNECTION-EDITOR
11.7. CONFIGURING A WIFI CONNECTION WITH 802.1X NETWORK AUTHENTICATION BY USING THE
NETWORK RHEL SYSTEM ROLE
11.8. CONFIGURING A WIFI CONNECTION WITH 802.1X NETWORK AUTHENTICATION IN AN EXISTING
PROFILE BY USING NMCLI
11.9. MANUALLY SETTING THE WIRELESS REGULATORY DOMAIN
CHAPTER 12. CONFIGURING RHEL AS A WPA2 OR WPA3 PERSONAL ACCESS POINT
CHAPTER 13. USING MACSEC TO ENCRYPT LAYER-2 TRAFFIC IN THE SAME PHYSICAL NETWORK
13.1. CONFIGURING A MACSEC CONNECTION BY USING NMCLI
13.2. CONFIGURING A MACSEC CONNECTION USING NMSTATECTL
13.3. ADDITIONAL RESOURCES
CHAPTER 14. GETTING STARTED WITH IPVLAN
14.1. IPVLAN MODES
14.2. COMPARISON OF IPVLAN AND MACVLAN
14.3. CREATING AND CONFIGURING THE IPVLAN DEVICE USING IPROUTE2
CHAPTER 15. CONFIGURING NETWORKMANAGER TO IGNORE CERTAIN DEVICES
15.1. CONFIGURING THE LOOPBACK INTERFACE BY USING NMCLI
15.2. PERMANENTLY CONFIGURING A DEVICE AS UNMANAGED IN NETWORKMANAGER
15.3. TEMPORARILY CONFIGURING A DEVICE AS UNMANAGED IN NETWORKMANAGER
CHAPTER 16. CREATING A DUMMY INTERFACE
16.1. CREATING A DUMMY INTERFACE WITH BOTH AN IPV4 AND IPV6 ADDRESS BY USING NMCLI
CHAPTER 17. USING NETWORKMANAGER TO DISABLE IPV6 FOR A SPECIFIC CONNECTION
17.1. DISABLING IPV6 ON A CONNECTION USING NMCLI
CHAPTER 18. CHANGING A HOSTNAME
18.1. CHANGING A HOSTNAME BY USING NMCLI
18.2. CHANGING A HOSTNAME BY USING HOSTNAMECTL
CHAPTER 19. CONFIGURING NETWORKMANAGER DHCP SETTINGS
19.1. CHANGING THE DHCP CLIENT OF NETWORKMANAGER
19.2. CONFIGURING THE DHCP BEHAVIOR OF A NETWORKMANAGER CONNECTION
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177
180
182
186
186
187
188
189
190
192
192
192
194
195
196
198
200
202
203
205
208
208
210
212
213
213
213
214
216
216
217
218
220
220
221
221
223
223
223
225
225
225
Table of Contents
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CHAPTER 20. RUNNING DHCLIENT EXIT HOOKS USING NETWORKMANAGER A DISPATCHER SCRIPT
20.1. THE CONCEPT OF NETWORKMANAGER DISPATCHER SCRIPTS
20.2. CREATING A NETWORKMANAGER DISPATCHER SCRIPT THAT RUNS DHCLIENT EXIT HOOKS
CHAPTER 21. MANUALLY CONFIGURING THE /ETC/RESOLV.CONF FILE
21.1. DISABLING DNS PROCESSING IN THE NETWORKMANAGER CONFIGURATION
21.2. REPLACING /ETC/RESOLV.CONF WITH A SYMBOLIC LINK TO MANUALLY CONFIGURE DNS SETTINGS
CHAPTER 22. CONFIGURING THE ORDER OF DNS SERVERS
22.1. HOW NETWORKMANAGER ORDERS DNS SERVERS IN /ETC/RESOLV.CONF
Default values of DNS priority parameters
Valid DNS priority values:
22.2. SETTING A NETWORKMANAGER-WIDE DEFAULT DNS SERVER PRIORITY VALUE
22.3. SETTING THE DNS PRIORITY OF A NETWORKMANAGER CONNECTION
CHAPTER 23. USING DIFFERENT DNS SERVERS FOR DIFFERENT DOMAINS
23.1. USING DNSMASQ IN NETWORKMANAGER TO SEND DNS REQUESTS FOR A SPECIFIC DOMAIN TO A
SELECTED DNS SERVER
23.2. USING SYSTEMD-RESOLVED IN NETWORKMANAGER TO SEND DNS REQUESTS FOR A SPECIFIC
DOMAIN TO A SELECTED DNS SERVER
CHAPTER 24. MANAGING THE DEFAULT GATEWAY SETTING
24.1. SETTING THE DEFAULT GATEWAY ON AN EXISTING CONNECTION BY USING NMCLI
24.2. SETTING THE DEFAULT GATEWAY ON AN EXISTING CONNECTION BY USING THE NMCLI
INTERACTIVE MODE
24.3. SETTING THE DEFAULT GATEWAY ON AN EXISTING CONNECTION BY USING NM-CONNECTION-
EDITOR
24.4. SETTING THE DEFAULT GATEWAY ON AN EXISTING CONNECTION BY USING CONTROL-CENTER
24.5. SETTING THE DEFAULT GATEWAY ON AN EXISTING CONNECTION BY USING NMSTATECTL
24.6. SETTING THE DEFAULT GATEWAY ON AN EXISTING CONNECTION BY USING THE NETWORK RHEL
SYSTEM ROLE
24.7. HOW NETWORKMANAGER MANAGES MULTIPLE DEFAULT GATEWAYS
24.8. CONFIGURING NETWORKMANAGER TO AVOID USING A SPECIFIC PROFILE TO PROVIDE A DEFAULT
GATEWAY
24.9. FIXING UNEXPECTED ROUTING BEHAVIOR DUE TO MULTIPLE DEFAULT GATEWAYS
CHAPTER 25. CONFIGURING A STATIC ROUTE
25.1. EXAMPLE OF A NETWORK THAT REQUIRES STATIC ROUTES
25.2. HOW TO USE THE NMCLI UTILITY TO CONFIGURE A STATIC ROUTE
25.3. CONFIGURING A STATIC ROUTE BY USING NMCLI
25.4. CONFIGURING A STATIC ROUTE BY USING NMTUI
25.5. CONFIGURING A STATIC ROUTE BY USING CONTROL-CENTER
25.6. CONFIGURING A STATIC ROUTE BY USING NM-CONNECTION-EDITOR
25.7. CONFIGURING A STATIC ROUTE BY USING THE NMCLI INTERACTIVE MODE
25.8. CONFIGURING A STATIC ROUTE BY USING NMSTATECTL
25.9. CONFIGURING A STATIC ROUTE BY USING THE NETWORK RHEL SYSTEM ROLE
CHAPTER 26. CONFIGURING POLICY-BASED ROUTING TO DEFINE ALTERNATIVE ROUTES
26.1. ROUTING TRAFFIC FROM A SPECIFIC SUBNET TO A DIFFERENT DEFAULT GATEWAY BY USING
NMCLI
26.2. ROUTING TRAFFIC FROM A SPECIFIC SUBNET TO A DIFFERENT DEFAULT GATEWAY BY USING THE
NETWORK RHEL SYSTEM ROLE
CHAPTER 27. REUSING THE SAME IP ADDRESS ON DIFFERENT INTERFACES
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229
229
230
231
231
231
231
232
233
234
234
236
239
239
240
241
243
244
245
247
248
249
251
251
253
254
255
257
259
260
262
263
266
266
269
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Red Hat Enterprise Linux 9 Configuring and managing networking
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27.1. PERMANENTLY REUSING THE SAME IP ADDRESS ON DIFFERENT INTERFACES
27.2. TEMPORARILY REUSING THE SAME IP ADDRESS ON DIFFERENT INTERFACES
27.3. ADDITIONAL RESOURCES
CHAPTER 28. STARTING A SERVICE WITHIN AN ISOLATED VRF NETWORK
28.1. CONFIGURING A VRF DEVICE
28.2. STARTING A SERVICE WITHIN AN ISOLATED VRF NETWORK
CHAPTER 29. CONFIGURING ETHTOOL SETTINGS IN NETWORKMANAGER CONNECTION PROFILES
29.1. CONFIGURING AN ETHTOOL OFFLOAD FEATURE BY USING NMCLI
29.2. CONFIGURING AN ETHTOOL OFFLOAD FEATURE BY USING THE NETWORK RHEL SYSTEM ROLE
29.3. CONFIGURING AN ETHTOOL COALESCE SETTINGS BY USING NMCLI
29.4. CONFIGURING AN ETHTOOL COALESCE SETTINGS BY USING THE NETWORK RHEL SYSTEM ROLE
29.5. INCREASING THE RING BUFFER SIZE TO REDUCE A HIGH PACKET DROP RATE BY USING NMCLI
29.6. INCREASING THE RING BUFFER SIZE TO REDUCE A HIGH PACKET DROP RATE BY USING THE
NETWORK RHEL SYSTEM ROLE
29.7. CONFIGURING AN ETHTOOL CHANNELS SETTINGS BY USING NMCLI
CHAPTER 30. INTRODUCTION TO NETWORKMANAGER DEBUGGING
30.1. INTRODUCTION TO NETWORKMANAGER REAPPLY METHOD
30.2. SETTING THE NETWORKMANAGER LOG LEVEL
30.3. TEMPORARILY SETTING LOG LEVELS AT RUN TIME USING NMCLI
30.4. VIEWING NETWORKMANAGER LOGS
30.5. DEBUGGING LEVELS AND DOMAINS
CHAPTER 31. USING LLDP TO DEBUG NETWORK CONFIGURATION PROBLEMS
31.1. DEBUGGING AN INCORRECT VLAN CONFIGURATION USING LLDP INFORMATION
CHAPTER 32. LINUX TRAFFIC CONTROL
32.1. OVERVIEW OF QUEUING DISCIPLINES
32.2. INTRODUCTION TO CONNECTION TRACKING
32.3. INSPECTING QDISCS OF A NETWORK INTERFACE USING THE TC UTILITY
32.4. UPDATING THE DEFAULT QDISC
32.5. TEMPORARILY SETTING THE CURRENT QDISC OF A NETWORK INTERFACE USING THE TC UTILITY
32.6. PERMANENTLY SETTING THE CURRENT QDISC OF A NETWORK INTERFACE USING
NETWORKMANAGER
32.7. CONFIGURING THE RATE LIMITING OF PACKETS BY USING THE TC-CTINFO UTILITY
32.8. AVAILABLE QDISCS IN RHEL
CHAPTER 33. AUTHENTICATING A RHEL CLIENT TO THE NETWORK BY USING THE 802.1X STANDARD
WITH A CERTIFICATE STORED ON THE FILE SYSTEM
33.1. CONFIGURING 802.1X NETWORK AUTHENTICATION ON AN EXISTING ETHERNET CONNECTION BY
USING NMCLI
33.2. CONFIGURING A STATIC ETHERNET CONNECTION WITH 802.1X NETWORK AUTHENTICATION BY
USING NMSTATECTL
33.3. CONFIGURING A STATIC ETHERNET CONNECTION WITH 802.1X NETWORK AUTHENTICATION BY
USING THE NETWORK RHEL SYSTEM ROLE
33.4. CONFIGURING A WIFI CONNECTION WITH 802.1X NETWORK AUTHENTICATION BY USING THE
NETWORK RHEL SYSTEM ROLE
CHAPTER 34. SETTING UP AN 802.1X NETWORK AUTHENTICATION SERVICE FOR LAN CLIENTS BY USING
HOSTAPD WITH FREERADIUS BACKEND
34.1. PREREQUISITES
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34.2. SETTING UP THE BRIDGE ON THE AUTHENTICATOR
34.3. CERTIFICATE REQUIREMENTS BY FREERADIUS
34.4. CREATING A SET OF CERTIFICATES ON A FREERADIUS SERVER FOR TESTING PURPOSES
34.5. CONFIGURING FREERADIUS TO AUTHENTICATE NETWORK CLIENTS SECURELY BY USING EAP
34.6. CONFIGURING HOSTAPD AS AN AUTHENTICATOR IN A WIRED NETWORK
34.7. TESTING EAP-TTLS AUTHENTICATION AGAINST A FREERADIUS SERVER OR AUTHENTICATOR
34.8. TESTING EAP-TLS AUTHENTICATION AGAINST A FREERADIUS SERVER OR AUTHENTICATOR
34.9. BLOCKING AND ALLOWING TRAFFIC BASED ON HOSTAPD AUTHENTICATION EVENTS
CHAPTER 35. GETTING STARTED WITH MULTIPATH TCP
35.1. UNDERSTANDING MPTCP
35.2. PREPARING RHEL TO ENABLE MPTCP SUPPORT
35.3. USING IPROUTE2 TO TEMPORARILY CONFIGURE AND ENABLE MULTIPLE PATHS FOR MPTCP
APPLICATIONS
35.4. PERMANENTLY CONFIGURING MULTIPLE PATHS FOR MPTCP APPLICATIONS
35.5. MONITORING MPTCP SUB-FLOWS
35.6. DISABLING MULTIPATH TCP IN THE KERNEL
CHAPTER 36. MANAGING THE MPTCPD SERVICE
36.1. CONFIGURING MPTCPD
36.2. MANAGING APPLICATIONS WITH MPTCPIZE TOOL
36.3. ENABLING MPTCP SOCKETS FOR A SERVICES USING THE MPTCPIZE UTILITY
CHAPTER 37. NETWORKMANAGER CONNECTION PROFILES IN KEYFILE FORMAT
37.1. THE KEYFILE FORMAT OF NETWORKMANAGER PROFILES
37.2. USING NMCLI TO CREATE KEYFILE CONNECTION PROFILES IN OFFLINE MODE
37.3. MANUALLY CREATING A NETWORKMANAGER PROFILE IN KEYFILE FORMAT
37.4. THE DIFFERENCES IN INTERFACE RENAMING WITH PROFILES IN IFCFG AND KEYFILE FORMAT
37.5. MIGRATING NETWORKMANAGER PROFILES FROM IFCFG TO KEYFILE FORMAT
CHAPTER 38. SYSTEMD NETWORK TARGETS AND SERVICES
38.1. DIFFERENCES BETWEEN THE NETWORK AND NETWORK-ONLINE SYSTEMD TARGET
38.2. OVERVIEW OF NETWORKMANAGER-WAIT-ONLINE
38.3. CONFIGURING A SYSTEMD SERVICE TO START AFTER THE NETWORK HAS BEEN STARTED
CHAPTER 39. INTRODUCTION TO NMSTATE
39.1. USING THE LIBNMSTATE LIBRARY IN A PYTHON APPLICATION
39.2. UPDATING THE CURRENT NETWORK CONFIGURATION USING NMSTATECTL
39.3. THE NMSTATE SYSTEMD SERVICE
39.4. NETWORK STATES FOR THE NETWORK RHEL SYSTEM ROLE
39.5. ADDITIONAL RESOURCES
CHAPTER 40. CAPTURING NETWORK PACKETS
40.1. USING XDPDUMP TO CAPTURE NETWORK PACKETS INCLUDING PACKETS DROPPED BY XDP
PROGRAMS
40.2. ADDITIONAL RESOURCES
CHAPTER 41. UNDERSTANDING THE EBPF NETWORKING FEATURES IN RHEL 9
41.1. OVERVIEW OF NETWORKING EBPF FEATURES IN RHEL 9
XDP
AF_XDP
Traffic Control
Socket filter
Control Groups
Stream Parser
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SO_REUSEPORT socket selection
Flow dissector
TCP Congestion Control
Routes with encapsulation
Socket lookup
41.2. OVERVIEW OF XDP FEATURES IN RHEL 9 BY NETWORK CARDS
CHAPTER 42. NETWORK TRACING USING THE BPF COMPILER COLLECTION
42.1. INSTALLING THE BCC-TOOLS PACKAGE
42.2. DISPLAYING TCP CONNECTIONS ADDED TO THE KERNEL’S ACCEPT QUEUE
42.3. TRACING OUTGOING TCP CONNECTION ATTEMPTS
42.4. MEASURING THE LATENCY OF OUTGOING TCP CONNECTIONS
42.5. DISPLAYING DETAILS ABOUT TCP PACKETS AND SEGMENTS THAT WERE DROPPED BY THE KERNEL
42.6. TRACING TCP SESSIONS
42.7. TRACING TCP RETRANSMISSIONS
42.8. DISPLAYING TCP STATE CHANGE INFORMATION
42.9. SUMMARIZING AND AGGREGATING TCP TRAFFIC SENT TO SPECIFIC SUBNETS
42.10. DISPLAYING THE NETWORK THROUGHPUT BY IP ADDRESS AND PORT
42.11. TRACING ESTABLISHED TCP CONNECTIONS
42.12. TRACING IPV4 AND IPV6 LISTEN ATTEMPTS
42.13. SUMMARIZING THE SERVICE TIME OF SOFT INTERRUPTS
42.14. SUMMARIZING PACKETS SIZE AND COUNT ON A NETWORK INTERFACE
42.15. ADDITIONAL RESOURCES
CHAPTER 43. CONFIGURING NETWORK DEVICES TO ACCEPT TRAFFIC FROM ALL MAC ADDRESSES
43.1. TEMPORARILY CONFIGURING A DEVICE TO ACCEPT ALL TRAFFIC
43.2. PERMANENTLY CONFIGURING A NETWORK DEVICE TO ACCEPT ALL TRAFFIC USING NMCLI
43.3. PERMANENTLY CONFIGURING A NETWORK DEVICE TO ACCEPT ALL TRAFFIC USING NMSTATECTL
CHAPTER 44. MIRRORING A NETWORK INTERFACE BY USING NMCLI
CHAPTER 45. USING NMSTATE-AUTOCONF TO AUTOMATICALLY CONFIGURE THE NETWORK STATE
USING LLDP
45.1. USING NMSTATE-AUTOCONF TO AUTOMATICALLY CONFIGURE NETWORK INTERFACES
CHAPTER 46. CONFIGURING 802.3 LINK SETTINGS
46.1. CONFIGURING 802.3 LINK SETTINGS USING THE NMCLI UTILITY
CHAPTER 47. GETTING STARTED WITH DPDK
47.1. INSTALLING THE DPDK PACKAGE
47.2. ADDITIONAL RESOURCES
CHAPTER 48. GETTING STARTED WITH TIPC
48.1. THE ARCHITECTURE OF TIPC
48.2. LOADING THE TIPC MODULE WHEN THE SYSTEM BOOTS
48.3. CREATING A TIPC NETWORK
48.4. ADDITIONAL RESOURCES
CHAPTER 49. AUTOMATICALLY CONFIGURING NETWORK INTERFACES IN PUBLIC CLOUDS USING NM-
CLOUD-SETUP
49.1. CONFIGURING AND PRE-DEPLOYING NM-CLOUD-SETUP
49.2. UNDERSTANDING THE ROLE OF IMDSV2 AND NM-CLOUD-SETUP IN THE RHEL EC2 INSTANCE
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Red Hat Enterprise Linux 9 Configuring and managing networking
8
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CHAPTER 1. IMPLEMENTING CONSISTENT NETWORK
INTERFACE NAMING
The udev device manager implements consistent device naming in Red Hat Enterprise Linux. The
device manager supports different naming schemes and, by default, assigns fixed names based on
firmware, topology, and location information.
Without consistent device naming, the Linux kernel assigns names to network interfaces by combining a
fixed prefix and an index. The index increases as the kernel initializes the network devices. For example,
eth0 represents the first Ethernet device being probed on start-up. If you add another network interface
controller to the system, the assignment of the kernel device names is no longer fixed because, after a
reboot, the devices can initialize in a different order. In that case, the kernel can name the devices
differently.
To solve this problem, udev assigns consistent device names. This has the following advantages:
Device names are stable across reboots.
Device names stay fixed even if you add or remove hardware.
Defective hardware can be seamlessly replaced.
The network naming is stateless and does not require explicit configuration files.
WARNING
Generally, Red Hat does not support systems where consistent device naming is
disabled. For exceptions, see the Is it safe to set net.ifnames=0 solution.
1.1. HOW THE UDEV DEVICE MANAGER RENAMES NETWORK
INTERFACES
To implement a consistent naming scheme for network interfaces, the udev device manager processes
the following rule files in the listed order:
1. Optional: /usr/lib/udev/rules.d/60-net.rules
This file exists only if you install the initscripts-rename-device package. The
/usr/lib/udev/rules.d/60-net.rules file defines that the deprecated
/usr/lib/udev/rename_device helper utility searches for the HWADDR parameter in
/etc/sysconfig/network-scripts/ifcfg-* files. If the value set in the variable matches the MAC
address of an interface, the helper utility renames the interface to the name set in the DEVICE
parameter of the ifcfg file.
If the system uses only NetworkManager connection profiles in keyfile format, udev skips this
step.
2. Only on Dell systems: /usr/lib/udev/rules.d/71-biosdevname.rules
This file exists only if the biosdevname package is installed, and the rules file defines that the
biosdevname utility renames the interface according to its naming policy, if it was not renamed
in the previous step.
Red Hat Enterprise Linux 9 Configuring and managing networking
10
NOTE
Install and use biosdevname only on Dell systems.
3. /usr/lib/udev/rules.d/75-net-description.rules
This file defines how udev examines the network interface and sets the properties in udev-
internal variables. These variables are then processed in the next step by the
/usr/lib/udev/rules.d/80-net-setup-link.rules file. Some of the properties can be undefined.
4. /usr/lib/udev/rules.d/80-net-setup-link.rules
This file calls the net_setup_link builtin of the udev service, and udev renames the interface
based on the order of the policies in the NamePolicy parameter in the
/usr/lib/systemd/network/99-default.link file. For further details, see Network interface
naming policies.
If none of the policies applies, udev does not rename the interface.
Additional resources
Why are systemd network interface names different between major RHEL versions solution
1.2. NETWORK INTERFACE NAMING POLICIES
By default, the udev device manager uses the /usr/lib/systemd/network/99-default.link file to
determine which device naming policies to apply when it renames interfaces. The NamePolicy
parameter in this file defines which policies udev uses and in which order:
NamePolicy=keep kernel database onboard slot path
The following table describes the different actions of udev based on which policy matches first as
specified by the NamePolicy parameter:
Policy Description Example name
keep If the device already has a name that was assigned in the user
space, udev does not rename this device. For example, this is
the case if the name was assigned during device creation or by a
rename operation.
kernel If the kernel indicates that a device name is predictable, udev
does not rename this device.
lo
database This policy assigns names based on mappings in the udev
hardware database. For details, see the hwdb(7) man page.
idrac
onboard Device names incorporate firmware or BIOS-provided index
numbers for onboard devices.
eno1
slot Device names incorporate firmware or BIOS-provided PCI
Express (PCIe) hot-plug slot-index numbers.
ens1
CHAPTER 1. IMPLEMENTING CONSISTENT NETWORK INTERFACE NAMING
11
path Device names incorporate the physical location of the connector
of the hardware.
enp1s0
mac Device names incorporate the MAC address. By default, Red Hat
Enterprise Linux does not use this policy, but administrators can
enable it.
enx525400d5e0f
b
Policy Description Example name
Additional resources
How the udev device manager renames network interfaces
systemd.link(5) man page
1.3. NETWORK INTERFACE NAMING SCHEMES
The udev device manager uses certain stable interface attributes that device drivers provide to
generate consistent device names.
If a new udev version changes how the service creates names for certain interfaces, Red Hat adds a new
scheme version and documents the details in the systemd.net-naming-scheme(7) man page. By
default, Red Hat Enterprise Linux (RHEL) 9 uses the rhel-9.0 naming scheme, even if you install or
update to a later minor version of RHEL.
To prevent new drivers from providing more or other attributes for a network interface, the rhel-net-
naming-sysattrs package provides the /usr/lib/udev/hwdb.d/50-net-naming-sysattr-allowlist.hwdb
database. This database defines which sysfs values the udev service can use to create network
interface names. The entries in the database are also versioned and influenced by the scheme version.
NOTE
On RHEL 9.4 and later, you can also use all rhel-8.* naming schemes.
If you want to use a scheme other than the default, you can switch the network interface naming
scheme.
For further details about the naming schemes for different device types and platforms, see the
systemd.net-naming-scheme(7) man page.
1.4. SWITCHING TO A DIFFERENT NETWORK INTERFACE NAMING
SCHEME
By default, Red Hat Enterprise Linux (RHEL) 9 uses the rhel-9.0 naming scheme, even if you install or
update to a later minor version of RHEL. While the default naming scheme fits in most scenarios, there
might be reasons to switch to a different scheme version, for example:
A new scheme can help to better identify a device if it adds additional attributes, such as a slot
number, to an interface name.
An new scheme can prevent udev from falling back to the kernel-assigned device names ( eth*).
Red Hat Enterprise Linux 9 Configuring and managing networking
12
An new scheme can prevent udev from falling back to the kernel-assigned device names ( eth*).
This happens if the driver does not provide enough unique attributes for two or more interfaces
to generate unique names for them.
Prerequisites
You have access to the console of the server.
Procedure
1. List the network interfaces:
# ip link show
2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
mode DEFAULT group default qlen 1000
link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
...
Record the MAC addresses of the interfaces.
2. Optional: Display the ID_NET_NAMING_SCHEME property of a network interface to identify
the naming scheme that RHEL currently uses:
# udevadm info --query=property --property=ID_NET_NAMING_SCHEME
/sys/class/net/eno1'
ID_NET_NAMING_SCHEME=rhel-9.0
Note that the property is not available on the lo loopback device.
3. Append the net.naming-scheme=<scheme> option to the command line of all installed
kernels, for example:
# grubby --update-kernel=ALL --args=net.naming-scheme=rhel-9.4
4. Reboot the system.
# reboot
5. Based on the MAC addresses you recorded, identify the new names of network interfaces that
have changed due to the different naming scheme:
# ip link show
2: eno1np0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state
UP mode DEFAULT group default qlen 1000
link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
...
After switching the scheme, udev names in this example the device with MAC address
00:00:5e:00:53:1a eno1np0, whereas it was named eno1 before.
6. Identify which NetworkManager connection profile uses an interface with the previous name:
# nmcli -f device,name connection show
DEVICE NAME
CHAPTER 1. IMPLEMENTING CONSISTENT NETWORK INTERFACE NAMING
13
eno1 example_profile
...
7. Set the connection.interface-name property in the connection profile to the new interface
name:
# nmcli connection modify example_profile connection.interface-name "eno1np0"
8. Reactivate the connection profile:
# nmcli connection up example_profile
Verification
Identify the naming scheme that RHEL now uses by displaying the ID_NET_NAMING_SCHEME
property of a network interface:
# udevadm info --query=property --property=ID_NET_NAMING_SCHEME
/sys/class/net/eno1np0'
ID_NET_NAMING_SCHEME=_rhel-9.4
Additional resources
Network interface naming schemes
1.5. CUSTOMIZING THE PREFIX FOR ETHERNET INTERFACES DURING
INSTALLATION
If you do not want to use the default device-naming policy for Ethernet interfaces, you can set a custom
device prefix during the Red Hat Enterprise Linux (RHEL) installation.
IMPORTANT
Red Hat supports systems with customized Ethernet prefixes only if you set the prefix
during the RHEL installation. Using the prefixdevname utility on already deployed
systems is not supported.
If you set a device prefix during the installation, the udev service uses the <prefix><index> format for
Ethernet interfaces after the installation. For example, if you set the prefix net, the service assigns the
names net0, net1, and so on to the Ethernet interfaces.
The udev service appends the index to the custom prefix, and preserves the index values of known
Ethernet interfaces. If you add an interface, udev assigns an index value that is one greater than the
previously-assigned index value to the new interface.
Prerequisites
The prefix consists of ASCII characters.
The prefix is an alphanumeric string.
The prefix is shorter than 16 characters.
Red Hat Enterprise Linux 9 Configuring and managing networking
14
The prefix does not conflict with any other well-known network interface prefix, such as eth,
eno, ens, and em.
Procedure
1. Boot the Red Hat Enterprise Linux installation media.
2. In the boot manager, follow these steps:
a. Select the Install Red Hat Enterprise Linux <version> entry.
b. Press Tab to edit the entry.
c. Append net.ifnames.prefix=<prefix> to the kernel options.
d. Press Enter to start the installation program.
3. Install Red Hat Enterprise Linux.
Verification
To verify the interface names, display the network interfaces:
# ip link show
...
2: net0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
mode DEFAULT group default qlen 1000
link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
...
Additional resources
Interactively installing RHEL from installation media
1.6. CONFIGURING USER-DEFINED NETWORK INTERFACE NAMES BY
USING UDEV RULES
You can use udev rules to implement custom network interface names that reflect your organization’s
requirements.
Procedure
1. Identify the network interface that you want to rename:
# ip link show
...
enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
mode DEFAULT group default qlen 1000
link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
...
Record the MAC address of the interface.
2. Display the device type ID of the interface:
CHAPTER 1. IMPLEMENTING CONSISTENT NETWORK INTERFACE NAMING
15
# cat /sys/class/net/enp1s0/type
1
3. Create the /etc/udev/rules.d/70-persistent-net.rules file, and add a rule for each interface that
you want to rename:
SUBSYSTEM=="net",ACTION=="add",ATTR{address}=="<MAC_address>",ATTR{type}=="<
device_type_id>",NAME="<new_interface_name>"
IMPORTANT
Use only 70-persistent-net.rules as a file name if you require consistent device
names during the boot process. The dracut utility adds a file with this name to
the initrd image if you regenerate the RAM disk image.
For example, use the following rule to rename the interface with MAC address
00:00:5e:00:53:1a to provider0:
SUBSYSTEM=="net",ACTION=="add",ATTR{address}=="00:00:5e:00:53:1a",ATTR{type}=="
1",NAME="provider0"
4. Optional: Regenerate the initrd RAM disk image:
# dracut -f
You require this step only if you need networking capabilities in the RAM disk. For example, this
is the case if the root file system is stored on a network device, such as iSCSI.
5. Identify which NetworkManager connection profile uses the interface that you want to rename:
# nmcli -f device,name connection show
DEVICE NAME
enp1s0 example_profile
...
6. Unset the connection.interface-name property in the connection profile:
# nmcli connection modify example_profile connection.interface-name ""
7. Temporarily, configure the connection profile to match both the new and the previous interface
name:
# nmcli connection modify example_profile match.interface-name "provider0 enp1s0"
8. Reboot the system:
# reboot
9. Verify that the device with the MAC address that you specified in the link file has been renamed
to provider0:
# ip link show
Red Hat Enterprise Linux 9 Configuring and managing networking
16
provider0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode
DEFAULT group default qlen 1000
link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
...
10. Configure the connection profile to match only the new interface name:
# nmcli connection modify example_profile match.interface-name "provider0"
You have now removed the old interface name from the connection profile.
11. Reactivate the connection profile:
# nmcli connection up example_profile
Additional resources
udev(7) man page
1.7. CONFIGURING USER-DEFINED NETWORK INTERFACE NAMES BY
USING SYSTEMD LINK FILES
You can use systemd link files to implement custom network interface names that reflect your
organization’s requirements.
Prerequisites
You must meet one of these conditions: NetworkManager does not manage this interface, or
the corresponding connection profile uses the keyfile format.
Procedure
1. Identify the network interface that you want to rename:
# ip link show
...
enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
mode DEFAULT group default qlen 1000
link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
...
Record the MAC address of the interface.
2. If it does not already exist, create the /etc/systemd/network/ directory:
# mkdir -p /etc/systemd/network/
3. For each interface that you want to rename, create a 70-*.link file in the /etc/systemd/network/
directory with the following content:
[Match]
MACAddress=<MAC_address>
CHAPTER 1. IMPLEMENTING CONSISTENT NETWORK INTERFACE NAMING
17
[Link]
Name=<new_interface_name>
IMPORTANT
Use a file name with a 70- prefix to keep the file names consistent with the udev
rules-based solution.
For example, create the /etc/systemd/network/70-provider0.link file with the following
content to rename the interface with MAC address 00:00:5e:00:53:1a to provider0:
[Match]
MACAddress=00:00:5e:00:53:1a
[Link]
Name=provider0
4. Optional: Regenerate the initrd RAM disk image:
# dracut -f
You require this step only if you need networking capabilities in the RAM disk. For example, this
is the case if the root file system is stored on a network device, such as iSCSI.
5. Identify which NetworkManager connection profile uses the interface that you want to rename:
# nmcli -f device,name connection show
DEVICE NAME
enp1s0 example_profile
...
6. Unset the connection.interface-name property in the connection profile:
# nmcli connection modify example_profile connection.interface-name ""
7. Temporarily, configure the connection profile to match both the new and the previous interface
name:
# nmcli connection modify example_profile match.interface-name "provider0 enp1s0"
8. Reboot the system:
# reboot
9. Verify that the device with the MAC address that you specified in the link file has been renamed
to provider0:
# ip link show
provider0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode
DEFAULT group default qlen 1000
link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
...
Red Hat Enterprise Linux 9 Configuring and managing networking
18
10. Configure the connection profile to match only the new interface name:
# nmcli connection modify example_profile match.interface-name "provider0"
You have now removed the old interface name from the connection profile.
11. Reactivate the connection profile.
# nmcli connection up example_profile
Additional resources
systemd.link(5) man page
1.8. ASSIGNING ALTERNATIVE NAMES TO A NETWORK INTERFACE BY
USING SYSTEMD LINK FILES
With alternative interface naming, the kernel can assign additional names to network interfaces. You can
use these alternative names in the same way as the normal interface names in commands that require a
network interface name.
Prerequisites
You must use ASCII characters for the alternative name.
The alternative name must be shorter than 128 characters.
Procedure
1. Display the network interface names and their MAC addresses:
# ip link show
...
enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
mode DEFAULT group default qlen 1000
link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
...
Record the MAC address of the interface to which you want to assign an alternative name.
2. If it does not already exist, create the /etc/systemd/network/ directory:
# mkdir -p /etc/systemd/network/
3. For each interface that must have an alternative name, create a *.link file in the
/etc/systemd/network/ directory with the following content:
[Match]
MACAddress=<MAC_address>
[Link]
CHAPTER 1. IMPLEMENTING CONSISTENT NETWORK INTERFACE NAMING
19
AlternativeName=<alternative_interface_name_1>
AlternativeName=<alternative_interface_name_2>
AlternativeName=<alternative_interface_name_n>
For example, create the /etc/systemd/network/70-altname.link file with the following content
to assign provider as an alternative name to the interface with MAC address
00:00:5e:00:53:1a:
[Match]
MACAddress=00:00:5e:00:53:1a
[Link]
AlternativeName=provider
4. Regenerate the initrd RAM disk image:
# dracut -f
5. Reboot the system:
# reboot
Verification
Use the alternative interface name. For example, display the IP address settings of the device
with the alternative name provider:
# ip address show provider
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
group default qlen 1000
link/ether 00:00:5e:00:53:1a brd ff:ff:ff:ff:ff:ff
altname provider
...
Additional resources
What is AlternativeNamesPolicy in Interface naming scheme?
Red Hat Enterprise Linux 9 Configuring and managing networking
20
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
NetworkManager creates a connection profile for each Ethernet adapter that is installed in a host. By
default, this profile uses DHCP for both IPv4 and IPv6 connections. Modify this automatically-created
profile or add a new one in the following cases:
The network requires custom settings, such as a static IP address configuration.
You require multiple profiles because the host roams among different networks.
Red Hat Enterprise Linux provides administrators different options to configure Ethernet connections.
For example:
Use nmcli to configure connections on the command line.
Use nmtui to configure connections in a text-based user interface.
Use the GNOME Settings menu or nm-connection-editor application to configure connections
in a graphical interface.
Use nmstatectl to configure connections through the Nmstate API.
Use RHEL system roles to automate the configuration of connections on one or multiple hosts.
NOTE
If you want to manually configure Ethernet connections on hosts running in the Microsoft
Azure cloud, disable the cloud-init service or configure it to ignore the network settings
retrieved from the cloud environment. Otherwise, cloud-init will override on the next
reboot the network settings that you have manually configured.
2.1. CONFIGURING AN ETHERNET CONNECTION BY USING NMCLI
If you connect a host to the network over Ethernet, you can manage the connection’s settings on the
command line by using the nmcli utility.
Prerequisites
A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s
configuration.
Procedure
1. List the NetworkManager connection profiles:
# nmcli connection show
NAME UUID TYPE DEVICE
Wired connection 1 a5eb6490-cc20-3668-81f8-0314a27f3f75 ethernet enp1s0
By default, NetworkManager creates a profile for each NIC in the host. If you plan to connect
this NIC only to a specific network, adapt the automatically-created profile. If you plan to
connect this NIC to networks with different settings, create individual profiles for each network.
2. If you want to create an additional connection profile, enter:
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
21
# nmcli connection add con-name <connection-name> ifname <device-name> type
ethernet
Skip this step to modify an existing profile.
3. Optional: Rename the connection profile:
# nmcli connection modify "Wired connection 1" connection.id "Internal-LAN"
On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a
profile.
4. Display the current settings of the connection profile:
# nmcli connection show Internal-LAN
...
connection.interface-name: enp1s0
connection.autoconnect: yes
ipv4.method: auto
ipv6.method: auto
...
5. Configure the IPv4 settings:
To use DHCP, enter:
# nmcli connection modify Internal-LAN ipv4.method auto
Skip this step if ipv4.method is already set to auto (default).
To set a static IPv4 address, network mask, default gateway, DNS servers, and search
domain, enter:
# nmcli connection modify Internal-LAN ipv4.method manual ipv4.addresses
192.0.2.1/24 ipv4.gateway 192.0.2.254 ipv4.dns 192.0.2.200 ipv4.dns-search
example.com
6. Configure the IPv6 settings:
To use stateless address autoconfiguration (SLAAC), enter:
# nmcli connection modify Internal-LAN ipv6.method auto
Skip this step if ipv6.method is already set to auto (default).
To set a static IPv6 address, network mask, default gateway, DNS servers, and search
domain, enter:
# nmcli connection modify Internal-LAN ipv6.method manual ipv6.addresses
2001:db8:1::fffe/64 ipv6.gateway 2001:db8:1::fffe ipv6.dns 2001:db8:1::ffbb
ipv6.dns-search example.com
7. To customize other settings in the profile, use the following command:
Red Hat Enterprise Linux 9 Configuring and managing networking
22
# nmcli connection modify <connection-name> <setting> <value>
Enclose values with spaces or semicolons in quotes.
8. Activate the profile:
# nmcli connection up Internal-LAN
Verification
1. Display the IP settings of the NIC:
# ip address show enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
group default qlen 1000
link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::fffe/64 scope global noprefixroute
valid_lft forever preferred_lft forever
2. Display the IPv4 default gateway:
# ip route show default
default via 192.0.2.254 dev enp1s0 proto static metric 102
3. Display the IPv6 default gateway:
# ip -6 route show default
default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
4. Display the DNS settings:
# cat /etc/resolv.conf
search example.com
nameserver 192.0.2.200
nameserver 2001:db8:1::ffbb
If multiple connection profiles are active at the same time, the order of nameserver entries
depend on the DNS priority values in these profile and the connection types.
5. Use the ping utility to verify that this host can send packets to other hosts:
# ping <host-name-or-IP-address>
Troubleshooting
Verify that the network cable is plugged-in to the host and a switch.
Check whether the link failure exists only on this host or also on other hosts connected to the
same switch.
Verify that the network cable and the network interface are working as expected. Perform
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
23
Verify that the network cable and the network interface are working as expected. Perform
hardware diagnosis steps and replace defect cables and network interface cards.
If the configuration on the disk does not match the configuration on the device, starting or
restarting NetworkManager creates an in-memory connection that reflects the configuration of
the device. For further details and how to avoid this problem, see the NetworkManager
duplicates a connection after restart of NetworkManager service solution.
Additional resources
nm-settings(5) man page
2.2. CONFIGURING AN ETHERNET CONNECTION BY USING THE NMCLI
INTERACTIVE EDITOR
If you connect a host to the network over Ethernet, you can manage the connection’s settings on the
command line by using the nmcli utility.
Prerequisites
A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s
configuration.
Procedure
1. List the NetworkManager connection profiles:
# nmcli connection show
NAME UUID TYPE DEVICE
Wired connection 1 a5eb6490-cc20-3668-81f8-0314a27f3f75 ethernet enp1s0
By default, NetworkManager creates a profile for each NIC in the host. If you plan to connect
this NIC only to a specific network, adapt the automatically-created profile. If you plan to
connect this NIC to networks with different settings, create individual profiles for each network.
2. Start nmcli in interactive mode:
To create an additional connection profile, enter:
# nmcli connection edit type ethernet con-name "<connection-name>"
To modify an existing connection profile, enter:
# nmcli connection edit con-name "<connection-name>"
3. Optional: Rename the connection profile:
nmcli> set connection.id Internal-LAN
On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a
profile.
Do not use quotes to set an ID that contains spaces to avoid that nmcli makes the quotes part
Red Hat Enterprise Linux 9 Configuring and managing networking
24
Do not use quotes to set an ID that contains spaces to avoid that nmcli makes the quotes part
of the name. For example, to set Example Connection as ID, enter set connection.id Example
Connection.
4. Display the current settings of the connection profile:
nmcli> print
...
connection.interface-name: enp1s0
connection.autoconnect: yes
ipv4.method: auto
ipv6.method: auto
...
5. If you create a new connection profile, set the network interface:
nmcli> set connection.interface-name enp1s0
6. Configure the IPv4 settings:
To use DHCP, enter:
nmcli> set ipv4.method auto
Skip this step if ipv4.method is already set to auto (default).
To set a static IPv4 address, network mask, default gateway, DNS servers, and search
domain, enter:
nmcli> ipv4.addresses 192.0.2.1/24
Do you also want to set 'ipv4.method' to 'manual'? [yes]: yes
nmcli> ipv4.gateway 192.0.2.254
nmcli> ipv4.dns 192.0.2.200
nmcli> ipv4.dns-search example.com
7. Configure the IPv6 settings:
To use stateless address autoconfiguration (SLAAC), enter:
nmcli> set ipv6.method auto
Skip this step if ipv6.method is already set to auto (default).
To set a static IPv6 address, network mask, default gateway, DNS servers, and search
domain, enter:
nmcli> ipv6.addresses 2001:db8:1::fffe/64
Do you also want to set 'ipv6.method' to 'manual'? [yes]: yes
nmcli> ipv6.gateway 2001:db8:1::fffe
nmcli> ipv6.dns 2001:db8:1::ffbb
nmcli> ipv6.dns-search example.com
8. Save and activate the connection:
nmcli> save persistent
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
25
9. Leave the interactive mode:
nmcli> quit
Verification
1. Display the IP settings of the NIC:
# ip address show enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
group default qlen 1000
link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::fffe/64 scope global noprefixroute
valid_lft forever preferred_lft forever
2. Display the IPv4 default gateway:
# ip route show default
default via 192.0.2.254 dev enp1s0 proto static metric 102
3. Display the IPv6 default gateway:
# ip -6 route show default
default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
4. Display the DNS settings:
# cat /etc/resolv.conf
search example.com
nameserver 192.0.2.200
nameserver 2001:db8:1::ffbb
If multiple connection profiles are active at the same time, the order of nameserver entries
depend on the DNS priority values in these profile and the connection types.
5. Use the ping utility to verify that this host can send packets to other hosts:
# ping <host-name-or-IP-address>
Troubleshooting
Verify that the network cable is plugged-in to the host and a switch.
Check whether the link failure exists only on this host or also on other hosts connected to the
same switch.
Verify that the network cable and the network interface are working as expected. Perform
hardware diagnosis steps and replace defect cables and network interface cards.
If the configuration on the disk does not match the configuration on the device, starting or
Red Hat Enterprise Linux 9 Configuring and managing networking
26
restarting NetworkManager creates an in-memory connection that reflects the configuration of
the device. For further details and how to avoid this problem, see the NetworkManager
duplicates a connection after restart of NetworkManager service solution
Additional resources
nm-settings(5) man page
nmcli(1) man page
2.3. CONFIGURING AN ETHERNET CONNECTION BY USING NMTUI
If you connect a host to the network over Ethernet, you can manage the connection’s settings in a text-
based user interface by using the nmtui application. Use nmtui to create new profiles and to update
existing ones on a host without a graphical interface.
NOTE
In nmtui:
Navigate by using the cursor keys.
Press a button by selecting it and hitting Enter.
Select and clear checkboxes by using Space.
Prerequisites
A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s
configuration.
Procedure
1. If you do not know the network device name you want to use in the connection, display the
available devices:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp1s0 ethernet unavailable --
...
2. Start nmtui:
# nmtui
3. Select Edit a connection, and press Enter.
4. Choose whether to add a new connection profile or to modify an existing one:
To create a new profile:
i. Press Add.
ii. Select Ethernet from the list of network types, and press Enter.
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
27
To modify an existing profile, select the profile from the list, and press Enter.
5. Optional: Update the name of the connection profile.
On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a
profile.
6. If you create a new connection profile, enter the network device name into the Device field.
7. Depending on your environment, configure the IP address settings in the IPv4 configuration
and IPv6 configuration areas accordingly. For this, press the button next to these areas, and
select:
Disabled, if this connection does not require an IP address.
Automatic, if a DHCP server dynamically assigns an IP address to this NIC.
Manual, if the network requires static IP address settings. In this case, you must fill further
fields:
i. Press Show next to the protocol you want to configure to display additional fields.
ii. Press Add next to Addresses, and enter the IP address and the subnet mask in
Classless Inter-Domain Routing (CIDR) format.
If you do not specify a subnet mask, NetworkManager sets a /32 subnet mask for IPv4
addresses and /64 for IPv6 addresses.
iii. Enter the address of the default gateway.
iv. Press Add next to DNS servers, and enter the DNS server address.
v. Press Add next to Search domains, and enter the DNS search domain.
Figure 2.1. Example of an Ethernet connection with static IP address settings
Red Hat Enterprise Linux 9 Configuring and managing networking
28
Figure 2.1. Example of an Ethernet connection with static IP address settings
8. Press OK to create and automatically activate the new connection.
9. Press Back to return to the main menu.
10. Select Quit, and press Enter to close the nmtui application.
Verification
1. Display the IP settings of the NIC:
# ip address show enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
group default qlen 1000
link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
29
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::fffe/64 scope global noprefixroute
valid_lft forever preferred_lft forever
2. Display the IPv4 default gateway:
# ip route show default
default via 192.0.2.254 dev enp1s0 proto static metric 102
3. Display the IPv6 default gateway:
# ip -6 route show default
default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
4. Display the DNS settings:
# cat /etc/resolv.conf
search example.com
nameserver 192.0.2.200
nameserver 2001:db8:1::ffbb
If multiple connection profiles are active at the same time, the order of nameserver entries
depend on the DNS priority values in these profile and the connection types.
5. Use the ping utility to verify that this host can send packets to other hosts:
# ping <host-name-or-IP-address>
Troubleshooting
Verify that the network cable is plugged-in to the host and a switch.
Check whether the link failure exists only on this host or also on other hosts connected to the
same switch.
Verify that the network cable and the network interface are working as expected. Perform
hardware diagnosis steps and replace defect cables and network interface cards.
If the configuration on the disk does not match the configuration on the device, starting or
restarting NetworkManager creates an in-memory connection that reflects the configuration of
the device. For further details and how to avoid this problem, see the NetworkManager
duplicates a connection after restart of NetworkManager service solution.
Additional resources
Configuring NetworkManager to avoid using a specific profile to provide a default gateway
Configuring the order of DNS servers
2.4. CONFIGURING AN ETHERNET CONNECTION BY USING
CONTROL-CENTER
If you connect a host to the network over Ethernet, you can manage the connection’s settings with a
Red Hat Enterprise Linux 9 Configuring and managing networking
30
If you connect a host to the network over Ethernet, you can manage the connection’s settings with a
graphical interface by using the GNOME Settings menu.
Note that control-center does not support as many configuration options as the nm-connection-editor
application or the nmcli utility.
Prerequisites
A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s
configuration.
GNOME is installed.
Procedure
1. Press the Super key, enter Settings, and press Enter.
2. Select Network in the navigation on the left.
3. Choose whether to add a new connection profile or to modify an existing one:
To create a new profile, click the + button next to the Ethernet entry.
To modify an existing profile, click the gear icon next to the profile entry.
4. Optional: On the Identity tab, update the name of the connection profile.
On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a
profile.
5. Depending on your environment, configure the IP address settings on the IPv4 and IPv6 tabs
accordingly:
To use DHCP or IPv6 stateless address autoconfiguration (SLAAC), select Automatic
(DHCP) as method (default).
To set a static IP address, network mask, default gateway, DNS servers, and search domain,
select Manual as method, and fill the fields on the tabs:
6. Depending on whether you add or modify a connection profile, click the Add or Apply button to
save the connection.
The GNOME control-center automatically activates the connection.
Verification
1. Display the IP settings of the NIC:
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
31
# ip address show enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
group default qlen 1000
link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::fffe/64 scope global noprefixroute
valid_lft forever preferred_lft forever
2. Display the IPv4 default gateway:
# ip route show default
default via 192.0.2.254 dev enp1s0 proto static metric 102
3. Display the IPv6 default gateway:
# ip -6 route show default
default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
4. Display the DNS settings:
# cat /etc/resolv.conf
search example.com
nameserver 192.0.2.200
nameserver 2001:db8:1::ffbb
If multiple connection profiles are active at the same time, the order of nameserver entries
depend on the DNS priority values in these profile and the connection types.
5. Use the ping utility to verify that this host can send packets to other hosts:
# ping <host-name-or-IP-address>
Troubleshooting steps
Verify that the network cable is plugged-in to the host and a switch.
Check whether the link failure exists only on this host or also on other hosts connected to the
same switch.
Verify that the network cable and the network interface are working as expected. Perform
hardware diagnosis steps and replace defect cables and network interface cards.
If the configuration on the disk does not match the configuration on the device, starting or
restarting NetworkManager creates an in-memory connection that reflects the configuration of
the device. For further details and how to avoid this problem, see the NetworkManager
duplicates a connection after restart of NetworkManager service solution.
2.5. CONFIGURING AN ETHERNET CONNECTION BY USING NM-
CONNECTION-EDITOR
If you connect a host to the network over Ethernet, you can manage the connection’s settings with a
graphical interface by using the nm-connection-editor application.
Red Hat Enterprise Linux 9 Configuring and managing networking
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Prerequisites
A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s
configuration.
GNOME is installed.
Procedure
1. Open a terminal, and enter:
$ nm-connection-editor
2. Choose whether to add a new connection profile or to modify an existing one:
To create a new profile:
i. Click the + button
ii. Select Ethernet as connection type, and click Create.
To modify an existing profile, double-click the profile entry.
3. Optional: Update the name of the profile in the Connection Name field.
On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a
profile.
4. If you create a new profile, select the device on the Ethernet tab:
5. Depending on your environment, configure the IP address settings on the IPv4 Settings and
IPv6 Settings tabs accordingly:
To use DHCP or IPv6 stateless address autoconfiguration (SLAAC), select Automatic
(DHCP) as method (default).
To set a static IP address, network mask, default gateway, DNS servers, and search domain,
select Manual as method, and fill the fields on the tabs:
6. Click Save.
7. Close nm-connection-editor.
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
33
Verification
1. Display the IP settings of the NIC:
# ip address show enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
group default qlen 1000
link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::fffe/64 scope global noprefixroute
valid_lft forever preferred_lft forever
2. Display the IPv4 default gateway:
# ip route show default
default via 192.0.2.254 dev enp1s0 proto static metric 102
3. Display the IPv6 default gateway:
# ip -6 route show default
default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
4. Display the DNS settings:
# cat /etc/resolv.conf
search example.com
nameserver 192.0.2.200
nameserver 2001:db8:1::ffbb
If multiple connection profiles are active at the same time, the order of nameserver entries
depend on the DNS priority values in these profile and the connection types.
5. Use the ping utility to verify that this host can send packets to other hosts:
# ping <host-name-or-IP-address>
Troubleshooting steps
Verify that the network cable is plugged-in to the host and a switch.
Check whether the link failure exists only on this host or also on other hosts connected to the
same switch.
Verify that the network cable and the network interface are working as expected. Perform
hardware diagnosis steps and replace defect cables and network interface cards.
If the configuration on the disk does not match the configuration on the device, starting or
restarting NetworkManager creates an in-memory connection that reflects the configuration of
the device. For further details and how to avoid this problem, see the NetworkManager
duplicates a connection after restart of NetworkManager service solution.
Additional Resources
Red Hat Enterprise Linux 9 Configuring and managing networking
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Configuring NetworkManager to avoid using a specific profile to provide a default gateway
Configuring the order of DNS servers
2.6. CONFIGURING AN ETHERNET CONNECTION WITH A STATIC IP
ADDRESS BY USING NMSTATECTL
Use the nmstatectl utility to configure an Ethernet connection through the Nmstate API. The Nmstate
API ensures that, after setting the configuration, the result matches the configuration file. If anything
fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.
Prerequisites
A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s
configuration.
The nmstate package is installed.
Procedure
1. Create a YAML file, for example ~/create-ethernet-profile.yml, with the following content:
---
interfaces:
- name: enp1s0
type: ethernet
state: up
ipv4:
enabled: true
address:
- ip: 192.0.2.1
prefix-length: 24
dhcp: false
ipv6:
enabled: true
address:
- ip: 2001:db8:1::1
prefix-length: 64
autoconf: false
dhcp: false
routes:
config:
- destination: 0.0.0.0/0
next-hop-address: 192.0.2.254
next-hop-interface: enp1s0
- destination: ::/0
next-hop-address: 2001:db8:1::fffe
next-hop-interface: enp1s0
dns-resolver:
config:
search:
- example.com
server:
- 192.0.2.200
- 2001:db8:1::ffbb
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
35
These settings define an Ethernet connection profile for the enp1s0 device with the following
settings:
A static IPv4 address - 192.0.2.1 with the /24 subnet mask
A static IPv6 address - 2001:db8:1::1 with the /64 subnet mask
An IPv4 default gateway - 192.0.2.254
An IPv6 default gateway - 2001:db8:1::fffe
An IPv4 DNS server - 192.0.2.200
An IPv6 DNS server - 2001:db8:1::ffbb
A DNS search domain - example.com
2. Optional: You can define the identifier: mac-address and mac-address: <mac_address>
properties in the interfaces property to identify the network interface card by its MAC address
instead of its name, for example:
3. Apply the settings to the system:
# nmstatectl apply ~/create-ethernet-profile.yml
Verification
1. Display the current state in YAML format:
# nmstatectl show enp1s0
2. Display the IP settings of the NIC:
# ip address show enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
group default qlen 1000
link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::fffe/64 scope global noprefixroute
valid_lft forever preferred_lft forever
3. Display the IPv4 default gateway:
# ip route show default
default via 192.0.2.254 dev enp1s0 proto static metric 102
---
interfaces:
- name: <profile_name>
type: ethernet
identifier: mac-address
mac-address: <mac_address>
...
Red Hat Enterprise Linux 9 Configuring and managing networking
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4. Display the IPv6 default gateway:
# ip -6 route show default
default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
5. Display the DNS settings:
# cat /etc/resolv.conf
search example.com
nameserver 192.0.2.200
nameserver 2001:db8:1::ffbb
If multiple connection profiles are active at the same time, the order of nameserver entries
depend on the DNS priority values in these profile and the connection types.
6. Use the ping utility to verify that this host can send packets to other hosts:
# ping <host-name-or-IP-address>
Additional resources
nmstatectl(8) man page
/usr/share/doc/nmstate/examples/ directory
2.7. CONFIGURING AN ETHERNET CONNECTION WITH A STATIC IP
ADDRESS BY USING THE NETWORK RHEL SYSTEM ROLE WITH AN
INTERFACE NAME
To connect a Red Hat Enterprise Linux host to an Ethernet network, create a NetworkManager
connection profile for the network device. By using Ansible and the network RHEL system role, you can
automate this process and remotely configure connection profiles on the hosts defined in a playbook.
You can use the network RHEL system role to configure an Ethernet connection with static IP
addresses, gateways, and DNS settings, and assign them to a specified interface name.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
A physical or virtual Ethernet device exists in the server’s configuration.
The managed nodes use NetworkManager to configure the network.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
37
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
Query the Ansible facts of the managed node and verify the active network settings:
# ansible managed-node-01.example.com -m ansible.builtin.setup
...
"ansible_default_ipv4": {
"address": "192.0.2.1",
"alias": "enp1s0",
"broadcast": "192.0.2.255",
"gateway": "192.0.2.254",
"interface": "enp1s0",
"macaddress": "52:54:00:17:b8:b6",
"mtu": 1500,
"netmask": "255.255.255.0",
---
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: Ethernet connection profile with static IP address settings
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
- name: enp1s0
interface_name: enp1s0
type: ethernet
autoconnect: yes
ip:
address:
- 192.0.2.1/24
- 2001:db8:1::1/64
gateway4: 192.0.2.254
gateway6: 2001:db8:1::fffe
dns:
- 192.0.2.200
- 2001:db8:1::ffbb
dns_search:
- example.com
state: up
Red Hat Enterprise Linux 9 Configuring and managing networking
38
"network": "192.0.2.0",
"prefix": "24",
"type": "ether"
},
"ansible_default_ipv6": {
"address": "2001:db8:1::1",
"gateway": "2001:db8:1::fffe",
"interface": "enp1s0",
"macaddress": "52:54:00:17:b8:b6",
"mtu": 1500,
"prefix": "64",
"scope": "global",
"type": "ether"
},
...
"ansible_dns": {
"nameservers": [
"192.0.2.1",
"2001:db8:1::ffbb"
],
"search": [
"example.com"
]
},
...
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
2.8. CONFIGURING AN ETHERNET CONNECTION WITH A STATIC IP
ADDRESS BY USING THE NETWORK RHEL SYSTEM ROLE WITH A DEVICE
PATH
To connect a Red Hat Enterprise Linux host to an Ethernet network, create a NetworkManager
connection profile for the network device. By using Ansible and the network RHEL system role, you can
automate this process and remotely configure connection profiles on the hosts defined in a playbook.
You can use the network RHEL system role to configure an Ethernet connection with static IP
addresses, gateways, and DNS settings, and assign them to a device based on its path instead of its
name.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
A physical or virtual Ethernet device exists in the server’s configuration.
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
39
The managed nodes use NetworkManager to configure the network.
You know the path of the device. You can display the device path by using the udevadm info
/sys/class/net/<device_name> | grep ID_PATH= command.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
The settings specified in the example playbook include the following:
match
Defines that a condition must be met in order to apply the settings. You can only use this
variable with the path option.
path
Defines the persistent path of a device. You can set it as a fixed path or an expression. Its
value can contain modifiers and wildcards. The example applies the settings to devices that
match PCI ID 0000:00:0[1-3].0, but not 0000:00:02.0.
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
---
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: Ethernet connection profile with static IP address settings
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
- name: example
match:
path:
- pci-0000:00:0[1-3].0
- &!pci-0000:00:02.0
type: ethernet
autoconnect: yes
ip:
address:
- 192.0.2.1/24
- 2001:db8:1::1/64
gateway4: 192.0.2.254
gateway6: 2001:db8:1::fffe
dns:
- 192.0.2.200
- 2001:db8:1::ffbb
dns_search:
- example.com
state: up
Red Hat Enterprise Linux 9 Configuring and managing networking
40
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
Query the Ansible facts of the managed node and verify the active network settings:
# ansible managed-node-01.example.com -m ansible.builtin.setup
...
"ansible_default_ipv4": {
"address": "192.0.2.1",
"alias": "enp1s0",
"broadcast": "192.0.2.255",
"gateway": "192.0.2.254",
"interface": "enp1s0",
"macaddress": "52:54:00:17:b8:b6",
"mtu": 1500,
"netmask": "255.255.255.0",
"network": "192.0.2.0",
"prefix": "24",
"type": "ether"
},
"ansible_default_ipv6": {
"address": "2001:db8:1::1",
"gateway": "2001:db8:1::fffe",
"interface": "enp1s0",
"macaddress": "52:54:00:17:b8:b6",
"mtu": 1500,
"prefix": "64",
"scope": "global",
"type": "ether"
},
...
"ansible_dns": {
"nameservers": [
"192.0.2.1",
"2001:db8:1::ffbb"
],
"search": [
"example.com"
]
},
...
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
2.9. CONFIGURING AN ETHERNET CONNECTION WITH A DYNAMIC IP
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
41
2.9. CONFIGURING AN ETHERNET CONNECTION WITH A DYNAMIC IP
ADDRESS BY USING NMSTATECTL
Use the nmstatectl utility to configure an Ethernet connection through the Nmstate API. The Nmstate
API ensures that, after setting the configuration, the result matches the configuration file. If anything
fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.
Prerequisites
A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server’s
configuration.
A DHCP server is available in the network.
The nmstate package is installed.
Procedure
1. Create a YAML file, for example ~/create-ethernet-profile.yml, with the following content:
These settings define an Ethernet connection profile for the enp1s0 device. The connection
retrieves IPv4 addresses, IPv6 addresses, default gateway, routes, DNS servers, and search
domains from a DHCP server and IPv6 stateless address autoconfiguration (SLAAC).
2. Optional: You can define the identifier: mac-address and mac-address: <mac_address>
properties in the interfaces property to identify the network interface card by its MAC address
instead of its name, for example:
---
interfaces:
- name: enp1s0
type: ethernet
state: up
ipv4:
enabled: true
auto-dns: true
auto-gateway: true
auto-routes: true
dhcp: true
ipv6:
enabled: true
auto-dns: true
auto-gateway: true
auto-routes: true
autoconf: true
dhcp: true
---
interfaces:
- name: <profile_name>
type: ethernet
identifier: mac-address
mac-address: <mac_address>
...
Red Hat Enterprise Linux 9 Configuring and managing networking
42
3. Apply the settings to the system:
# nmstatectl apply ~/create-ethernet-profile.yml
Verification
1. Display the current state in YAML format:
# nmstatectl show enp1s0
2. Display the IP settings of the NIC:
# ip address show enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
group default qlen 1000
link/ether 52:54:00:17:b8:b6 brd ff:ff:ff:ff:ff:ff
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::fffe/64 scope global noprefixroute
valid_lft forever preferred_lft forever
3. Display the IPv4 default gateway:
# ip route show default
default via 192.0.2.254 dev enp1s0 proto static metric 102
4. Display the IPv6 default gateway:
# ip -6 route show default
default via 2001:db8:1::ffee dev enp1s0 proto static metric 102 pref medium
5. Display the DNS settings:
# cat /etc/resolv.conf
search example.com
nameserver 192.0.2.200
nameserver 2001:db8:1::ffbb
If multiple connection profiles are active at the same time, the order of nameserver entries
depend on the DNS priority values in these profile and the connection types.
6. Use the ping utility to verify that this host can send packets to other hosts:
# ping <host-name-or-IP-address>
Additional resources
nmstatectl(8) man page
/usr/share/doc/nmstate/examples/ directory
2.10. CONFIGURING AN ETHERNET CONNECTION WITH A DYNAMIC IP
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
43
2.10. CONFIGURING AN ETHERNET CONNECTION WITH A DYNAMIC IP
ADDRESS BY USING THE NETWORK RHEL SYSTEM ROLE WITH AN
INTERFACE NAME
To connect a Red Hat Enterprise Linux host to an Ethernet network, create a NetworkManager
connection profile for the network device. By using Ansible and the network RHEL system role, you can
automate this process and remotely configure connection profiles on the hosts defined in a playbook.
You can use the network RHEL system role to configure an Ethernet connection that retrieves its IP
addresses, gateways, and DNS settings from a DHCP server and IPv6 stateless address
autoconfiguration (SLAAC). With this role you can assign the connection profile to the specified
interface name.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
A physical or virtual Ethernet device exists in the server’s configuration.
A DHCP server and SLAAC are available in the network.
The managed nodes use the NetworkManager service to configure the network.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
The settings specified in the example playbook include the following:
dhcp4: yes
Enables automatic IPv4 address assignment from DHCP, PPP, or similar services.
auto6: yes
---
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: Ethernet connection profile with dynamic IP address settings
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
- name: enp1s0
interface_name: enp1s0
type: ethernet
autoconnect: yes
ip:
dhcp4: yes
auto6: yes
state: up
Red Hat Enterprise Linux 9 Configuring and managing networking
44
Enables IPv6 auto-configuration. By default, NetworkManager uses Router Advertisements.
If the router announces the managed flag, NetworkManager requests an IPv6 address and
prefix from a DHCPv6 server.
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
Query the Ansible facts of the managed node and verify that the interface received IP
addresses and DNS settings:
# ansible managed-node-01.example.com -m ansible.builtin.setup
...
"ansible_default_ipv4": {
"address": "192.0.2.1",
"alias": "enp1s0",
"broadcast": "192.0.2.255",
"gateway": "192.0.2.254",
"interface": "enp1s0",
"macaddress": "52:54:00:17:b8:b6",
"mtu": 1500,
"netmask": "255.255.255.0",
"network": "192.0.2.0",
"prefix": "24",
"type": "ether"
},
"ansible_default_ipv6": {
"address": "2001:db8:1::1",
"gateway": "2001:db8:1::fffe",
"interface": "enp1s0",
"macaddress": "52:54:00:17:b8:b6",
"mtu": 1500,
"prefix": "64",
"scope": "global",
"type": "ether"
},
...
"ansible_dns": {
"nameservers": [
"192.0.2.1",
"2001:db8:1::ffbb"
],
"search": [
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
45
"example.com"
]
},
...
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
2.11. CONFIGURING AN ETHERNET CONNECTION WITH A DYNAMIC IP
ADDRESS BY USING THE NETWORK RHEL SYSTEM ROLE WITH A DEVICE
PATH
To connect a Red Hat Enterprise Linux host to an Ethernet network, create a NetworkManager
connection profile for the network device. By using Ansible and the network RHEL system role, you can
automate this process and remotely configure connection profiles on the hosts defined in a playbook.
You can use the network RHEL system role to configure an Ethernet connection that retrieves its IP
addresses, gateways, and DNS settings from a DHCP server and IPv6 stateless address
autoconfiguration (SLAAC). The role can assign the connection profile to a device based on its path
instead of an interface name.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
A physical or virtual Ethernet device exists in the server’s configuration.
A DHCP server and SLAAC are available in the network.
The managed hosts use NetworkManager to configure the network.
You know the path of the device. You can display the device path by using the udevadm info
/sys/class/net/<device_name> | grep ID_PATH= command.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
---
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: Ethernet connection profile with dynamic IP address settings
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
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The settings specified in the example playbook include the following:
match: path
Defines that a condition must be met in order to apply the settings. You can only use this
variable with the path option.
path: <path_and_expressions>
Defines the persistent path of a device. You can set it as a fixed path or an expression. Its
value can contain modifiers and wildcards. The example applies the settings to devices that
match PCI ID 0000:00:0[1-3].0, but not 0000:00:02.0.
dhcp4: yes
Enables automatic IPv4 address assignment from DHCP, PPP, or similar services.
auto6: yes
Enables IPv6 auto-configuration. By default, NetworkManager uses Router Advertisements.
If the router announces the managed flag, NetworkManager requests an IPv6 address and
prefix from a DHCPv6 server.
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
Query the Ansible facts of the managed node and verify that the interface received IP
addresses and DNS settings:
# ansible managed-node-01.example.com -m ansible.builtin.setup
...
"ansible_default_ipv4": {
"address": "192.0.2.1",
"alias": "enp1s0",
"broadcast": "192.0.2.255",
- name: example
match:
path:
- pci-0000:00:0[1-3].0
- &!pci-0000:00:02.0
type: ethernet
autoconnect: yes
ip:
dhcp4: yes
auto6: yes
state: up
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
47
"gateway": "192.0.2.254",
"interface": "enp1s0",
"macaddress": "52:54:00:17:b8:b6",
"mtu": 1500,
"netmask": "255.255.255.0",
"network": "192.0.2.0",
"prefix": "24",
"type": "ether"
},
"ansible_default_ipv6": {
"address": "2001:db8:1::1",
"gateway": "2001:db8:1::fffe",
"interface": "enp1s0",
"macaddress": "52:54:00:17:b8:b6",
"mtu": 1500,
"prefix": "64",
"scope": "global",
"type": "ether"
},
...
"ansible_dns": {
"nameservers": [
"192.0.2.1",
"2001:db8:1::ffbb"
],
"search": [
"example.com"
]
},
...
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
2.12. CONFIGURING MULTIPLE ETHERNET INTERFACES BY USING A
SINGLE CONNECTION PROFILE BY INTERFACE NAME
In most cases, one connection profile contains the settings of one network device. However,
NetworkManager also supports wildcards when you set the interface name in connection profiles. If a
host roams between Ethernet networks with dynamic IP address assignment, you can use this feature to
create a single connection profile that you can use for multiple Ethernet interfaces.
Prerequisites
Multiple physical or virtual Ethernet devices exist in the server’s configuration.
A DHCP server is available in the network.
No connection profile exists on the host.
Procedure
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1. Add a connection profile that applies to all interface names starting with enp:
# nmcli connection add con-name "Wired connection 1" connection.multi-connect
multiple match.interface-name enp* type ethernet
Verification
1. Display all settings of the single connection profile:
# nmcli connection show "Wired connection 1"
connection.id: Wired connection 1
...
connection.multi-connect: 3 (multiple)
match.interface-name: enp*
...
3 indicates the number of interfaces active on the connection profile at the same time, and not
the number of network interfaces in the connection profile. The connection profile uses all
devices that match the pattern in the match.interface-name parameter and, therefore, the
connection profiles have the same Universally Unique Identifier (UUID).
2. Display the status of the connections:
# nmcli connection show
NAME UUID TYPE DEVICE
...
Wired connection 1 6f22402e-c0cc-49cf-b702-eaf0cd5ea7d1 ethernet enp7s0
Wired connection 1 6f22402e-c0cc-49cf-b702-eaf0cd5ea7d1 ethernet enp8s0
Wired connection 1 6f22402e-c0cc-49cf-b702-eaf0cd5ea7d1 ethernet enp9s0
Additional resources
nmcli(1) man page
nm-settings(5) man page
2.13. CONFIGURING A SINGLE CONNECTION PROFILE FOR MULTIPLE
ETHERNET INTERFACES USING PCI IDS
The PCI ID is a unique identifier of the devices connected to the system. The connection profile adds
multiple devices by matching interfaces based on a list of PCI IDs. You can use this procedure to
connect multiple device PCI IDs to the single connection profile.
Prerequisites
Multiple physical or virtual Ethernet devices exist in the server’s configuration.
A DHCP server is available in the network.
No connection profile exists on the host.
Procedure
1. Identify the device path. For example, to display the device paths of all interfaces starting with
CHAPTER 2. CONFIGURING AN ETHERNET CONNECTION
49
1. Identify the device path. For example, to display the device paths of all interfaces starting with
enp, enter :
# udevadm info /sys/class/net/enp | grep ID_PATH=*
...
E: ID_PATH=pci-0000:07:00.0
E: ID_PATH=pci-0000:08:00.0
2. Add a connection profile that applies to all PCI IDs matching the 0000:00:0[7-8].0 expression:
# nmcli connection add type ethernet connection.multi-connect multiple match.path
"pci-0000:07:00.0 pci-0000:08:00.0" con-name "Wired connection 1"
Verification
1. Display the status of the connection:
# nmcli connection show
NAME UUID TYPE DEVICE
Wired connection 1 9cee0958-512f-4203-9d3d-b57af1d88466 ethernet enp7s0
Wired connection 1 9cee0958-512f-4203-9d3d-b57af1d88466 ethernet enp8s0
...
2. To display all settings of the connection profile:
# nmcli connection show "Wired connection 1"
connection.id: Wired connection 1
...
connection.multi-connect: 3 (multiple)
match.path: pci-0000:07:00.0,pci-0000:08:00.0
...
This connection profile uses all devices with a PCI ID which match the pattern in the match.path
parameter and, therefore, the connection profiles have the same Universally Unique Identifier
(UUID).
Additional resources
nmcli(1) man page
nm-settings(5) man page
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CHAPTER 3. CONFIGURING A NETWORK BOND
A network bond is a method to combine or aggregate physical and virtual network interfaces to provide
a logical interface with higher throughput or redundancy. In a bond, the kernel handles all operations
exclusively. You can create bonds on different types of devices, such as Ethernet devices or VLANs.
Red Hat Enterprise Linux provides administrators different options to configure team devices. For
example:
Use nmcli to configure bond connections using the command line.
Use the RHEL web console to configure bond connections using a web browser.
Use nmtui to configure bond connections in a text-based user interface.
Use the nm-connection-editor application to configure bond connections in a graphical
interface.
Use nmstatectl to configure bond connections through the Nmstate API.
Use RHEL system roles to automate the bond configuration on one or multiple hosts.
3.1. UNDERSTANDING THE DEFAULT BEHAVIOR OF CONTROLLER
AND PORT INTERFACES
Consider the following default behavior when managing or troubleshooting team or bond port
interfaces using the NetworkManager service:
Starting the controller interface does not automatically start the port interfaces.
Starting a port interface always starts the controller interface.
Stopping the controller interface also stops the port interface.
A controller without ports can start static IP connections.
A controller without ports waits for ports when starting DHCP connections.
A controller with a DHCP connection waiting for ports completes when you add a port with a
carrier.
A controller with a DHCP connection waiting for ports continues waiting when you add a port
without carrier.
3.2. UPSTREAM SWITCH CONFIGURATION DEPENDING ON THE
BONDING MODES
Depending on the bonding mode you want to use, you must configure the ports on the switch:
Bonding mode Configuration on the switch
0 - balance-rr Requires static EtherChannel enabled, not Link Aggregation
Control Protocol (LACP)-negotiated.
CHAPTER 3. CONFIGURING A NETWORK BOND
51
1 - active-backup No configuration required on the switch.
2 - balance-xor Requires static EtherChannel enabled, not LACP-negotiated.
3 - broadcast Requires static EtherChannel enabled, not LACP-negotiated.
4 - 802.3ad Requires LACP-negotiated EtherChannel enabled.
5 - balance-tlb No configuration required on the switch.
6 - balance-alb No configuration required on the switch.
Bonding mode Configuration on the switch
For details how to configure your switch, see the documentation of the switch.
IMPORTANT
Certain network bonding features, such as the fail-over mechanism, do not support direct
cable connections without a network switch. For further details, see the Is bonding
supported with direct connection using crossover cables? KCS solution.
3.3. CONFIGURING A NETWORK BOND BY USING NMCLI
To configure a network bond on the command line, use the nmcli utility.
Prerequisites
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports of the bond, the physical or virtual Ethernet devices must be
installed on the server.
To use team, bridge, or VLAN devices as ports of the bond, you can either create these devices
while you create the bond or you can create them in advance as described in:
Configuring a network team by using nmcli
Configuring a network bridge by using nmcli
Configuring VLAN tagging by using nmcli
Procedure
1. Create a bond interface:
# nmcli connection add type bond con-name bond0 ifname bond0 bond.options
"mode=active-backup"
This command creates a bond named bond0 that uses the active-backup mode.
Red Hat Enterprise Linux 9 Configuring and managing networking
52
To additionally set a Media Independent Interface (MII) monitoring interval, add the
miimon=interval option to the bond.options property, for example:
# nmcli connection add type bond con-name bond0 ifname bond0 bond.options
"mode=active-backup,miimon=1000"
2. Display the network interfaces, and note names of interfaces you plan to add to the bond:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp7s0 ethernet disconnected --
enp8s0 ethernet disconnected --
bridge0 bridge connected bridge0
bridge1 bridge connected bridge1
...
In this example:
enp7s0 and enp8s0 are not configured. To use these devices as ports, add connection
profiles in the next step.
bridge0 and bridge1 have existing connection profiles. To use these devices as ports,
modify their profiles in the next step.
3. Assign interfaces to the bond:
a. If the interfaces you want to assign to the bond are not configured, create new connection
profiles for them:
# nmcli connection add type ethernet port-type bond con-name bond0-port1
ifname enp7s0 controller bond0
# nmcli connection add type ethernet port-type bond con-name bond0-port2
ifname enp8s0 controller bond0
These commands create profiles for enp7s0 and enp8s0, and add them to the bond0
connection.
b. To assign an existing connection profile to the bond:
i. Set the controller parameter of these connections to bond0:
# nmcli connection modify bridge0 controller bond0
# nmcli connection modify bridge1 controller bond0
These commands assign the existing connection profiles named bridge0 and bridge1
to the bond0 connection.
ii. Reactivate the connections:
# nmcli connection up bridge0
# nmcli connection up bridge1
4. Configure the IPv4 settings:
To use this bond device as a port of other devices, enter:
CHAPTER 3. CONFIGURING A NETWORK BOND
53
# nmcli connection modify bond0 ipv4.method disabled
To use DHCP, no action is required.
To set a static IPv4 address, network mask, default gateway, and DNS server to the bond0
connection, enter:
# nmcli connection modify bond0 ipv4.addresses '192.0.2.1/24' ipv4.gateway
'192.0.2.254' ipv4.dns '192.0.2.253' ipv4.dns-search 'example.com' ipv4.method
manual
5. Configure the IPv6 settings:
To use this bond device as a port of other devices, enter:
# nmcli connection modify bond0 ipv6.method disabled
To use stateless address autoconfiguration (SLAAC), no action is required.
To set a static IPv6 address, network mask, default gateway, and DNS server to the bond0
connection, enter:
# nmcli connection modify bond0 ipv6.addresses '2001:db8:1::1/64' ipv6.gateway
'2001:db8:1::fffe' ipv6.dns '2001:db8:1::fffd' ipv6.dns-search 'example.com'
ipv6.method manual
6. Optional: If you want to set any parameters on the bond ports, use the following command:
# nmcli connection modify bond0-port1 bond-port.<parameter> <value>
7. Activate the connection:
# nmcli connection up bond0
8. Verify that the ports are connected, and the CONNECTION column displays the port’s
connection name:
# nmcli device
DEVICE TYPE STATE CONNECTION
...
enp7s0 ethernet connected bond0-port1
enp8s0 ethernet connected bond0-port2
When you activate any port of the connection, NetworkManager also activates the bond, but not
the other ports of it. You can configure that Red Hat Enterprise Linux enables all ports
automatically when the bond is enabled:
a. Enable the connection.autoconnect-ports parameter of the bond’s connection:
# nmcli connection modify bond0 connection.autoconnect-ports 1
b. Reactivate the bridge:
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54
# nmcli connection up bond0
Verification
1. Temporarily remove the network cable from one of the network devices and check if the other
device in the bond handling the traffic.
Note that there is no method to properly test link failure events using software utilities. Tools
that deactivate connections, such as nmcli, show only the bonding driver’s ability to handle port
configuration changes and not actual link failure events.
2. Display the status of the bond:
# cat /proc/net/bonding/bond0
3.4. CONFIGURING A NETWORK BOND BY USING THE RHEL WEB
CONSOLE
Use the RHEL web console to configure a network bond if you prefer to manage network settings using
a web browser-based interface.
Prerequisites
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as members of the bond, the physical or virtual Ethernet devices must
be installed on the server.
To use team, bridge, or VLAN devices as members of the bond, create them in advance as
described in:
Configuring a network team by using the RHEL web console
Configuring a network bridge by using the RHEL web console
Configuring VLAN tagging by using the RHEL web console
You have installed the RHEL 9 web console.
For instructions, see Installing and enabling the web console .
Procedure
1. Log in to the RHEL 9 web console.
For details, see Logging in to the web console .
2. Select the Networking tab in the navigation on the left side of the screen.
3. Click Add bond in the Interfaces section.
4. Enter the name of the bond device you want to create.
5. Select the interfaces that should be members of the bond.
6. Select the mode of the bond.
If you select Active backup, the web console shows the additional field Primary in which you
CHAPTER 3. CONFIGURING A NETWORK BOND
55
If you select Active backup, the web console shows the additional field Primary in which you
can select the preferred active device.
7. Set the link monitoring mode. For example, when you use the Adaptive load balancing mode,
set it to ARP.
8. Optional: Adjust the monitoring interval, link up delay, and link down delay settings. Typically,
you only change the defaults for troubleshooting purposes.
9. Click Apply.
10. By default, the bond uses a dynamic IP address. If you want to set a static IP address:
a. Click the name of the bond in the Interfaces section.
Red Hat Enterprise Linux 9 Configuring and managing networking
56
b. Click Edit next to the protocol you want to configure.
c. Select Manual next to Addresses, and enter the IP address, prefix, and default gateway.
d. In the DNS section, click the + button, and enter the IP address of the DNS server. Repeat
this step to set multiple DNS servers.
e. In the DNS search domains section, click the + button, and enter the search domain.
f. If the interface requires static routes, configure them in the Routes section.
g. Click Apply
Verification
1. Select the Networking tab in the navigation on the left side of the screen, and check if there is
incoming and outgoing traffic on the interface:
2. Temporarily remove the network cable from one of the network devices and check if the other
device in the bond handling the traffic.
CHAPTER 3. CONFIGURING A NETWORK BOND
57
Note that there is no method to properly test link failure events using software utilities. Tools
that deactivate connections, such as the web console, show only the bonding driver’s ability to
handle member configuration changes and not actual link failure events.
3. Display the status of the bond:
# cat /proc/net/bonding/bond0
3.5. CONFIGURING A NETWORK BOND BY USING NMTUI
The nmtui application provides a text-based user interface for NetworkManager. You can use nmtui to
configure a network bond on a host without a graphical interface.
NOTE
In nmtui:
Navigate by using the cursor keys.
Press a button by selecting it and hitting Enter.
Select and clear checkboxes by using Space.
Prerequisites
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports of the bond, the physical or virtual Ethernet devices must be
installed on the server.
Procedure
1. If you do not know the network device names on which you want configure a network bond,
display the available devices:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp7s0 ethernet unavailable --
enp8s0 ethernet unavailable --
...
2. Start nmtui:
# nmtui
3. Select Edit a connection, and press Enter.
4. Press Add.
5. Select Bond from the list of network types, and press Enter.
6. Optional: Enter a name for the NetworkManager profile to be created.
On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a
profile.
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58
7. Enter the bond device name to be created into the Device field.
8. Add ports to the bond to be created:
a. Press Add next to the Slaves list.
b. Select the type of the interface you want to add as port to the bond, for example, Ethernet.
c. Optional: Enter a name for the NetworkManager profile to be created for this bond port.
d. Enter the port’s device name into the Device field.
e. Press OK to return to the window with the bond settings.
Figure 3.1. Adding an Ethernet device as port to a bond
f. Repeat these steps to add more ports to the bond.
9. Set the bond mode. Depending on the value you set, nmtui displays additional fields for settings
that are related to the selected mode.
10. Depending on your environment, configure the IP address settings in the IPv4 configuration
and IPv6 configuration areas accordingly. For this, press the button next to these areas, and
select:
Disabled, if the bond does not require an IP address.
Automatic, if a DHCP server or stateless address autoconfiguration (SLAAC) dynamically
assigns an IP address to the bond.
Manual, if the network requires static IP address settings. In this case, you must fill further
fields:
i. Press Show next to the protocol you want to configure to display additional fields.
ii. Press Add next to Addresses, and enter the IP address and the subnet mask in
Classless Inter-Domain Routing (CIDR) format.
If you do not specify a subnet mask, NetworkManager sets a /32 subnet mask for IPv4
addresses and /64 for IPv6 addresses.
iii. Enter the address of the default gateway.
iv. Press Add next to DNS servers, and enter the DNS server address.
CHAPTER 3. CONFIGURING A NETWORK BOND
59
v. Press Add next to Search domains, and enter the DNS search domain.
Figure 3.2. Example of a bond connection with static IP address settings
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60
11. Press OK to create and automatically activate the new connection.
12. Press Back to return to the main menu.
13. Select Quit, and press Enter to close the nmtui application.
Verification
1. Temporarily remove the network cable from one of the network devices and check if the other
device in the bond handling the traffic.
Note that there is no method to properly test link failure events using software utilities. Tools
that deactivate connections, such as nmcli, show only the bonding driver’s ability to handle port
configuration changes and not actual link failure events.
2. Display the status of the bond:
# cat /proc/net/bonding/bond0
3.6. CONFIGURING A NETWORK BOND BY USING NM-CONNECTION-
EDITOR
If you use Red Hat Enterprise Linux with a graphical interface, you can configure network bonds using
the nm-connection-editor application.
Note that nm-connection-editor can add only new ports to a bond. To use an existing connection
profile as a port, create the bond by using the nmcli utility as described in Configuring a network bond
by using nmcli.
Prerequisites
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports of the bond, the physical or virtual Ethernet devices must be
installed on the server.
To use team, bond, or VLAN devices as ports of the bond, ensure that these devices are not
already configured.
Procedure
1. Open a terminal, and enter nm-connection-editor:
$ nm-connection-editor
2. Click the + button to add a new connection.
3. Select the Bond connection type, and click Create.
4. On the Bond tab:
a. Optional: Set the name of the bond interface in the Interface name field.
b. Click the Add button to add a network interface as a port to the bond.
i. Select the connection type of the interface. For example, select Ethernet for a wired
CHAPTER 3. CONFIGURING A NETWORK BOND
61
i. Select the connection type of the interface. For example, select Ethernet for a wired
connection.
ii. Optional: Set a connection name for the port.
iii. If you create a connection profile for an Ethernet device, open the Ethernet tab, and
select in the Device field the network interface you want to add as a port to the bond. If
you selected a different device type, configure it accordingly. Note that you can only
use Ethernet interfaces in a bond that are not configured.
iv. Click Save.
c. Repeat the previous step for each interface you want to add to the bond:
d. Optional: Set other options, such as the Media Independent Interface (MII) monitoring
interval.
5. Configure the IP address settings on both the IPv4 Settings and IPv6 Settings tabs:
To use this bridge device as a port of other devices, set the Method field to Disabled.
To use DHCP, leave the Method field at its default, Automatic (DHCP).
To use static IP settings, set the Method field to Manual and fill the fields accordingly:
6. Click Save.
7. Close nm-connection-editor.
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62
Verification
1. Temporarily remove the network cable from one of the network devices and check if the other
device in the bond handling the traffic.
Note that there is no method to properly test link failure events using software utilities. Tools
that deactivate connections, such as nmcli, show only the bonding driver’s ability to handle port
configuration changes and not actual link failure events.
2. Display the status of the bond:
# cat /proc/net/bonding/bond0
Additional resources
Configuring NetworkManager to avoid using a specific profile to provide a default gateway
Configuring a network team by using nm-connection-editor
Configuring a network bridge by using nm-connection-editor
Configuring VLAN tagging by using nm-connection-editor
3.7. CONFIGURING A NETWORK BOND BY USING NMSTATECTL
Use the nmstatectl utility to configure a network bond through the Nmstate API. The Nmstate API
ensures that, after setting the configuration, the result matches the configuration file. If anything fails,
nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.
Depending on your environment, adjust the YAML file accordingly. For example, to use different devices
than Ethernet adapters in the bond, adapt the base-iface attribute and type attributes of the ports you
use in the bond.
Prerequisites
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports in the bond, the physical or virtual Ethernet devices must be
installed on the server.
To use team, bridge, or VLAN devices as ports in the bond, set the interface name in the port
list, and define the corresponding interfaces.
The nmstate package is installed.
Procedure
1. Create a YAML file, for example ~/create-bond.yml, with the following content:
---
interfaces:
- name: bond0
type: bond
state: up
ipv4:
enabled: true
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63
These settings define a network bond with the following settings:
Network interfaces in the bond: enp1s0 and enp7s0
Mode: active-backup
Static IPv4 address: 192.0.2.1 with a /24 subnet mask
Static IPv6 address: 2001:db8:1::1 with a /64 subnet mask
IPv4 default gateway: 192.0.2.254
IPv6 default gateway: 2001:db8:1::fffe
IPv4 DNS server: 192.0.2.200
IPv6 DNS server: 2001:db8:1::ffbb
address:
- ip: 192.0.2.1
prefix-length: 24
dhcp: false
ipv6:
enabled: true
address:
- ip: 2001:db8:1::1
prefix-length: 64
autoconf: false
dhcp: false
link-aggregation:
mode: active-backup
port:
- enp1s0
- enp7s0
- name: enp1s0
type: ethernet
state: up
- name: enp7s0
type: ethernet
state: up
routes:
config:
- destination: 0.0.0.0/0
next-hop-address: 192.0.2.254
next-hop-interface: bond0
- destination: ::/0
next-hop-address: 2001:db8:1::fffe
next-hop-interface: bond0
dns-resolver:
config:
search:
- example.com
server:
- 192.0.2.200
- 2001:db8:1::ffbb
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DNS search domain: example.com
2. Apply the settings to the system:
# nmstatectl apply ~/create-bond.yml
Verification
1. Display the status of the devices and connections:
# nmcli device status
DEVICE TYPE STATE CONNECTION
bond0 bond connected bond0
2. Display all settings of the connection profile:
# nmcli connection show bond0
connection.id: bond0
connection.uuid: 79cbc3bd-302e-4b1f-ad89-f12533b818ee
connection.stable-id: --
connection.type: bond
connection.interface-name: bond0
...
3. Display the connection settings in YAML format:
# nmstatectl show bond0
Additional resources
nmstatectl(8) man page
/usr/share/doc/nmstate/examples/ directory
3.8. CONFIGURING A NETWORK BOND BY USING THE NETWORK
RHEL SYSTEM ROLE
You can combine network interfaces in a bond to provide a logical interface with higher throughput or
redundancy. To configure a bond, create a NetworkManager connection profile. By using Ansible and the
network RHEL system role, you can automate this process and remotely configure connection profiles
on the hosts defined in a playbook.
You can use the network RHEL system role to configure a network bond and, if a connection profile for
the bond’s parent device does not exist, the role can create it as well.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
CHAPTER 3. CONFIGURING A NETWORK BOND
65
Two or more physical or virtual network devices are installed on the server.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
The settings specified in the example playbook include the following:
type: <profile_type>
Sets the type of the profile to create. The example playbook creates three connection
profiles: One for the bond and two for the Ethernet devices.
dhcp4: yes
Enables automatic IPv4 address assignment from DHCP, PPP, or similar services.
auto6: yes
Enables IPv6 auto-configuration. By default, NetworkManager uses Router Advertisements.
If the router announces the managed flag, NetworkManager requests an IPv6 address and
prefix from a DHCPv6 server.
mode: <bond_mode>
Sets the bonding mode. Possible values are:
balance-rr (default)
---
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: Bond connection profile with two Ethernet ports
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
# Bond profile
- name: bond0
type: bond
interface_name: bond0
ip:
dhcp4: yes
auto6: yes
bond:
mode: active-backup
state: up
# Port profile for the 1st Ethernet device
- name: bond0-port1
interface_name: enp7s0
type: ethernet
controller: bond0
state: up
# Port profile for the 2nd Ethernet device
- name: bond0-port2
interface_name: enp8s0
type: ethernet
controller: bond0
state: up
Red Hat Enterprise Linux 9 Configuring and managing networking
66
balance-rr (default)
active-backup
balance-xor
broadcast
802.3ad
balance-tlb
balance-alb.
Depending on the mode you set, you need to set additional variables in the playbook.
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
Temporarily remove the network cable from one of the network devices and check if the other
device in the bond handling the traffic.
Note that there is no method to properly test link failure events using software utilities. Tools
that deactivate connections, such as nmcli, show only the bonding driver’s ability to handle port
configuration changes and not actual link failure events.
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
3.9. CREATING A NETWORK BOND TO ENABLE SWITCHING BETWEEN
AN ETHERNET AND WIRELESS CONNECTION WITHOUT
INTERRUPTING THE VPN
RHEL users who connect their workstation to their company’s network typically use a VPN to access
remote resources. However, if the workstation switches between an Ethernet and Wi-Fi connection, for
example, if you release a laptop from a docking station with an Ethernet connection, the VPN connection
is interrupted. To avoid this problem, you can create a network bond that uses the Ethernet and Wi-Fi
connection in active-backup mode.
CHAPTER 3. CONFIGURING A NETWORK BOND
67
Prerequisites
The host contains an Ethernet and a Wi-Fi device.
An Ethernet and Wi-Fi NetworkManager connection profile has been created and both
connections work independently.
This procedure uses the following connection profiles to create a network bond named bond0:
Docking_station associated with the enp11s0u1 Ethernet device
Wi-Fi associated with the wlp1s0 Wi-Fi device
Procedure
1. Create a bond interface in active-backup mode:
# nmcli connection add type bond con-name bond0 ifname bond0 bond.options
"mode=active-backup"
This command names both the interface and connection profile bond0.
2. Configure the IPv4 settings of the bond:
If a DHCP server in your network assigns IPv4 addresses to hosts, no action is required.
If your local network requires static IPv4 addresses, set the address, network mask, default
gateway, DNS server, and DNS search domain to the bond0 connection:
# nmcli connection modify bond0 ipv4.addresses '192.0.2.1/24'
# nmcli connection modify bond0 ipv4.gateway '192.0.2.254'
# nmcli connection modify bond0 ipv4.dns '192.0.2.253'
# nmcli connection modify bond0 ipv4.dns-search 'example.com'
# nmcli connection modify bond0 ipv4.method manual
3. Configure the IPv6 settings of the bond:
If your router or a DHCP server in your network assigns IPv6 addresses to hosts, no action is
required.
If your local network requires static IPv6 addresses, set the address, network mask, default
gateway, DNS server, and DNS search domain to the bond0 connection:
# nmcli connection modify bond0 ipv6.addresses '2001:db8:1::1/64'
# nmcli connection modify bond0 ipv6.gateway '2001:db8:1::fffe'
# nmcli connection modify bond0 ipv6.dns '2001:db8:1::fffd'
# nmcli connection modify bond0 ipv6.dns-search 'example.com'
# nmcli connection modify bond0 ipv6.method manual
4. Display the connection profiles:
# nmcli connection show
NAME UUID TYPE DEVICE
Docking_station 256dd073-fecc-339d-91ae-9834a00407f9 ethernet enp11s0u1
Wi-Fi 1f1531c7-8737-4c60-91af-2d21164417e8 wifi wlp1s0
...
Red Hat Enterprise Linux 9 Configuring and managing networking
68
You require the names of the connection profiles and the Ethernet device name in the next
steps.
5. Assign the connection profile of the Ethernet connection to the bond:
# nmcli connection modify Docking_station controller bond0
6. Assign the connection profile of the Wi-Fi connection to the bond:
# nmcli connection modify Wi-Fi controller bond0
7. If your Wi-Fi network uses MAC filtering to allow only MAC addresses on a allow list to access
the network, configure that NetworkManager dynamically assigns the MAC address of the
active port to the bond:
# nmcli connection modify bond0 +bond.options fail_over_mac=1
With this setting, you must set only the MAC address of the Wi-Fi device to the allow list instead
of the MAC address of both the Ethernet and Wi-Fi device.
8. Set the device associated with the Ethernet connection as primary device of the bond:
# nmcli con modify bond0 +bond.options "primary=enp11s0u1"
With this setting, the bond always uses the Ethernet connection if it is available.
9. Configure that NetworkManager automatically activates ports when the bond0 device is
activated:
# nmcli connection modify bond0 connection.autoconnect-ports 1
10. Activate the bond0 connection:
# nmcli connection up bond0
Verification
Display the currently active device, the status of the bond and its ports:
# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.7.1 (April 27, 2011)
Bonding Mode: fault-tolerance (active-backup) (fail_over_mac active)
Primary Slave: enp11s0u1 (primary_reselect always)
Currently Active Slave: enp11s0u1
MII Status: up
MII Polling Interval (ms): 1
Up Delay (ms): 0
Down Delay (ms): 0
Peer Notification Delay (ms): 0
Slave Interface: enp11s0u1
MII Status: up
Speed: 1000 Mbps
CHAPTER 3. CONFIGURING A NETWORK BOND
69
Duplex: full
Link Failure Count: 0
Permanent HW addr: 00:53:00:59:da:b7
Slave queue ID: 0
Slave Interface: wlp1s0
MII Status: up
Speed: Unknown
Duplex: Unknown
Link Failure Count: 2
Permanent HW addr: 00:53:00:b3:22:ba
Slave queue ID: 0
Additional resources
Configuring an Ethernet connection
Managing Wi-Fi connections
Configuring a network bond
3.10. THE DIFFERENT NETWORK BONDING MODES
The Linux bonding driver provides link aggregation. Bonding is the process of aggregating multiple
network interfaces in parallel to provide a single logical bonded interface. The actions of a bonded
interface depend on the bonding policy that is also known as mode. The different modes provide either
load-balancing or hot standby services.
The following modes exist:
Balance-rr (Mode 0)
Balance-rr uses the round-robin algorithm that sequentially transmits packets from the first
available port to the last one. This mode provides load balancing and fault tolerance.
This mode requires switch configuration of a port aggregation group, also called EtherChannel or
similar port grouping. An EtherChannel is a port link aggregation technology to group multiple
physical Ethernet links to one logical Ethernet link.
The drawback of this mode is that it is not suitable for heavy workloads and if TCP throughput or
ordered packet delivery is essential.
Active-backup (Mode 1)
Active-backup uses the policy that determines that only one port is active in the bond. This mode
provides fault tolerance and does not require any switch configuration.
If the active port fails, an alternate port becomes active. The bond sends a gratuitous address
resolution protocol (ARP) response to the network. The gratuitous ARP forces the receiver of the
ARP frame to update their forwarding table. The Active-backup mode transmits a gratuitous ARP to
announce the new path to maintain connectivity for the host.
The primary option defines the preferred port of the bonding interface.
Balance-xor (Mode 2)
Balance-xor uses the selected transmit hash policy to send the packets. This mode provides load
balancing, fault tolerance, and requires switch configuration to set up an Etherchannel or similar port
grouping.
Red Hat Enterprise Linux 9 Configuring and managing networking
70
To alter packet transmission and balance transmit, this mode uses the xmit_hash_policy option.
Depending on the source or destination of traffic on the interface, the interface requires an
additional load-balancing configuration. See description xmit_hash_policy bonding parameter.
Broadcast (Mode 3)
Broadcast uses a policy that transmits every packet on all interfaces. This mode provides fault
tolerance and requires a switch configuration to set up an EtherChannel or similar port grouping.
The drawback of this mode is that it is not suitable for heavy workloads and if TCP throughput or
ordered packet delivery is essential.
802.3ad (Mode 4)
802.3ad uses the same-named IEEE standard dynamic link aggregation policy. This mode provides
fault tolerance. This mode requires switch configuration to set up a Link Aggregation Control
Protocol (LACP) port grouping.
This mode creates aggregation groups that share the same speed and duplex settings and utilizes all
ports in the active aggregator. Depending on the source or destination of traffic on the interface,
this mode requires an additional load-balancing configuration.
By default, the port selection for outgoing traffic depends on the transmit hash policy. Use the
xmit_hash_policy option of the transmit hash policy to change the port selection and balance
transmit.
The difference between the 802.3ad and the Balance-xor is compliance. The 802.3ad policy
negotiates LACP between the port aggregation groups. See description xmit_hash_policy bonding
parameter
Balance-tlb (Mode 5)
Balance-tlb uses the transmit load balancing policy. This mode provides fault tolerance, load
balancing, and establishes channel bonding that does not require any switch support.
The active port receives the incoming traffic. In case of failure of the active port, another one takes
over the MAC address of the failed port. To decide which interface processes the outgoing traffic,
use one of the following modes:
Value 0: Uses the hash distribution policy to distribute traffic without load balancing
Value 1: Distributes traffic to each port by using load balancing
With the bonding option tlb_dynamic_lb=0, this bonding mode uses the xmit_hash_policy
bonding option to balance transmit. The primary option defines the preferred port of the
bonding interface.
See description xmit_hash_policy bonding parameter.
Balance-alb (Mode 6)
Balance-alb uses an adaptive load balancing policy. This mode provides fault tolerance, load
balancing, and does not require any special switch support.
This mode Includes balance-transmit load balancing (balance-tlb) and receive-load balancing for
IPv4 and IPv6 traffic. The bonding intercepts ARP replies sent by the local system and overwrites the
source hardware address of one of the ports in the bond. ARP negotiation manages the receive-load
balancing. Therefore, different ports use different hardware addresses for the server.
The primary option defines the preferred port of the bonding interface. With the bonding option
tlb_dynamic_lb=0, this bonding mode uses the xmit_hash_policy bonding option to balance
transmit. See description xmit_hash_policy bonding parameter.
CHAPTER 3. CONFIGURING A NETWORK BOND
71
Additional resources
/usr/share/doc/kernel-doc-<version>/Documentation/networking/bonding.rst provided by
the kernel-doc package
/usr/share/doc/kernel-doc-<version>/Documentation/networking/bonding.txt provided by
the kernel-doc package
Which bonding modes work when used with a bridge that virtual machine guests or containers
connect to?
How are the values for different policies in "xmit_hash_policy" bonding parameter calculated?
3.11. THE XMIT_HASH_POLICY BONDING PARAMETER
The xmit_hash_policy load balancing parameter selects the transmit hash policy for a node selection in
the balance-xor, 802.3ad, balance-alb, and balance-tlb modes. It is only applicable to mode 5 and 6 if
the tlb_dynamic_lb parameter is 0. The possible values of this parameter are layer2, layer2+3,
layer3+4, encap2+3, encap3+4, and vlan+srcmac.
Refer the table for details:
Policy or
Network
layers
Layer2 Layer2+3 Layer3+4 encap2+3 encap3+4 VLAN+src
mac
Uses XOR of
source and
destination
MAC
addresses
and
Ethernet
protocol
type
XOR of
source and
destination
MAC
addresses
and IP
addresses
XOR of
source and
destination
ports and IP
addresses
XOR of
source and
destination
MAC
addresses
and IP
addresses
inside a
supported
tunnel, for
example,
Virtual
Extensible
LAN
(VXLAN).
This mode
relies on
skb_flow_
dissect()
function to
obtain the
header
fields
XOR of
source and
destination
ports and IP
addresses
inside a
supported
tunnel, for
example,
VXLAN.
This mode
relies on
skb_flow_
dissect()
function to
obtain the
header
fields
XOR of
VLAN ID
and source
MAC
vendor and
source MAC
device
Red Hat Enterprise Linux 9 Configuring and managing networking
72
Placement
of traffic
All traffic to
a particular
network
peer on the
same
underlying
network
interface
All traffic to
a particular
IP address
on the same
underlying
network
interface
All traffic to
a particular
IP address
and port on
the same
underlying
network
interface
Primary
choice
If network
traffic is
between
this system
and multiple
other
systems in
the same
broadcast
domain
If network
traffic
between
this system
and multiple
other
systems
goes
through a
default
gateway
If network
traffic
between
this system
and another
system uses
the same IP
addresses
but goes
through
multiple
ports
The
encapsulate
d traffic is
between
the source
system and
multiple
other
systems
using
multiple IP
addresses
The
encapsulate
d traffic is
between
the source
system and
other
systems
using
multiple
port
numbers
If the bond
carries
network
traffic, from
multiple
containers
or virtual
machines
(VM), that
expose their
MAC
address
directly to
the external
network
such as the
bridge
network,
and you can
not
configure a
switch for
Mode 2 or
Mode 4
Secondary
choice
If network
traffic is
mostly
between
this system
and multiple
other
systems
behind a
default
gateway
If network
traffic is
mostly
between
this system
and another
system
Compliant 802.3ad 802.3ad Not
802.3ad
CHAPTER 3. CONFIGURING A NETWORK BOND
73
Default
policy
This is the
default
policy if no
configuratio
n is
provided
For non-IP
traffic, the
formula is
the same as
for the
layer2
transmit
policy
For non-IP
traffic, the
formula is
the same as
for the
layer2
transmit
policy
Red Hat Enterprise Linux 9 Configuring and managing networking
74
CHAPTER 4. CONFIGURING A NIC TEAM
Network interface controller (NIC) teaming is a method to combine or aggregate physical and virtual
network interfaces to provide a logical interface with higher throughput or redundancy. NIC teaming
uses a small kernel module to implement fast handling of packet flows and a user-space service for
other tasks. This way, NIC teaming is an easily extensible and scalable solution for load-balancing and
redundancy requirements.
Red Hat Enterprise Linux provides administrators different options to configure team devices. For
example:
Use nmcli to configure teams connections using the command line.
Use the RHEL web console to configure team connections using a web browser.
Use the nm-connection-editor application to configure team connections in a graphical
interface.
IMPORTANT
NIC teaming is deprecated in Red Hat Enterprise Linux 9. Consider using the network
bonding driver as an alternative. For details, see Configuring a network bond .
4.1. MIGRATING A NIC TEAM CONFIGURATION TO NETWORK BOND
Network interface controller (NIC) teaming is deprecated in Red Hat Enterprise Linux 9. If you already
have a working NIC team configured, for example because you upgraded from an earlier RHEL version,
you can migrate the configuration to a network bond that is managed by NetworkManager.
IMPORTANT
The team2bond utility only converts the team configuration to a bond. Afterwards, you
must manually configure further settings of the bond, such as IP addresses and DNS
configuration.
Prerequisites
The team-team0 NetworkManager connection profile is configured and manages the team0
device.
The teamd package is installed.
Procedure
1. Optional: Display the IP configuration of the team-team0 NetworkManager connection:
# nmcli connection show team-team0 | egrep "^ip"
...
ipv4.method: manual
ipv4.dns: 192.0.2.253
ipv4.dns-search: example.com
ipv4.addresses: 192.0.2.1/24
ipv4.gateway: 192.0.2.254
...
CHAPTER 4. CONFIGURING A NIC TEAM
75
ipv6.method: manual
ipv6.dns: 2001:db8:1::fffd
ipv6.dns-search: example.com
ipv6.addresses: 2001:db8:1::1/64
ipv6.gateway: 2001:db8:1::fffe
...
2. Export the configuration of the team0 device to a JSON file:
# teamdctl team0 config dump actual > /tmp/team0.json
3. Remove the NIC team. For example, if you configured the team in NetworkManager, remove the
team-team0 connection profile and the profiles of associated ports:
# nmcli connection delete team-team0
# nmcli connection delete team-team0-port1
# nmcli connection delete team-team0-port2
4. Run the team2bond utility in dry-run mode to display nmcli commands that set up a network
bond with similar settings as the team device:
# team2bond --config=/tmp/team0.json --rename=bond0
nmcli con add type bond ifname bond0 bond.options "mode=active-
backup,num_grat_arp=1,num_unsol_na=1,resend_igmp=1,miimon=100,miimon=100"
nmcli con add type ethernet ifname enp7s0 controller bond0
nmcli con add type ethernet ifname enp8s0 controller bond0
The first command contains two miimon options because the team configuration file contained
two link_watch entries. Note that this does not affect the creation of the bond.
If you bound services to the device name of the team and want to avoid updating or breaking
these services, omit the --rename=bond0 option. In this case, team2bond uses the same
interface name for the bond as for the team.
5. Verify that the options for the bond the team2bond utility suggested are correct.
6. Create the bond. You can execute the suggested nmcli commands or re-run the team2bond
command with the --exec-cmd option:
# team2bond --config=/tmp/team0.json --rename=bond0 --exec-cmd
Connection 'bond-bond0' (0241a531-0c72-4202-80df-73eadfc126b5) successfully added.
Connection 'bond-port-enp7s0' (38489729-b624-4606-a784-1ccf01e2f6d6) successfully
added.
Connection 'bond-port-enp8s0' (de97ec06-7daa-4298-9a71-9d4c7909daa1) successfully
added.
You require the name of the bond connection profile (bond-bond0) in the next steps.
7. Set the IPv4 settings that were previously configured on team-team0 to the bond-bond0
connection:
# nmcli connection modify bond-bond0 ipv4.addresses '192.0.2.1/24'
# nmcli connection modify bond-bond0 ipv4.gateway '192.0.2.254'
# nmcli connection modify bond-bond0 ipv4.dns '192.0.2.253'
Red Hat Enterprise Linux 9 Configuring and managing networking
76
# nmcli connection modify bond-bond0 ipv4.dns-search 'example.com'
# nmcli connection modify bond-bond0 ipv4.method manual
8. Set the IPv6 settings that were previously configured on team-team0 to the bond-bond0
connection:
# nmcli connection modify bond-bond0 ipv6.addresses '2001:db8:1::1/64'
# nmcli connection modify bond-bond0 ipv6.gateway '2001:db8:1::fffe'
# nmcli connection modify bond-bond0 ipv6.dns '2001:db8:1::fffd'
# nmcli connection modify bond-bond0 ipv6.dns-search 'example.com'
# nmcli connection modify bond-bond0 ipv6.method manual
9. Activate the connection:
# nmcli connection up bond-bond0
Verification
1. Display the IP configuration of the bond-bond0 NetworkManager connection:
# nmcli connection show bond-bond0 | egrep "^ip"
...
ipv4.method: manual
ipv4.dns: 192.0.2.253
ipv4.dns-search: example.com
ipv4.addresses: 192.0.2.1/24
ipv4.gateway: 192.0.2.254
...
ipv6.method: manual
ipv6.dns: 2001:db8:1::fffd
ipv6.dns-search: example.com
ipv6.addresses: 2001:db8:1::1/64
ipv6.gateway: 2001:db8:1::fffe
...
2. Display the status of the bond:
# cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v5.13.0-0.rc7.51.el9.x86_64
Bonding Mode: fault-tolerance (active-backup)
Primary Slave: None
Currently Active Slave: enp7s0
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0
Peer Notification Delay (ms): 0
Slave Interface: enp7s0
MII Status: up
Speed: Unknown
Duplex: Unknown
Link Failure Count: 0
CHAPTER 4. CONFIGURING A NIC TEAM
77
Permanent HW addr: 52:54:00:bf:b1:a9
Slave queue ID: 0
Slave Interface: enp8s0
MII Status: up
Speed: Unknown
Duplex: Unknown
Link Failure Count: 0
Permanent HW addr: 52:54:00:04:36:0f
Slave queue ID: 0
In this example, both ports are up.
3. To verify that bonding failover works:
a. Temporarily remove the network cable from the host. Note that there is no method to
properly test link failure events using the command line.
b. Display the status of the bond:
# cat /proc/net/bonding/bond0
4.2. UNDERSTANDING THE DEFAULT BEHAVIOR OF CONTROLLER
AND PORT INTERFACES
Consider the following default behavior when managing or troubleshooting team or bond port
interfaces using the NetworkManager service:
Starting the controller interface does not automatically start the port interfaces.
Starting a port interface always starts the controller interface.
Stopping the controller interface also stops the port interface.
A controller without ports can start static IP connections.
A controller without ports waits for ports when starting DHCP connections.
A controller with a DHCP connection waiting for ports completes when you add a port with a
carrier.
A controller with a DHCP connection waiting for ports continues waiting when you add a port
without carrier.
4.3. UNDERSTANDING THE TEAMD SERVICE, RUNNERS, AND LINK-
WATCHERS
The team service, teamd, controls one instance of the team driver. This instance of the driver adds
instances of a hardware device driver to form a team of network interfaces. The team driver presents a
network interface, for example team0, to the kernel.
The teamd service implements the common logic to all methods of teaming. Those functions are unique
to the different load sharing and backup methods, such as round-robin, and implemented by separate
units of code referred to as runners. Administrators specify runners in JavaScript Object Notation
Red Hat Enterprise Linux 9 Configuring and managing networking
78
(JSON) format, and the JSON code is compiled into an instance of teamd when the instance is created.
Alternatively, when using NetworkManager, you can set the runner in the team.runner parameter, and
NetworkManager auto-creates the corresponding JSON code.
The following runners are available:
broadcast: Transmits data over all ports.
roundrobin: Transmits data over all ports in turn.
activebackup: Transmits data over one port while the others are kept as a backup.
loadbalance: Transmits data over all ports with active Tx load balancing and Berkeley Packet
Filter (BPF)-based Tx port selectors.
random: Transmits data on a randomly selected port.
lacp: Implements the 802.3ad Link Aggregation Control Protocol (LACP).
The teamd services uses a link watcher to monitor the state of subordinate devices. The following link-
watchers are available:
ethtool: The libteam library uses the ethtool utility to watch for link state changes. This is the
default link-watcher.
arp_ping: The libteam library uses the arp_ping utility to monitor the presence of a far-end
hardware address using Address Resolution Protocol (ARP).
nsna_ping: On IPv6 connections, the libteam library uses the Neighbor Advertisement and
Neighbor Solicitation features from the IPv6 Neighbor Discovery protocol to monitor the
presence of a neighbor’s interface.
Each runner can use any link watcher, with the exception of lacp. This runner can only use the ethtool
link watcher.
4.4. CONFIGURING A NIC TEAM BY USING NMCLI
To configure a network interface controller (NIC) team on the command line, use the nmcli utility.
IMPORTANT
NIC teaming is deprecated in Red Hat Enterprise Linux 9. Consider using the network
bonding driver as an alternative. For details, see Configuring a network bond .
Prerequisites
The teamd and NetworkManager-team packages are installed.
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports of the team, the physical or virtual Ethernet devices must be
installed on the server and connected to a switch.
To use bond, bridge, or VLAN devices as ports of the team, you can either create these devices
while you create the team or you can create them in advance as described in:
CHAPTER 4. CONFIGURING A NIC TEAM
79
Configuring a network bond by using nmcli
Configuring a network bridge by using nmcli
Configuring VLAN tagging by using nmcli
Procedure
1. Create a team interface:
# nmcli connection add type team con-name team0 ifname team0 team.runner
activebackup
This command creates a NIC team named team0 that uses the activebackup runner.
2. Optional: Set a link watcher. For example, to set the ethtool link watcher in the team0
connection profile:
# nmcli connection modify team0 team.link-watchers "name=ethtool"
Link watchers support different parameters. To set parameters for a link watcher, specify them
space-separated in the name property. Note that the name property must be surrounded by
quotation marks. For example, to use the ethtool link watcher and set its delay-up parameter to
2500 milliseconds (2.5 seconds):
# nmcli connection modify team0 team.link-watchers "name=ethtool delay-up=2500"
To set multiple link watchers and each of them with specific parameters, the link watchers must
be separated by a comma. The following example sets the ethtool link watcher with the delay-
up parameter and the arp_ping link watcher with the source-host and target-host parameter:
# nmcli connection modify team0 team.link-watchers "name=ethtool delay-up=2,
name=arp_ping source-host=192.0.2.1 target-host=192.0.2.2"
3. Display the network interfaces, and note the names of the interfaces you want to add to the
team:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp7s0 ethernet disconnected --
enp8s0 ethernet disconnected --
bond0 bond connected bond0
bond1 bond connected bond1
...
In this example:
enp7s0 and enp8s0 are not configured. To use these devices as ports, add connection
profiles in the next step. Note that you can only use Ethernet interfaces in a team that are
not assigned to any connection.
bond0 and bond1 have existing connection profiles. To use these devices as ports, modify
their profiles in the next step.
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4. Assign the port interfaces to the team:
a. If the interfaces you want to assign to the team are not configured, create new connection
profiles for them:
# nmcli connection add type ethernet port-type team con-name team0-port1 ifname
enp7s0 controller team0
# nmcli connection add type ethernet port--type team con-name team0-port2
ifname enp8s0 controller team0
These commands create profiles for enp7s0 and enp8s0, and add them to the team0
connection.
b. To assign an existing connection profile to the team:
i. Set the controller parameter of these connections to team0:
# nmcli connection modify bond0 controller team0
# nmcli connection modify bond1 controller team0
These commands assign the existing connection profiles named bond0 and bond1 to
the team0 connection.
ii. Reactivate the connections:
# nmcli connection up bond0
# nmcli connection up bond1
5. Configure the IPv4 settings:
To use this team device as a port of other devices, enter:
# nmcli connection modify team0 ipv4.method disabled
To use DHCP, no action is required.
To set a static IPv4 address, network mask, default gateway, and DNS server to the team0
connection, enter:
# nmcli connection modify team0 ipv4.addresses '192.0.2.1/24' ipv4.gateway
'192.0.2.254' ipv4.dns '192.0.2.253' ipv4.dns-search 'example.com' ipv4.method
manual
6. Configure the IPv6 settings:
To use this team device as a port of other devices, enter:
# nmcli connection modify team0 ipv6.method disabled
To use stateless address autoconfiguration (SLAAC), no action is required.
To set a static IPv6 address, network mask, default gateway, and DNS server to the team0
connection, enter:
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# nmcli connection modify team0 ipv6.addresses '2001:db8:1::1/64' ipv6.gateway
'2001:db8:1::fffe' ipv6.dns '2001:db8:1::fffd' ipv6.dns-search 'example.com'
ipv6.method manual
7. Activate the connection:
# nmcli connection up team0
Verification
Display the status of the team:
# teamdctl team0 state
setup:
runner: activebackup
ports:
enp7s0
link watches:
link summary: up
instance[link_watch_0]:
name: ethtool
link: up
down count: 0
enp8s0
link watches:
link summary: up
instance[link_watch_0]:
name: ethtool
link: up
down count: 0
runner:
active port: enp7s0
In this example, both ports are up.
Additional resources
Configuring NetworkManager to avoid using a specific profile to provide a default gateway
Understanding the teamd service, runners, and link-watchers
nm-settings(5) man page
teamd.conf(5) man page
4.5. CONFIGURING A NIC TEAM BY USING THE RHEL WEB CONSOLE
Use the RHEL web console to configure a network interface controller (NIC) team if you prefer to
manage network settings using a web browser-based interface.
IMPORTANT
NIC teaming is deprecated in Red Hat Enterprise Linux 9. Consider using the network
bonding driver as an alternative. For details, see Configuring a network bond .
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Prerequisites
The teamd and NetworkManager-team packages are installed.
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports of the team, the physical or virtual Ethernet devices must be
installed on the server and connected to a switch.
To use bond, bridge, or VLAN devices as ports of the team, create them in advance as described
in:
Configuring a network bond by using the RHEL web console
Configuring a network bridge by using the RHEL web console
Configuring VLAN tagging by using the RHEL web console
You have installed the RHEL 9 web console.
For instructions, see Installing and enabling the web console .
Procedure
1. Log in to the RHEL 9 web console.
For details, see Logging in to the web console .
2. Select the Networking tab in the navigation on the left side of the screen.
3. Click Add team in the Interfaces section.
4. Enter the name of the team device you want to create.
5. Select the interfaces that should be ports of the team.
6. Select the runner of the team.
If you select Load balancing or 802.3ad LACP, the web console shows the additional field
Balancer.
7. Set the link watcher:
If you select Ethtool, additionally, set a link up and link down delay.
If you set ARP ping or NSNA ping, additionally, set a ping interval and ping target.
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8. Click Apply.
9. By default, the team uses a dynamic IP address. If you want to set a static IP address:
a. Click the name of the team in the Interfaces section.
b. Click Edit next to the protocol you want to configure.
c. Select Manual next to Addresses, and enter the IP address, prefix, and default gateway.
d. In the DNS section, click the + button, and enter the IP address of the DNS server. Repeat
this step to set multiple DNS servers.
e. In the DNS search domains section, click the + button, and enter the search domain.
f. If the interface requires static routes, configure them in the Routes section.
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g. Click Apply
Verification
1. Select the Networking tab in the navigation on the left side of the screen, and check if there is
incoming and outgoing traffic on the interface.
2. Display the status of the team:
# teamdctl team0 state
setup:
runner: activebackup
ports:
enp7s0
link watches:
link summary: up
instance[link_watch_0]:
name: ethtool
link: up
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down count: 0
enp8s0
link watches:
link summary: up
instance[link_watch_0]:
name: ethtool
link: up
down count: 0
runner:
active port: enp7s0
In this example, both ports are up.
Additional resources
Understanding the teamd service, runners, and link-watchers
4.6. CONFIGURING A NIC TEAM BY USING NM-CONNECTION-EDITOR
If you use Red Hat Enterprise Linux with a graphical interface, you can configure network interface
controller (NIC) teams using the nm-connection-editor application.
Note that nm-connection-editor can add only new ports to a team. To use an existing connection
profile as a port, create the team using the nmcli utility as described in Configuring a NIC team by using
nmcli.
IMPORTANT
NIC teaming is deprecated in Red Hat Enterprise Linux 9. Consider using the network
bonding driver as an alternative. For details, see Configuring a network bond .
Prerequisites
The teamd and NetworkManager-team packages are installed.
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports of the team, the physical or virtual Ethernet devices must be
installed on the server.
To use team, bond, or VLAN devices as ports of the team, ensure that these devices are not
already configured.
Procedure
1. Open a terminal, and enter nm-connection-editor:
$ nm-connection-editor
2. Click the + button to add a new connection.
3. Select the Team connection type, and click Create.
4. On the Team tab:
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a. Optional: Set the name of the team interface in the Interface name field.
b. Click the Add button to add a new connection profile for a network interface and adding the
profile as a port to the team.
i. Select the connection type of the interface. For example, select Ethernet for a wired
connection.
ii. Optional: Set a connection name for the port.
iii. If you create a connection profile for an Ethernet device, open the Ethernet tab, and
select in the Device field the network interface you want to add as a port to the team. If
you selected a different device type, configure it accordingly. Note that you can only
use Ethernet interfaces in a team that are not assigned to any connection.
iv. Click Save.
c. Repeat the previous step for each interface you want to add to the team.
d. Click the Advanced button to set advanced options to the team connection.
i. On the Runner tab, select the runner.
ii. On the Link Watcher tab, set the link watcher and its optional settings.
iii. Click OK.
5. Configure the IP address settings on both the IPv4 Settings and IPv6 Settings tabs:
To use this bridge device as a port of other devices, set the Method field to Disabled.
To use DHCP, leave the Method field at its default, Automatic (DHCP).
To use static IP settings, set the Method field to Manual and fill the fields accordingly:
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6. Click Save.
7. Close nm-connection-editor.
Verification
Display the status of the team:
# teamdctl team0 state
setup:
runner: activebackup
ports:
enp7s0
link watches:
link summary: up
instance[link_watch_0]:
name: ethtool
link: up
down count: 0
enp8s0
link watches:
link summary: up
instance[link_watch_0]:
name: ethtool
link: up
down count: 0
runner:
active port: enp7s0
Additional resources
Configuring a network bond by using nm-connection-editor
Configuring a NIC team by using nm-connection-editor
Configuring VLAN tagging by using nm-connection-editor
Configuring NetworkManager to avoid using a specific profile to provide a default gateway
Understanding the teamd service, runners, and link-watchers
NetworkManager duplicates a connection after restart of NetworkManager service
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CHAPTER 5. CONFIGURING VLAN TAGGING
A Virtual Local Area Network (VLAN) is a logical network within a physical network. The VLAN interface
tags packets with the VLAN ID as they pass through the interface, and removes tags of returning
packets. You create VLAN interfaces on top of another interface, such as Ethernet, bond, team, or
bridge devices. These interfaces are called the parent interface.
Red Hat Enterprise Linux provides administrators different options to configure VLAN devices. For
example:
Use nmcli to configure VLAN tagging using the command line.
Use the RHEL web console to configure VLAN tagging using a web browser.
Use nmtui to configure VLAN tagging in a text-based user interface.
Use the nm-connection-editor application to configure connections in a graphical interface.
Use nmstatectl to configure connections through the Nmstate API.
Use RHEL system roles to automate the VLAN configuration on one or multiple hosts.
5.1. CONFIGURING VLAN TAGGING BY USING NMCLI
You can configure Virtual Local Area Network (VLAN) tagging on the command line using the nmcli
utility.
Prerequisites
The interface you plan to use as a parent to the virtual VLAN interface supports VLAN tags.
If you configure the VLAN on top of a bond interface:
The ports of the bond are up.
The bond is not configured with the fail_over_mac=follow option. A VLAN virtual device
cannot change its MAC address to match the parent’s new MAC address. In such a case, the
traffic would still be sent with the incorrect source MAC address.
The bond is usually not expected to get IP addresses from a DHCP server or IPv6 auto-
configuration. Ensure it by setting the ipv4.method=disable and ipv6.method=ignore
options while creating the bond. Otherwise, if DHCP or IPv6 auto-configuration fails after
some time, the interface might be brought down.
The switch, the host is connected to, is configured to support VLAN tags. For details, see the
documentation of your switch.
Procedure
1. Display the network interfaces:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp1s0 ethernet disconnected enp1s0
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89
bridge0 bridge connected bridge0
bond0 bond connected bond0
...
2. Create the VLAN interface. For example, to create a VLAN interface named vlan10 that uses
enp1s0 as its parent interface and that tags packets with VLAN ID 10, enter:
# nmcli connection add type vlan con-name vlan10 ifname vlan10 vlan.parent enp1s0
vlan.id 10
Note that the VLAN must be within the range from 0 to 4094.
3. By default, the VLAN connection inherits the maximum transmission unit (MTU) from the parent
interface. Optionally, set a different MTU value:
# nmcli connection modify vlan10 ethernet.mtu 2000
4. Configure the IPv4 settings:
To use this VLAN device as a port of other devices, enter:
# nmcli connection modify vlan10 ipv4.method disabled
To use DHCP, no action is required.
To set a static IPv4 address, network mask, default gateway, and DNS server to the vlan10
connection, enter:
# nmcli connection modify vlan10 ipv4.addresses '192.0.2.1/24' ipv4.gateway
'192.0.2.254' ipv4.dns '192.0.2.253' ipv4.method manual
5. Configure the IPv6 settings:
To use this VLAN device as a port of other devices, enter:
# nmcli connection modify vlan10 ipv6.method disabled
To use stateless address autoconfiguration (SLAAC), no action is required.
To set a static IPv6 address, network mask, default gateway, and DNS server to the vlan10
connection, enter:
# nmcli connection modify vlan10 ipv6.addresses '2001:db8:1::1/32' ipv6.gateway
'2001:db8:1::fffe' ipv6.dns '2001:db8:1::fffd' ipv6.method manual
6. Activate the connection:
# nmcli connection up vlan10
Verification
Verify the settings:
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# ip -d addr show vlan10
4: vlan10@enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
state UP group default qlen 1000
link/ether 52:54:00:72:2f:6e brd ff:ff:ff:ff:ff:ff promiscuity 0
vlan protocol 802.1Q id 10 <REORDER_HDR> numtxqueues 1 numrxqueues 1
gso_max_size 65536 gso_max_segs 65535
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute vlan10
valid_lft forever preferred_lft forever
inet6 2001:db8:1::1/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::8dd7:9030:6f8e:89e6/64 scope link noprefixroute
valid_lft forever preferred_lft forever
Additional resources
nm-settings(5) man page
5.2. CONFIGURING NESTED VLANS BY USING NMCLI
802.1ad is a protocol used for Virtual Local Area Network (VLAN) tagging. It is also known as Q-in-Q
tagging. You can use this technology to create multiple VLAN tags within a single Ethernet frame to
achieve the following benefits:
Increased network scalability by creating multiple isolated network segments within a VLAN. This
enables you to segment and organize large networks into smaller, manageable units.
Improved traffic management by isolating and controlling different types of network traffic.
This can improve the network performance and reduce network congestion.
Efficient resource utilization by enabling the creation of smaller, more targeted network
segments.
Enhanced security by isolating network traffic and reducing the risk of unauthorized access to
sensitive data.
Prerequisites
The interface you plan to use as a parent to the virtual VLAN interface supports VLAN tags.
If you configure the VLAN on top of a bond interface:
The ports of the bond are up.
The bond is not configured with the fail_over_mac=follow option. A VLAN virtual device
cannot change its MAC address to match the parent’s new MAC address. In such a case, the
traffic would still be sent with the incorrect source MAC address.
The bond is usually not expected to get IP addresses from a DHCP server or IPv6 auto-
configuration. Ensure it by setting the ipv4.method=disable and ipv6.method=ignore
options while creating the bond. Otherwise, if DHCP or IPv6 auto-configuration fails after
some time, the interface might be brought down.
The switch, the host is connected to, is configured to support VLAN tags. For details, see the
documentation of your switch.
Procedure
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91
Procedure
1. Display the physical network devices:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp1s0 ethernet connected enp1s0
...
2. Create the base VLAN interface. For example, to create a base VLAN interface named vlan10
that uses enp1s0 as its parent interface and that tags packets with VLAN ID 10, enter:
# nmcli connection add type vlan con-name vlan10 dev enp1s0 vlan.id 10
Note that the VLAN must be within the range from 0 to 4094.
3. By default, the VLAN connection inherits the maximum transmission unit (MTU) from the parent
interface. Optionally, set a different MTU value:
# nmcli connection modify vlan10 ethernet.mtu 2000
4. Create the nested VLAN interface on top of the base VLAN interface:
# nmcli connection add type vlan con-name vlan10.20 dev enp1s0.10 id 20
vlan.protocol 802.1ad
This command creates a new VLAN connection with a name of vlan10.20 and a VLAN ID of 20
on the parent VLAN connection vlan10. The dev option specifies the parent network device. In
this case it is enp1s0.10. The vlan.protocol option specifies the VLAN encapsulation protocol.
In this case it is 802.1ad (Q-in-Q).
5. Configure the IPv4 settings of the nested VLAN interface:
To use DHCP, no action is required.
To set a static IPv4 address, network mask, default gateway, and DNS server to the
vlan10.20 connection, enter:
# nmcli connection modify vlan10.20 ipv4.method manual ipv4.addresses
192.0.2.1/24 ipv4.gateway 192.0.2.254 ipv4.dns 192.0.2.200
6. Configure the IPv6 settings of the nested VLAN interface:
To use stateless address autoconfiguration (SLAAC), no action is required.
To set a static IPv4 address, network mask, default gateway, and DNS server to the vlan10
connection, enter:
# nmcli connection modify vlan10 ipv4.addresses '192.0.2.1/24' ipv4.gateway
'192.0.2.254' ipv4.dns '192.0.2.253' ipv4.method manual
7. Activate the profile:
# nmcli connection up vlan10.20
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Verification
1. Verify the configuration of the nested VLAN interface:
# ip -d addr show enp1s0.10.20
10: enp1s0.10.20@enp1s0.10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500
qdisc noqueue state UP group default qlen 1000
link/ether 52:54:00:d2:74:3e brd ff:ff:ff:ff:ff:ff promiscuity 0 minmtu 0 maxmtu 65535
vlan protocol 802.1ad id 20 <REORDER_HDR> numtxqueues 1 numrxqueues 1
gso_max_size 65536 gso_max_segs 65535 tso_max_size 65536 tso_max_segs 65535
gro_max_size 65536
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute enp1s0.10.20
valid_lft forever preferred_lft forever
inet6 2001:db8:1::1/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::ce3b:84c5:9ef8:d0e6/64 scope link noprefixroute
valid_lft forever preferred_lft forever
Additional resources
nm-settings(5) man page
5.3. CONFIGURING VLAN TAGGING BY USING THE RHEL WEB
CONSOLE
You can configure VLAN tagging if you prefer to manage network settings using a web browser-based
interface in the RHEL web console.
Prerequisites
The interface you plan to use as a parent to the virtual VLAN interface supports VLAN tags.
If you configure the VLAN on top of a bond interface:
The ports of the bond are up.
The bond is not configured with the fail_over_mac=follow option. A VLAN virtual device
cannot change its MAC address to match the parent’s new MAC address. In such a case, the
traffic would still be sent with the incorrect source MAC address.
The bond is usually not expected to get IP addresses from a DHCP server or IPv6 auto-
configuration. Ensure it by disabling the IPv4 and IPv6 protocol creating the bond.
Otherwise, if DHCP or IPv6 auto-configuration fails after some time, the interface might be
brought down.
The switch, the host is connected to, is configured to support VLAN tags. For details, see the
documentation of your switch.
You have installed the RHEL 9 web console.
For instructions, see Installing and enabling the web console .
Procedure
1. Log in to the RHEL 9 web console.
For details, see Logging in to the web console .
CHAPTER 5. CONFIGURING VLAN TAGGING
93
2. Select the Networking tab in the navigation on the left side of the screen.
3. Click Add VLAN in the Interfaces section.
4. Select the parent device.
5. Enter the VLAN ID.
6. Enter the name of the VLAN device or keep the automatically-generated name.
7. Click Apply.
8. By default, the VLAN device uses a dynamic IP address. If you want to set a static IP address:
a. Click the name of the VLAN device in the Interfaces section.
b. Click Edit next to the protocol you want to configure.
c. Select Manual next to Addresses, and enter the IP address, prefix, and default gateway.
d. In the DNS section, click the + button, and enter the IP address of the DNS server. Repeat
this step to set multiple DNS servers.
e. In the DNS search domains section, click the + button, and enter the search domain.
f. If the interface requires static routes, configure them in the Routes section.
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94
g. Click Apply
Verification
Select the Networking tab in the navigation on the left side of the screen, and check if there is
incoming and outgoing traffic on the interface:
5.4. CONFIGURING VLAN TAGGING BY USING NMTUI
The nmtui application provides a text-based user interface for NetworkManager. You can use nmtui to
configure VLAN tagging on a host without a graphical interface.
NOTE
CHAPTER 5. CONFIGURING VLAN TAGGING
95
NOTE
In nmtui:
Navigate by using the cursor keys.
Press a button by selecting it and hitting Enter.
Select and clear checkboxes by using Space.
Prerequisites
The interface you plan to use as a parent to the virtual VLAN interface supports VLAN tags.
If you configure the VLAN on top of a bond interface:
The ports of the bond are up.
The bond is not configured with the fail_over_mac=follow option. A VLAN virtual device
cannot change its MAC address to match the parent’s new MAC address. In such a case, the
traffic would still be sent with the then incorrect source MAC address.
The bond is usually not expected to get IP addresses from a DHCP server or IPv6 auto-
configuration. Ensure it by setting the ipv4.method=disable and ipv6.method=ignore
options while creating the bond. Otherwise, if DHCP or IPv6 auto-configuration fails after
some time, the interface might be brought down.
The switch the host is connected to is configured to support VLAN tags. For details, see the
documentation of your switch.
Procedure
1. If you do not know the network device name on which you want configure VLAN tagging, display
the available devices:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp1s0 ethernet unavailable --
...
2. Start nmtui:
# nmtui
3. Select Edit a connection, and press Enter.
4. Press Add.
5. Select VLAN from the list of network types, and press Enter.
6. Optional: Enter a name for the NetworkManager profile to be created.
On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a
profile.
7. Enter the VLAN device name to be created into the Device field.
8. Enter the name of the device on which you want to configure VLAN tagging into the Parent
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8. Enter the name of the device on which you want to configure VLAN tagging into the Parent
field.
9. Enter the VLAN ID. The ID must be within the range from 0 to 4094.
10. Depending on your environment, configure the IP address settings in the IPv4 configuration
and IPv6 configuration areas accordingly. For this, press the button next to these areas, and
select:
Disabled, if this VLAN device does not require an IP address or you want to use it as a port
of other devices.
Automatic, if a DHCP server or stateless address autoconfiguration (SLAAC) dynamically
assigns an IP address to the VLAN device.
Manual, if the network requires static IP address settings. In this case, you must fill further
fields:
i. Press Show next to the protocol you want to configure to display additional fields.
ii. Press Add next to Addresses, and enter the IP address and the subnet mask in
Classless Inter-Domain Routing (CIDR) format.
If you do not specify a subnet mask, NetworkManager sets a /32 subnet mask for IPv4
addresses and /64 for IPv6 addresses.
iii. Enter the address of the default gateway.
iv. Press Add next to DNS servers, and enter the DNS server address.
v. Press Add next to Search domains, and enter the DNS search domain.
Figure 5.1. Example of a VLAN connection with static IP address settings
CHAPTER 5. CONFIGURING VLAN TAGGING
97
Figure 5.1. Example of a VLAN connection with static IP address settings
11. Press OK to create and automatically activate the new connection.
12. Press Back to return to the main menu.
13. Select Quit, and press Enter to close the nmtui application.
Verification
Verify the settings:
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# ip -d addr show vlan10
4: vlan10@enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
state UP group default qlen 1000
link/ether 52:54:00:72:2f:6e brd ff:ff:ff:ff:ff:ff promiscuity 0
vlan protocol 802.1Q id 10 <REORDER_HDR> numtxqueues 1 numrxqueues 1
gso_max_size 65536 gso_max_segs 65535
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute vlan10
valid_lft forever preferred_lft forever
inet6 2001:db8:1::1/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::8dd7:9030:6f8e:89e6/64 scope link noprefixroute
valid_lft forever preferred_lft forever
5.5. CONFIGURING VLAN TAGGING BY USING NM-CONNECTION-
EDITOR
You can configure Virtual Local Area Network (VLAN) tagging in a graphical interface using the nm-
connection-editor application.
Prerequisites
The interface you plan to use as a parent to the virtual VLAN interface supports VLAN tags.
If you configure the VLAN on top of a bond interface:
The ports of the bond are up.
The bond is not configured with the fail_over_mac=follow option. A VLAN virtual device
cannot change its MAC address to match the parent’s new MAC address. In such a case, the
traffic would still be sent with the incorrect source MAC address.
The switch, the host is connected, to is configured to support VLAN tags. For details, see the
documentation of your switch.
Procedure
1. Open a terminal, and enter nm-connection-editor:
$ nm-connection-editor
2. Click the + button to add a new connection.
3. Select the VLAN connection type, and click Create.
4. On the VLAN tab:
a. Select the parent interface.
b. Select the VLAN id. Note that the VLAN must be within the range from 0 to 4094.
c. By default, the VLAN connection inherits the maximum transmission unit (MTU) from the
parent interface. Optionally, set a different MTU value.
d. Optional: Set the name of the VLAN interface and further VLAN-specific options.
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5. Configure the IP address settings on both the IPv4 Settings and IPv6 Settings tabs:
To use this bridge device as a port of other devices, set the Method field to Disabled.
To use DHCP, leave the Method field at its default, Automatic (DHCP).
To use static IP settings, set the Method field to Manual and fill the fields accordingly:
6. Click Save.
7. Close nm-connection-editor.
Verification
1. Verify the settings:
# ip -d addr show vlan10
4: vlan10@enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
state UP group default qlen 1000
link/ether 52:54:00:d5:e0:fb brd ff:ff:ff:ff:ff:ff promiscuity 0
vlan protocol 802.1Q id 10 <REORDER_HDR> numtxqueues 1 numrxqueues 1
gso_max_size 65536 gso_max_segs 65535
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute vlan10
valid_lft forever preferred_lft forever
inet6 2001:db8:1::1/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::8dd7:9030:6f8e:89e6/64 scope link noprefixroute
valid_lft forever preferred_lft forever
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Additional resources
Configuring NetworkManager to avoid using a specific profile to provide a default gateway
5.6. CONFIGURING VLAN TAGGING BY USING NMSTATECTL
Use the nmstatectl utility to configure Virtual Local Area Network VLAN through the Nmstate API. The
Nmstate API ensures that, after setting the configuration, the result matches the configuration file. If
anything fails, nmstatectl automatically rolls back the changes to avoid leaving the system in an
incorrect state.
Depending on your environment, adjust the YAML file accordingly. For example, to use different devices
than Ethernet adapters in the VLAN, adapt the base-iface attribute and type attributes of the ports you
use in the VLAN.
Prerequisites
To use Ethernet devices as ports in the VLAN, the physical or virtual Ethernet devices must be
installed on the server.
The nmstate package is installed.
Procedure
1. Create a YAML file, for example ~/create-vlan.yml, with the following content:
---
interfaces:
- name: vlan10
type: vlan
state: up
ipv4:
enabled: true
address:
- ip: 192.0.2.1
prefix-length: 24
dhcp: false
ipv6:
enabled: true
address:
- ip: 2001:db8:1::1
prefix-length: 64
autoconf: false
dhcp: false
vlan:
base-iface: enp1s0
id: 10
- name: enp1s0
type: ethernet
state: up
routes:
config:
- destination: 0.0.0.0/0
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These settings define a VLAN with ID 10 that uses the enp1s0 device. As the child device, the
VLAN connection has the following settings:
A static IPv4 address - 192.0.2.1 with the /24 subnet mask
A static IPv6 address - 2001:db8:1::1 with the /64 subnet mask
An IPv4 default gateway - 192.0.2.254
An IPv6 default gateway - 2001:db8:1::fffe
An IPv4 DNS server - 192.0.2.200
An IPv6 DNS server - 2001:db8:1::ffbb
A DNS search domain - example.com
2. Apply the settings to the system:
# nmstatectl apply ~/create-vlan.yml
Verification
1. Display the status of the devices and connections:
# nmcli device status
DEVICE TYPE STATE CONNECTION
vlan10 vlan connected vlan10
2. Display all settings of the connection profile:
# nmcli connection show vlan10
connection.id: vlan10
connection.uuid: 1722970f-788e-4f81-bd7d-a86bf21c9df5
connection.stable-id: --
connection.type: vlan
connection.interface-name: vlan10
...
3. Display the connection settings in YAML format:
next-hop-address: 192.0.2.254
next-hop-interface: vlan10
- destination: ::/0
next-hop-address: 2001:db8:1::fffe
next-hop-interface: vlan10
dns-resolver:
config:
search:
- example.com
server:
- 192.0.2.200
- 2001:db8:1::ffbb
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# nmstatectl show vlan0
Additional resources
nmstatectl(8) man page
/usr/share/doc/nmstate/examples/ directory
5.7. CONFIGURING VLAN TAGGING BY USING THE NETWORK
RHEL SYSTEM ROLE
If your network uses Virtual Local Area Networks (VLANs) to separate network traffic into logical
networks, create a NetworkManager connection profile to configure VLAN tagging. By using Ansible and
the network RHEL system role, you can automate this process and remotely configure connection
profiles on the hosts defined in a playbook.
You can use the network RHEL system role to configure VLAN tagging and, if a connection profile for
the VLAN’s parent device does not exists, the role can create it as well.
NOTE
If the VLAN device requires an IP address, default gateway, and DNS settings, configure
them on the VLAN device and not on the parent device.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
---
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: VLAN connection profile with Ethernet port
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
# Ethernet profile
- name: enp1s0
type: ethernet
interface_name: enp1s0
autoconnect: yes
state: up
ip:
dhcp4: no
auto6: no
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e settings specified in the example playbook include the following:
type: <profile_type>
Sets the type of the profile to create. The example playbook creates two connection
profiles: One for the parent Ethernet device and one for the VLAN device.
dhcp4: <value>
If set to yes, automatic IPv4 address assignment from DHCP, PPP, or similar services is
enabled. Disable the IP address configuration on the parent device.
auto6: <value>
If set to yes, IPv6 auto-configuration is enabled. In this case, by default, NetworkManager
uses Router Advertisements and, if the router announces the managed flag,
NetworkManager requests an IPv6 address and prefix from a DHCPv6 server. Disable the IP
address configuration on the parent device.
parent: <parent_device>
Sets the parent device of the VLAN connection profile. In the example, the parent is the
Ethernet interface.
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
Verify the VLAN settings:
# ansible managed-node-01.example.com -m command -a 'ip -d addr show enp1s0.10'
managed-node-01.example.com | CHANGED | rc=0 >>
4: vlan10@enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue
state UP group default qlen 1000
link/ether 52:54:00:72:2f:6e brd ff:ff:ff:ff:ff:ff promiscuity 0
# VLAN profile
- name: enp1s0.10
type: vlan
vlan:
id: 10
ip:
dhcp4: yes
auto6: yes
parent: enp1s0
state: up
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vlan protocol 802.1Q id 10 <REORDER_HDR> numtxqueues 1 numrxqueues 1
gso_max_size 65536 gso_max_segs 65535
...
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
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CHAPTER 6. CONFIGURING A NETWORK BRIDGE
A network bridge is a link-layer device which forwards traffic between networks based on a table of MAC
addresses. The bridge builds the MAC addresses table by listening to network traffic and thereby
learning what hosts are connected to each network. For example, you can use a software bridge on a
Red Hat Enterprise Linux host to emulate a hardware bridge or in virtualization environments, to
integrate virtual machines (VM) to the same network as the host.
A bridge requires a network device in each network the bridge should connect. When you configure a
bridge, the bridge is called controller and the devices it uses ports.
You can create bridges on different types of devices, such as:
Physical and virtual Ethernet devices
Network bonds
Network teams
VLAN devices
Due to the IEEE 802.11 standard which specifies the use of 3-address frames in Wi-Fi for the efficient
use of airtime, you cannot configure a bridge over Wi-Fi networks operating in Ad-Hoc or Infrastructure
modes.
6.1. CONFIGURING A NETWORK BRIDGE BY USING NMCLI
To configure a network bridge on the command line, use the nmcli utility.
Prerequisites
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports of the bridge, the physical or virtual Ethernet devices must be
installed on the server.
To use team, bond, or VLAN devices as ports of the bridge, you can either create these devices
while you create the bridge or you can create them in advance as described in:
Configuring a network team by using nmcli
Configuring a network bond by using nmcli
Configuring VLAN tagging by using nmcli
Procedure
1. Create a bridge interface:
# nmcli connection add type bridge con-name bridge0 ifname bridge0
This command creates a bridge named bridge0, enter:
2. Display the network interfaces, and note the names of the interfaces you want to add to the
bridge:
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# nmcli device status
DEVICE TYPE STATE CONNECTION
enp7s0 ethernet disconnected --
enp8s0 ethernet disconnected --
bond0 bond connected bond0
bond1 bond connected bond1
...
In this example:
enp7s0 and enp8s0 are not configured. To use these devices as ports, add connection
profiles in the next step.
bond0 and bond1 have existing connection profiles. To use these devices as ports, modify
their profiles in the next step.
3. Assign the interfaces to the bridge.
a. If the interfaces you want to assign to the bridge are not configured, create new connection
profiles for them:
# nmcli connection add type ethernet port-type bridge con-name bridge0-port1
ifname enp7s0 controller bridge0
# nmcli connection add type ethernet port-type bridge con-name bridge0-port2
ifname enp8s0 controller bridge0
These commands create profiles for enp7s0 and enp8s0, and add them to the bridge0
connection.
b. If you want to assign an existing connection profile to the bridge:
i. Set the controller parameter of these connections to bridge0:
# nmcli connection modify bond0 controller bridge0
# nmcli connection modify bond1 controller bridge0
These commands assign the existing connection profiles named bond0 and bond1 to
the bridge0 connection.
ii. Reactivate the connections:
# nmcli connection up bond0
# nmcli connection up bond1
4. Configure the IPv4 settings:
To use this bridge device as a port of other devices, enter:
# nmcli connection modify bridge0 ipv4.method disabled
To use DHCP, no action is required.
To set a static IPv4 address, network mask, default gateway, and DNS server to the bridge0
connection, enter:
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# nmcli connection modify bridge0 ipv4.addresses '192.0.2.1/24' ipv4.gateway
'192.0.2.254' ipv4.dns '192.0.2.253' ipv4.dns-search 'example.com' ipv4.method
manual
5. Configure the IPv6 settings:
To use this bridge device as a port of other devices, enter:
# nmcli connection modify bridge0 ipv6.method disabled
To use stateless address autoconfiguration (SLAAC), no action is required.
To set a static IPv6 address, network mask, default gateway, and DNS server to the bridge0
connection, enter:
# nmcli connection modify bridge0 ipv6.addresses '2001:db8:1::1/64' ipv6.gateway
'2001:db8:1::fffe' ipv6.dns '2001:db8:1::fffd' ipv6.dns-search 'example.com'
ipv6.method manual
6. Optional: Configure further properties of the bridge. For example, to set the Spanning Tree
Protocol (STP) priority of bridge0 to 16384, enter:
# nmcli connection modify bridge0 bridge.priority '16384'
By default, STP is enabled.
7. Activate the connection:
# nmcli connection up bridge0
8. Verify that the ports are connected, and the CONNECTION column displays the port’s
connection name:
# nmcli device
DEVICE TYPE STATE CONNECTION
...
enp7s0 ethernet connected bridge0-port1
enp8s0 ethernet connected bridge0-port2
When you activate any port of the connection, NetworkManager also activates the bridge, but
not the other ports of it. You can configure that Red Hat Enterprise Linux enables all ports
automatically when the bridge is enabled:
a. Enable the connection.autoconnect-ports parameter of the bridge connection:
# nmcli connection modify bridge0 connection.autoconnect-ports 1
b. Reactivate the bridge:
# nmcli connection up bridge0
Verification
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Use the ip utility to display the link status of Ethernet devices that are ports of a specific bridge:
# ip link show master bridge0
3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master
bridge0 state UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:62:61:0e brd ff:ff:ff:ff:ff:ff
4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master
bridge0 state UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:9e:f1:ce brd ff:ff:ff:ff:ff:ff
Use the bridge utility to display the status of Ethernet devices that are ports of any bridge
device:
# bridge link show
3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state
forwarding priority 32 cost 100
4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state
listening priority 32 cost 100
5: enp9s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge1 state
forwarding priority 32 cost 100
6: enp11s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge1 state
blocking priority 32 cost 100
...
To display the status for a specific Ethernet device, use the bridge link show dev
<ethernet_device_name> command.
Additional resources
nm-settings(5) man page
bridge(8) man page
NetworkManager duplicates a connection after restart of NetworkManager service
How to configure a bridge with VLAN information?
6.2. CONFIGURING A NETWORK BRIDGE BY USING THE RHEL WEB
CONSOLE
Use the RHEL web console to configure a network bridge if you prefer to manage network settings using
a web browser-based interface.
Prerequisites
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports of the bridge, the physical or virtual Ethernet devices must be
installed on the server.
To use team, bond, or VLAN devices as ports of the bridge, you can either create these devices
while you create the bridge or you can create them in advance as described in:
Configuring a network team using the RHEL web console
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Configuring a network bond by using the RHEL web console
Configuring VLAN tagging by using the RHEL web console
You have installed the RHEL 9 web console.
For instructions, see Installing and enabling the web console .
Procedure
1. Log in to the RHEL 9 web console.
For details, see Logging in to the web console .
2. Select the Networking tab in the navigation on the left side of the screen.
3. Click Add bridge in the Interfaces section.
4. Enter the name of the bridge device you want to create.
5. Select the interfaces that should be ports of the bridge.
6. Optional: Enable the Spanning tree protocol (STP) feature to avoid bridge loops and
broadcast radiation.
7. Click Apply.
8. By default, the bridge uses a dynamic IP address. If you want to set a static IP address:
a. Click the name of the bridge in the Interfaces section.
b. Click Edit next to the protocol you want to configure.
c. Select Manual next to Addresses, and enter the IP address, prefix, and default gateway.
d. In the DNS section, click the + button, and enter the IP address of the DNS server. Repeat
this step to set multiple DNS servers.
e. In the DNS search domains section, click the + button, and enter the search domain.
f. If the interface requires static routes, configure them in the Routes section.
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g. Click Apply
Verification
1. Select the Networking tab in the navigation on the left side of the screen, and check if there is
incoming and outgoing traffic on the interface:
6.3. CONFIGURING A NETWORK BRIDGE BY USING NMTUI
The nmtui application provides a text-based user interface for NetworkManager. You can use nmtui to
configure a network bridge on a host without a graphical interface.
NOTE
CHAPTER 6. CONFIGURING A NETWORK BRIDGE
111
NOTE
In nmtui:
Navigate by using the cursor keys.
Press a button by selecting it and hitting Enter.
Select and clear checkboxes by using Space.
Prerequisites
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports of the bridge, the physical or virtual Ethernet devices must be
installed on the server.
Procedure
1. If you do not know the network device names on which you want configure a network bridge,
display the available devices:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp7s0 ethernet unavailable --
enp8s0 ethernet unavailable --
...
2. Start nmtui:
# nmtui
3. Select Edit a connection, and press Enter.
4. Press Add.
5. Select Bridge from the list of network types, and press Enter.
6. Optional: Enter a name for the NetworkManager profile to be created.
On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a
profile.
7. Enter the bridge device name to be created into the Device field.
8. Add ports to the bridge to be created:
a. Press Add next to the Slaves list.
b. Select the type of the interface you want to add as port to the bridge, for example,
Ethernet.
c. Optional: Enter a name for the NetworkManager profile to be created for this bridge port.
d. Enter the port’s device name into the Device field.
e. Press OK to return to the window with the bridge settings.
Figure 6.1. Adding an Ethernet device as port to a bridge
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Figure 6.1. Adding an Ethernet device as port to a bridge
f. Repeat these steps to add more ports to the bridge.
9. Depending on your environment, configure the IP address settings in the IPv4 configuration
and IPv6 configuration areas accordingly. For this, press the button next to these areas, and
select:
Disabled, if the bridge does not require an IP address.
Automatic, if a DHCP server or stateless address autoconfiguration (SLAAC) dynamically
assigns an IP address to the bridge.
Manual, if the network requires static IP address settings. In this case, you must fill further
fields:
i. Press Show next to the protocol you want to configure to display additional fields.
ii. Press Add next to Addresses, and enter the IP address and the subnet mask in
Classless Inter-Domain Routing (CIDR) format.
If you do not specify a subnet mask, NetworkManager sets a /32 subnet mask for IPv4
addresses and /64 for IPv6 addresses.
iii. Enter the address of the default gateway.
iv. Press Add next to DNS servers, and enter the DNS server address.
v. Press Add next to Search domains, and enter the DNS search domain.
Figure 6.2. Example of a bridge connection without IP address settings
CHAPTER 6. CONFIGURING A NETWORK BRIDGE
113
Figure 6.2. Example of a bridge connection without IP address settings
10. Press OK to create and automatically activate the new connection.
11. Press Back to return to the main menu.
12. Select Quit, and press Enter to close the nmtui application.
Verification
1. Use the ip utility to display the link status of Ethernet devices that are ports of a specific bridge:
# ip link show master bridge0
3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master
bridge0 state UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:62:61:0e brd ff:ff:ff:ff:ff:ff
4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master
bridge0 state UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:9e:f1:ce brd ff:ff:ff:ff:ff:ff
2. Use the bridge utility to display the status of Ethernet devices that are ports of any bridge
device:
# bridge link show
3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state
forwarding priority 32 cost 100
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4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state
listening priority 32 cost 100
...
To display the status for a specific Ethernet device, use the bridge link show dev
<ethernet_device_name> command.
6.4. CONFIGURING A NETWORK BRIDGE BY USING NM-
CONNECTION-EDITOR
If you use Red Hat Enterprise Linux with a graphical interface, you can configure network bridges using
the nm-connection-editor application.
Note that nm-connection-editor can add only new ports to a bridge. To use an existing connection
profile as a port, create the bridge using the nmcli utility as described in Configuring a network bridge by
using nmcli.
Prerequisites
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports of the bridge, the physical or virtual Ethernet devices must be
installed on the server.
To use team, bond, or VLAN devices as ports of the bridge, ensure that these devices are not
already configured.
Procedure
1. Open a terminal, and enter nm-connection-editor:
$ nm-connection-editor
2. Click the + button to add a new connection.
3. Select the Bridge connection type, and click Create.
4. On the Bridge tab:
a. Optional: Set the name of the bridge interface in the Interface name field.
b. Click the Add button to create a new connection profile for a network interface and adding
the profile as a port to the bridge.
i. Select the connection type of the interface. For example, select Ethernet for a wired
connection.
ii. Optional: Set a connection name for the port device.
iii. If you create a connection profile for an Ethernet device, open the Ethernet tab, and
select in the Device field the network interface you want to add as a port to the bridge.
If you selected a different device type, configure it accordingly.
iv. Click Save.
CHAPTER 6. CONFIGURING A NETWORK BRIDGE
115
c. Repeat the previous step for each interface you want to add to the bridge.
5. Optional: Configure further bridge settings, such as Spanning Tree Protocol (STP) options.
6. Configure the IP address settings on both the IPv4 Settings and IPv6 Settings tabs:
To use this bridge device as a port of other devices, set the Method field to Disabled.
To use DHCP, leave the Method field at its default, Automatic (DHCP).
To use static IP settings, set the Method field to Manual and fill the fields accordingly:
7. Click Save.
8. Close nm-connection-editor.
Verification
Use the ip utility to display the link status of Ethernet devices that are ports of a specific bridge.
# ip link show master bridge0
3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master
bridge0 state UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:62:61:0e brd ff:ff:ff:ff:ff:ff
4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master
bridge0 state UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:9e:f1:ce brd ff:ff:ff:ff:ff:ff
Use the bridge utility to display the status of Ethernet devices that are ports in any bridge
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Use the bridge utility to display the status of Ethernet devices that are ports in any bridge
device:
# bridge link show
3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state
forwarding priority 32 cost 100
4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state
listening priority 32 cost 100
5: enp9s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge1 state
forwarding priority 32 cost 100
6: enp11s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge1 state
blocking priority 32 cost 100
...
To display the status for a specific Ethernet device, use the bridge link show dev
ethernet_device_name command.
Additional resources
Configuring a network bond by using nm-connection-editor
Configuring a network team by using nm-connection-editor
Configuring VLAN tagging by using nm-connection-editor
Configuring NetworkManager to avoid using a specific profile to provide a default gateway
How to configure a bridge with VLAN information?
6.5. CONFIGURING A NETWORK BRIDGE BY USING NMSTATECTL
Use the nmstatectl utility to configure a network bridge through the Nmstate API. The Nmstate API
ensures that, after setting the configuration, the result matches the configuration file. If anything fails,
nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.
Depending on your environment, adjust the YAML file accordingly. For example, to use different devices
than Ethernet adapters in the bridge, adapt the base-iface attribute and type attributes of the ports
you use in the bridge.
Prerequisites
Two or more physical or virtual network devices are installed on the server.
To use Ethernet devices as ports in the bridge, the physical or virtual Ethernet devices must be
installed on the server.
To use team, bond, or VLAN devices as ports in the bridge, set the interface name in the port
list, and define the corresponding interfaces.
The nmstate package is installed.
Procedure
1. Create a YAML file, for example ~/create-bridge.yml, with the following content:
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117
These settings define a network bridge with the following settings:
Network interfaces in the bridge: enp1s0 and enp7s0
Spanning Tree Protocol (STP): Enabled
Static IPv4 address: 192.0.2.1 with the /24 subnet mask
---
interfaces:
- name: bridge0
type: linux-bridge
state: up
ipv4:
enabled: true
address:
- ip: 192.0.2.1
prefix-length: 24
dhcp: false
ipv6:
enabled: true
address:
- ip: 2001:db8:1::1
prefix-length: 64
autoconf: false
dhcp: false
bridge:
options:
stp:
enabled: true
port:
- name: enp1s0
- name: enp7s0
- name: enp1s0
type: ethernet
state: up
- name: enp7s0
type: ethernet
state: up
routes:
config:
- destination: 0.0.0.0/0
next-hop-address: 192.0.2.254
next-hop-interface: bridge0
- destination: ::/0
next-hop-address: 2001:db8:1::fffe
next-hop-interface: bridge0
dns-resolver:
config:
search:
- example.com
server:
- 192.0.2.200
- 2001:db8:1::ffbb
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Static IPv6 address: 2001:db8:1::1 with the /64 subnet mask
IPv4 default gateway: 192.0.2.254
IPv6 default gateway: 2001:db8:1::fffe
IPv4 DNS server: 192.0.2.200
IPv6 DNS server: 2001:db8:1::ffbb
DNS search domain: example.com
2. Apply the settings to the system:
# nmstatectl apply ~/create-bridge.yml
Verification
1. Display the status of the devices and connections:
# nmcli device status
DEVICE TYPE STATE CONNECTION
bridge0 bridge connected bridge0
2. Display all settings of the connection profile:
# nmcli connection show bridge0
connection.id: bridge0_
connection.uuid: e2cc9206-75a2-4622-89cf-1252926060a9
connection.stable-id: --
connection.type: bridge
connection.interface-name: bridge0
...
3. Display the connection settings in YAML format:
# nmstatectl show bridge0
Additional resources
nmstatectl(8) man page
/usr/share/doc/nmstate/examples/ directory
How to configure a bridge with VLAN information?
6.6. CONFIGURING A NETWORK BRIDGE BY USING THE NETWORK
RHEL SYSTEM ROLE
You can connect multiple networks on layer 2 of the Open Systems Interconnection (OSI) model by
creating a network bridge. To configure a bridge, create a connection profile in NetworkManager. By
using Ansible and the network RHEL system role, you can automate this process and remotely
configure connection profiles on the hosts defined in a playbook.
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You can use the network RHEL system role to configure a bridge and, if a connection profile for the
bridge’s parent device does not exists, the role can create it as well.
NOTE
If you want to assign IP addresses, gateways, and DNS settings to a bridge, configure
them on the bridge and not on its ports.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
Two or more physical or virtual network devices are installed on the server.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
---
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: Bridge connection profile with two Ethernet ports
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
# Bridge profile
- name: bridge0
type: bridge
interface_name: bridge0
ip:
dhcp4: yes
auto6: yes
state: up
# Port profile for the 1st Ethernet device
- name: bridge0-port1
interface_name: enp7s0
type: ethernet
controller: bridge0
port_type: bridge
state: up
# Port profile for the 2nd Ethernet device
- name: bridge0-port2
interface_name: enp8s0
type: ethernet
controller: bridge0
port_type: bridge
state: up
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The settings specified in the example playbook include the following:
type: <profile_type>
Sets the type of the profile to create. The example playbook creates three connection
profiles: One for the bridge and two for the Ethernet devices.
dhcp4: yes
Enables automatic IPv4 address assignment from DHCP, PPP, or similar services.
auto6: yes
Enables IPv6 auto-configuration. By default, NetworkManager uses Router Advertisements.
If the router announces the managed flag, NetworkManager requests an IPv6 address and
prefix from a DHCPv6 server.
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
1. Display the link status of Ethernet devices that are ports of a specific bridge:
# ansible managed-node-01.example.com -m command -a 'ip link show master
bridge0'
managed-node-01.example.com | CHANGED | rc=0 >>
3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master
bridge0 state UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:62:61:0e brd ff:ff:ff:ff:ff:ff
4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master
bridge0 state UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:9e:f1:ce brd ff:ff:ff:ff:ff:ff
2. Display the status of Ethernet devices that are ports of any bridge device:
# ansible managed-node-01.example.com -m command -a 'bridge link show'
managed-node-01.example.com | CHANGED | rc=0 >>
3: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state
forwarding priority 32 cost 100
4: enp8s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 master bridge0 state
listening priority 32 cost 100
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
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/usr/share/doc/rhel-system-roles/network/ directory
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CHAPTER 7. SETTING UP AN IPSEC VPN
A virtual private network (VPN) is a way of connecting to a local network over the internet. IPsec
provided by Libreswan is the preferred method for creating a VPN. Libreswan is a user-space IPsec
implementation for VPN. A VPN enables the communication between your LAN, and another, remote
LAN by setting up a tunnel across an intermediate network such as the internet. For security reasons, a
VPN tunnel always uses authentication and encryption. For cryptographic operations, Libreswan uses
the NSS library.
7.1. CONFIGURING A VPN CONNECTION WITH CONTROL-CENTER
If you use Red Hat Enterprise Linux with a graphical interface, you can configure a VPN connection in
the GNOME control-center.
Prerequisites
The NetworkManager-libreswan-gnome package is installed.
Procedure
1. Press the Super key, type Settings, and press Enter to open the control-center application.
2. Select the Network entry on the left.
3. Click the + icon.
4. Select VPN.
5. Select the Identity menu entry to see the basic configuration options:
General
Gateway — The name or IP address of the remote VPN gateway.
Authentication
Type
IKEv2 (Certificate)- client is authenticated by certificate. It is more secure (default).
IKEv1 (XAUTH) - client is authenticated by user name and password, or a pre-shared key
(PSK).
The following configuration settings are available under the Advanced section:
Figure 7.1. Advanced options of a VPN connection
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Figure 7.1. Advanced options of a VPN connection
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WARNING
When configuring an IPsec-based VPN connection using the gnome-
control-center application, the Advanced dialog displays the
configuration, but it does not allow any changes. As a consequence,
users cannot change any advanced IPsec options. Use the nm-
connection-editor or nmcli tools instead to perform configuration of
the advanced properties.
Identification
Domain — If required, enter the Domain Name.
Security
Phase1 Algorithms — corresponds to the ike Libreswan parameter — enter the algorithms
to be used to authenticate and set up an encrypted channel.
Phase2 Algorithms — corresponds to the esp Libreswan parameter — enter the algorithms
to be used for the IPsec negotiations.
Check the Disable PFS field to turn off Perfect Forward Secrecy (PFS) to ensure
compatibility with old servers that do not support PFS.
Phase1 Lifetime — corresponds to the ikelifetime Libreswan parameter — how long the key
used to encrypt the traffic will be valid.
Phase2 Lifetime — corresponds to the salifetime Libreswan parameter — how long a
particular instance of a connection should last before expiring.
Note that the encryption key should be changed from time to time for security reasons.
Remote network — corresponds to the rightsubnet Libreswan parameter — the destination
private remote network that should be reached through the VPN.
Check the narrowing field to enable narrowing. Note that it is only effective in IKEv2
negotiation.
Enable fragmentation — corresponds to the fragmentation Libreswan parameter —
whether or not to allow IKE fragmentation. Valid values are yes (default) or no.
Enable Mobike — corresponds to the mobike Libreswan parameter — whether to allow
Mobility and Multihoming Protocol (MOBIKE, RFC 4555) to enable a connection to migrate
its endpoint without needing to restart the connection from scratch. This is used on mobile
devices that switch between wired, wireless, or mobile data connections. The values are no
(default) or yes.
6. Select the IPv4 menu entry:
IPv4 Method
Automatic (DHCP) — Choose this option if the network you are connecting to uses a DHCP
server to assign dynamic IP addresses.
Link-Local Only — Choose this option if the network you are connecting to does not have a
DHCP server and you do not want to assign IP addresses manually. Random addresses will
be assigned as per RFC 3927 with prefix 169.254/16.
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Manual — Choose this option if you want to assign IP addresses manually.
Disable — IPv4 is disabled for this connection.
DNS
In the DNS section, when Automatic is ON, switch it to OFF to enter the IP address of a
DNS server you want to use separating the IPs by comma.
Routes
Note that in the Routes section, when Automatic is ON, routes from DHCP are used, but
you can also add additional static routes. When OFF, only static routes are used.
Address — Enter the IP address of a remote network or host.
Netmask — The netmask or prefix length of the IP address entered above.
Gateway — The IP address of the gateway leading to the remote network or host entered
above.
Metric — A network cost, a preference value to give to this route. Lower values will be
preferred over higher values.
Use this connection only for resources on its network
Select this check box to prevent the connection from becoming the default route. Selecting
this option means that only traffic specifically destined for routes learned automatically over
the connection or entered here manually is routed over the connection.
7. To configure IPv6 settings in a VPN connection, select the IPv6 menu entry:
IPv6 Method
Automatic — Choose this option to use IPv6 Stateless Address AutoConfiguration
(SLAAC) to create an automatic, stateless configuration based on the hardware address
and Router Advertisements (RA).
Automatic, DHCP only — Choose this option to not use RA, but request information from
DHCPv6 directly to create a stateful configuration.
Link-Local Only — Choose this option if the network you are connecting to does not have a
DHCP server and you do not want to assign IP addresses manually. Random addresses will
be assigned as per RFC 4862 with prefix FE80::0.
Manual — Choose this option if you want to assign IP addresses manually.
Disable — IPv6 is disabled for this connection.
Note that DNS, Routes, Use this connection only for resources on its network are
common to IPv4 settings.
8. Once you have finished editing the VPN connection, click the Add button to customize the
configuration or the Apply button to save it for the existing one.
9. Switch the profile to ON to active the VPN connection.
Additional resources
nm-settings-libreswan(5)
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7.2. CONFIGURING A VPN CONNECTION USING NM-CONNECTION-
EDITOR
If you use Red Hat Enterprise Linux with a graphical interface, you can configure a VPN connection in
the nm-connection-editor application.
Prerequisites
The NetworkManager-libreswan-gnome package is installed.
If you configure an Internet Key Exchange version 2 (IKEv2) connection:
The certificate is imported into the IPsec network security services (NSS) database.
The nickname of the certificate in the NSS database is known.
Procedure
1. Open a terminal, and enter:
$ nm-connection-editor
2. Click the + button to add a new connection.
3. Select the IPsec based VPN connection type, and click Create.
4. On the VPN tab:
a. Enter the host name or IP address of the VPN gateway into the Gateway field, and select
an authentication type. Based on the authentication type, you must enter different
additional information:
IKEv2 (Certifiate) authenticates the client by using a certificate, which is more secure.
This setting requires the nickname of the certificate in the IPsec NSS database
IKEv1 (XAUTH) authenticates the user by using a user name and password (pre-shared
key). This setting requires that you enter the following values:
User name
Password
Group name
Secret
b. If the remote server specifies a local identifier for the IKE exchange, enter the exact string
in the Remote ID field. In the remote server runs Libreswan, this value is set in the server’s
leftid parameter.
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c. Optional: Configure additional settings by clicking the Advanced button. You can configure
the following settings:
Identification
Domain — If required, enter the domain name.
Security
Phase1 Algorithms corresponds to the ike Libreswan parameter. Enter the
algorithms to be used to authenticate and set up an encrypted channel.
Phase2 Algorithms corresponds to the esp Libreswan parameter. Enter the
algorithms to be used for the IPsec negotiations.
Check the Disable PFS field to turn off Perfect Forward Secrecy (PFS) to ensure
compatibility with old servers that do not support PFS.
Phase1 Lifetime corresponds to the ikelifetime Libreswan parameter. This
parameter defines how long the key used to encrypt the traffic is valid.
Phase2 Lifetime corresponds to the salifetime Libreswan parameter. This
parameter defines how long a security association is valid.
Connectivity
Remote network corresponds to the rightsubnet Libreswan parameter and
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Remote network corresponds to the rightsubnet Libreswan parameter and
defines the destination private remote network that should be reached through the
VPN.
Check the narrowing field to enable narrowing. Note that it is only effective in the
IKEv2 negotiation.
Enable fragmentation corresponds to the fragmentation Libreswan parameter
and defines whether or not to allow IKE fragmentation. Valid values are yes
(default) or no.
Enable Mobike corresponds to the mobike Libreswan parameter. The parameter
defines whether to allow Mobility and Multihoming Protocol (MOBIKE) (RFC 4555)
to enable a connection to migrate its endpoint without needing to restart the
connection from scratch. This is used on mobile devices that switch between wired,
wireless or mobile data connections. The values are no (default) or yes.
5. On the IPv4 Settings tab, select the IP assignment method and, optionally, set additional static
addresses, DNS servers, search domains, and routes.
6. Save the connection.
7. Close nm-connection-editor.
NOTE
When you add a new connection by clicking the + button, NetworkManager creates a new
configuration file for that connection and then opens the same dialog that is used for
editing an existing connection. The difference between these dialogs is that an existing
connection profile has a Details menu entry.
Additional resources
nm-settings-libreswan(5) man page
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7.3. CONFIGURING AUTOMATIC DETECTION AND USAGE OF ESP
HARDWARE OFFLOAD TO ACCELERATE AN IPSEC CONNECTION
Offloading Encapsulating Security Payload (ESP) to the hardware accelerates IPsec connections over
Ethernet. By default, Libreswan detects if hardware supports this feature and, as a result, enables ESP
hardware offload. In case that the feature was disabled or explicitly enabled, you can switch back to
automatic detection.
Prerequisites
The network card supports ESP hardware offload.
The network driver supports ESP hardware offload.
The IPsec connection is configured and works.
Procedure
1. Edit the Libreswan configuration file in the /etc/ipsec.d/ directory of the connection that should
use automatic detection of ESP hardware offload support.
2. Ensure the nic-offload parameter is not set in the connection’s settings.
3. If you removed nic-offload, restart the ipsec service:
# systemctl restart ipsec
Verification
1. Display the tx_ipsec and rx_ipsec counters of the Ethernet device the IPsec connection uses:
# ethtool -S enp1s0 | egrep "_ipsec"
tx_ipsec: 10
rx_ipsec: 10
2. Send traffic through the IPsec tunnel. For example, ping a remote IP address:
# ping -c 5 remote_ip_address
3. Display the tx_ipsec and rx_ipsec counters of the Ethernet device again:
# ethtool -S enp1s0 | egrep "_ipsec"
tx_ipsec: 15
rx_ipsec: 15
If the counter values have increased, ESP hardware offload works.
Additional resources
Configuring a VPN with IPsec
7.4. CONFIGURING ESP HARDWARE OFFLOAD ON A BOND TO
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7.4. CONFIGURING ESP HARDWARE OFFLOAD ON A BOND TO
ACCELERATE AN IPSEC CONNECTION
Offloading Encapsulating Security Payload (ESP) to the hardware accelerates IPsec connections. If you
use a network bond for fail-over reasons, the requirements and the procedure to configure ESP
hardware offload are different from those using a regular Ethernet device. For example, in this scenario,
you enable the offload support on the bond, and the kernel applies the settings to the ports of the bond.
Prerequisites
All network cards in the bond support ESP hardware offload.
The network driver supports ESP hardware offload on a bond device. In RHEL, only the ixgbe
driver supports this feature.
The bond is configured and works.
The bond uses the active-backup mode. The bonding driver does not support any other modes
for this feature.
The IPsec connection is configured and works.
Procedure
1. Enable ESP hardware offload support on the network bond:
# nmcli connection modify bond0 ethtool.feature-esp-hw-offload on
This command enables ESP hardware offload support on the bond0 connection.
2. Reactivate the bond0 connection:
# nmcli connection up bond0
3. Edit the Libreswan configuration file in the /etc/ipsec.d/ directory of the connection that should
use ESP hardware offload, and append the nic-offload=yes statement to the connection entry:
conn example
...
nic-offload=yes
4. Restart the ipsec service:
# systemctl restart ipsec
Verification
1. Display the active port of the bond:
# grep "Currently Active Slave" /proc/net/bonding/bond0
Currently Active Slave: enp1s0
2. Display the tx_ipsec and rx_ipsec counters of the active port:
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# ethtool -S enp1s0 | egrep "_ipsec"
tx_ipsec: 10
rx_ipsec: 10
3. Send traffic through the IPsec tunnel. For example, ping a remote IP address:
# ping -c 5 remote_ip_address
4. Display the tx_ipsec and rx_ipsec counters of the active port again:
# ethtool -S enp1s0 | egrep "_ipsec"
tx_ipsec: 15
rx_ipsec: 15
If the counter values have increased, ESP hardware offload works.
Additional resources
Configuring a network bond
Configuring a VPN with IPsec section in the Securing networks document
7.5. CONFIGURING AN IPSEC BASED VPN CONNECTION BY USING
NMSTATECTL
IPsec (Internet Protocol Security) is a security protocol suite, provided by Libreswan, for
implementation of VPN. IPsec includes protocols to initiate authentication at the time of connection
establishment and manage keys during the data transfer. When an application deploys in a network and
communicates by using the IP protocol, IPsec can protect data communication.
To manage an IPsec-based configuration for authenticating VPN connections, you can use the
nmstatectl utility. This utility provides command line access to a declarative API for host network
management. The following are the authentication types for the host-to-subnet and host-to-host
communication modes:
Host-to-subnet PKI authentication
Host-to-subnet RSA authentication
Host-to-subnet PSK authentication
Host-to-host tunnel mode authentication
Host-to-host transport mode authentication
7.5.1. Configuring a host-to-subnet IPSec VPN with PKI authentication and tunnel
mode by using nmstatectl
If you want to use encryption based on the trusted entity authentication in IPsec, Public Key
Infrastructure (PKI) provides secure communication by using cryptographic keys between two hosts.
Both communicating hosts generate private and public keys where each host maintains a private key by
sharing public key with the trusted entity Certificate Authority (CA). The CA generates a digital
certificate after verifying the authenticity. In case of encryption and decryption, the host uses a private
key for encryption and public key for decryption.
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By using Nmstate, a declarative API for network management, you can configure a PKI authentication-
based IPsec connection. After setting the configuration, the Nmstate API ensures that the result
matches with the configuration file. If anything fails, nmstate automatically rolls back the changes to
avoid an incorrect state of the system.
To establish encrypted communication in host-to-subnet configuration, remote IPsec end provides
another IP to host by using parameter dhcp: true. In the case of defining systems for IPsec in nmstate,
the left-named system is the local host while the right-named system is the remote host. The following
procedure needs to run on both hosts.
Prerequisites
By using a password, you have generated a PKCS #12 file that stores certificates and
cryptographic keys.
Procedure
1. Install the required packages:
# dnf install nmstate libreswan NetworkManager-libreswan
2. Restart the NetworkManager service:
# systemctl restart NetworkManager
3. As Libreswan was already installed, remove its old database files and re-create them:
# systemctl stop ipsec
# rm /etc/ipsec.d/*db
# ipsec initnss
4. Enable and start the ipsec service:
# systemctl enable --now ipsec
5. Import the PKCS#12 file:
# ipsec import node-example.p12
When importing the PKCS#12 file, enter the password that was used to create the file.
6. Create a YAML file, for example ~/create-pki-authentication.yml, with the following content:
---
interfaces:
- name: 'example_ipsec_conn1' 1
type: ipsec
ipv4:
enabled: true
dhcp: true
libreswan:
ipsec-interface: 'yes' 2
left: '192.0.2.250' 3
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1
2
3
4
5
6
7
8
9
10
The YAML file defines the following settings:
An IPsec connection name
The value yes means libreswan creates an IPsec xfrm virtual interface ipsec<number>
and automatically finds the next available number
A static IPv4 address of public network interface for a local host
On a local host, the value of %fromcert sets the ID to a Distinguished Name (DN) that is
fetched from a loaded certificate
A Distinguished Name (DN) of a local host’s public key
A static IPv4 address of public network interface for a remote host
On a remote host, the value of %fromcert sets the ID to a Distinguished Name (DN) that is
fetched from a loaded certificate.
insist value accepts and receives only the Internet Key Exchange (IKEv2) protocol
The duration of IKE protocol
The duration of IPsec security association (SA)
7. Apply settings to the system:
# nmstatectl apply ~/create-pki-authentication.yml
Verification
1. Verify IPsec status:
# ip xfrm status
2. Verify IPsec policies:
# ip xfrm policy
Additional resources
ipsec.conf(5) man page
7.5.2. Configuring a host-to-subnet IPSec VPN with RSA authentication and tunnel
leftid: '%fromcert' 4
leftcert: 'local-host.example.com' 5
right: '192.0.2.150' 6
rightid: '%fromcert' 7
ikev2: 'insist' 8
ikelifetime: '24h' 9
salifetime: '24h' 10
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7.5.2. Configuring a host-to-subnet IPSec VPN with RSA authentication and tunnel
mode by using nmstatectl
If you want to use asymmetric cryptography-based key authentication in IPsec, the RSA algorithm
provides secure communication by using either of private and public keys for encryption and decryption
between two hosts. This method uses a private key for encryption, and a public key for decryption.
By using Nmstate, a declarative API for network management, you can configure RSA-based IPsec
authentication. After setting the configuration, the Nmstate API ensures that the result matches with
the configuration file. If anything fails, nmstate automatically rolls back the changes to avoid an
incorrect state of the system.
To establish encrypted communication in host-to-subnet configuration, remote IPsec end provides
another IP to host by using parameter dhcp: true. In the case of defining systems for IPsec in nmstate,
the left-named system is the local host while the right-named system is the remote host. The following
procedure needs to run on both hosts.
Procedure
1. Install the required packages:
# dnf install nmstate libreswan NetworkManager-libreswan
2. Restart the NetworkManager service:
# systemctl restart NetworkManager
3. If Libreswan was already installed, remove its old database files and re-create them:
# systemctl stop ipsec
# rm /etc/ipsec.d/*db
# ipsec initnss
4. Generate a RSA key pair on each host:
# ipsec newhostkey --output
5. Display the public keys:
# ipsec showhostkey --list
6. The previous step returned the generated key ckaid. Use that ckaid with the following
command on left, for example:
# ipsec showhostkey --left --ckaid <0sAwEAAesFfVZqFzRA9F>
7. The output of the previous command generated the leftrsasigkey= line required for the
configuration. Do the same on the second host (right):
# ipsec showhostkey --right --ckaid <0sAwEAAesFfVZqFzRA9E>
8. Enable the ipsec service to automatically start it on boot:
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2
3
4
5
6
7
8
9
10
# systemctl enable --now ipsec
9. Create a YAML file, for example ~/create-rsa-authentication.yml, with the following content:
The YAML file defines the following settings:
An IPsec connection name
An interface name
The value 99 means that libreswan creates an IPsec xfrm virtual interface
ipsec<number> and automatically finds the next available number
The RSA public key of a local host
A static IPv4 address of public network interface of a local host
A Distinguished Name (DN) for a local host
The RSA public key of a remote host
A static IPv4 address of public network interface of a remote host
A Distinguished Name(DN) for a remote host
insist value accepts and receives only the Internet Key Exchange (IKEv2) protocol
10. Apply the settings to the system:
# nmstatectl apply ~/create-rsa-authentication.yml
Verification
1. Display the IP settings of the network interface:
# ip addr show example_ipsec_conn1
---
interfaces:
- name: 'example_ipsec_conn1' 1
type: ipsec 2
ipv4:
enabled: true
dhcp: true
libreswan:
ipsec-interface: '99' 3
leftrsasigkey: '0sAwEAAesFfVZqFzRA9F' 4
left: '192.0.2.250' 5
leftid: 'local-host-rsa.example.com' 6
right: '192.0.2.150' 7
rightrsasigkey: '0sAwEAAesFfVZqFzRA9E' 8
rightid: 'remote-host-rsa.example.com' 9
ikev2: 'insist' 10
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2. Verify IPsec status:
# ip xfrm status
3. Verify IPsec policies:
# ip xfrm policy
Additional resources
ipsec.conf(5) man page
7.5.3. Configuring a host-to-subnet IPSec VPN with PSK authentication and tunnel
mode by using nmstatectl
If you want to use encryption based on mutual authentication in IPsec, the Pre-Shared Key (PSK)
method provides secure communication by using a secret key between two hosts. A file stores the
secret key and the same key encrypts the data flowing through the tunnel.
By using Nmstate, a declarative API for network management, you can configure PSK-based IPsec
authentication. After setting the configuration, the Nmstate API ensures that the result matches with
the configuration file. If anything fails, nmstate automatically rolls back the changes to avoid incorrect
state of the system.
To establish encrypted communication in host-to-subnet configuration, remote IPsec end provides
another IP to host by using parameter dhcp: true. In the case of defining systems for IPsec in nmstate,
the left-named system is the local host while the right-named system is the remote host. The following
procedure needs to run on both hosts.
NOTE
As this method uses static strings for authentication and encryption, use it only for
testing/development purposes.
Procedure
1. Install the required packages:
# dnf install nmstate libreswan NetworkManager-libreswan
2. Restart the NetworkManager service:
# systemctl restart NetworkManager
3. If Libreswan was already installed, remove its old database files and re-create them:
# systemctl stop ipsec
# rm /etc/ipsec.d/*db
# ipsec initnss
4. Enable the ipsec service to automatically start it on boot:
# systemctl enable --now ipsec
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1
2
3
4
5
6
7
5. Create a YAML file, for example ~/create-pks-authentication.yml, with the following content:
The YAML file defines the following settings:
An IPsec connection name
Setting no value indicates that libreswan creates only xfrm policies, and not a virtual xfrm
interface
A static IPv4 address of public network interface of a remote host
A Distinguished Name (DN) for a remote host
A static IPv4 address of public network interface of a local host
A Distinguished Name (DN) for a local host
insist value accepts and receives only the Internet Key Exchange (IKEv2) protocol
6. Apply the settings to the system:
# nmstatectl apply ~/create-pks-authentication.yml
Verification
1. Display the IP settings of network interface:
# ip addr show example_ipsec_conn1
2. Verify IPsec status:
# ip xfrm status
3. Verify IPsec policies:
# ip xfrm policy
---
interfaces:
- name: 'example_ipsec_conn1' 1
type: ipsec
ipv4:
enabled: true
dhcp: true
libreswan:
ipsec-interface: 'no' 2
right: '192.0.2.250' 3
rightid: 'remote-host.example.org' 4
left: '192.0.2.150' 5
leftid: 'local-host.example.org' 6
psk: "example_password"
ikev2: 'insist' 7
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7.5.4. Configuring a host-to-host IPsec VPN with PKI authentication and tunnel
mode by using nmstatectl
IPsec (Internet Protocol Security) is a security protocol suite to authenticate and encrypt IP
communications within networks and devices. The Libreswan software provides an IPsec
implementation for VPNs.
In tunnel mode, the source and destination IP address of communication is encrypted in the IPsec
tunnel. External network sniffers can only get left IP and right IP. In general, for tunnel mode, it supports
host-to-host, host-to-subnet, and subnet-to-subnet. In this mode, a new IP packet encapsulates an
existing packet along with its payload and header. Encapsulation in this mode protects IP data, source,
and destination headers over an unsecure network. This mode is useful to transfer data in subnet-to-
subnet, remote access connections, and untrusted networks, such as open public Wi-Fi networks. By
default, IPsec establishes a secure channel between two sites in tunnel mode. With the following
configuration, you can establish a VPN connection as a host-to-host architecture.
By using Nmstate, a declarative API for network management, you can configure an IPsec VPN
connection. After setting the configuration, the Nmstate API ensures that the result matches with the
configuration file. If anything fails, nmstate automatically rolls back the changes to avoid incorrect state
of the system.
In host-to-host configuration, you need to set leftmodecfgclient: no so that it can’t receive network
configuration from the server, hence the value no. In the case of defining systems for IPsec in nmstate,
the left-named system is the local host while the right-named system is the remote host. The following
procedure needs to run on both hosts.
Prerequisites
By using a password, you have generated a PKCS #12 file that stores certificates and
cryptographic keys.
Procedure
1. Install the required packages:
# dnf install nmstate libreswan NetworkManager-libreswan
2. Restart the NetworkManager service:
# systemctl restart NetworkManager
3. As Libreswan was already installed, remove its old database files and re-create them:
# systemctl stop ipsec
# rm /etc/ipsec.d/*db
# ipsec initnss
4. Import the PKCS#12 file:
# ipsec import node-example.p12
When importing the PKCS#12 file, enter the password that was used to generate the file.
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1
2
3
4
5
6
7
8
9
5. Enable and start the ipsec service:
# systemctl enable --now ipsec
6. Create a YAML file, for example ~/create-p2p-vpn-authentication.yml, with the following
content:
The YAML file defines the following settings:
An IPsec connection name
A static IPv4 address of public network interface for a local host
A distinguished Name (DN) of a local host
A certificate name installed on a local host
The value for not to retrieve client configuration from a remote host
A static IPv4 address of public network interface for a remote host
A distinguished Name (DN) of a remote host
The subnet range of a remote host - 192.0.2.150 with 32 IPv4 addresses
The value to accept and receive only the Internet Key Exchange (IKEv2) protocol
7. Apply the settings to the system:
# nmstatectl apply ~/create-p2p-vpn-authentication.yml
Verification
1. Display the created P2P policy:
# ip xfrm policy
2. Verify IPsec status:
---
interfaces:
- name: 'example_ipsec_conn1' 1
type: ipsec
libreswan:
left: '192.0.2.250' 2
leftid: 'local-host.example.com' 3
leftcert: 'local-host.example.com' 4
leftmodecfgclient: 'no' 5
right: '192.0.2.150' 6
rightid: 'remote-host.example.com' 7
rightsubnet: '192.0.2.150/32' 8
ikev2: 'insist' 9
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# ip xfrm status
Additional resources
ipsec.conf(5) man page
7.5.5. Configuring a host-to-host IPsec VPN with PSK authentication and transport
mode by using nmstatectl
IPsec (Internet Protocol Security) is a security protocol suite to authenticate and encrypt IP
communications within networks and devices. The Libreswan utility provides IPsec based
implementation for VPN.
In transport mode, encryption works only for the payload of an IP packet. Also, a new IPsec header gets
appended to the IP packet by keeping the original IP header as it is. Transport mode does not encrypt
the source and destination IP of communication but copies them to an external IP header. Hence,
encryption protects only IP data across the network. This mode is useful to transfer data in a host-to-
host connection of a network. This mode is often used along with the GRE tunnel to save 20 bytes (IP
header) of overheads. By default, the IPsec utility uses tunnel mode. To use transfer mode, set type:
transport for host-to-host connection data transfer.
By using Nmstate, a declarative API for network management, you can configure an IPsec VPN
connection. After setting the configuration, the Nmstate API ensures that the result matches with the
configuration file. If anything fails, nmstate automatically rolls back the changes to avoid incorrect state
of the system. To override the default tunnel mode, specify transport mode.
In the case of defining systems for IPsec in nmstate, the left-named system is the local host while the
right-named system is the remote host. The following procedure needs to run on both hosts.
Prerequisites
By using a password, you have generated a PKCS #12 file that stores certificates and
cryptographic keys.
Procedure
1. Install the required packages:
# dnf install nmstate libreswan NetworkManager-libreswan
2. Restart the NetworkManager service:
# systemctl restart NetworkManager
3. As Libreswan was already installed, remove its old database files and re-create them:
# systemctl stop ipsec
# rm /etc/ipsec.d/*db
# ipsec initnss
4. Import the PKCS#12 file:
# ipsec import node-example.p12
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2
3
4
5
6
7
8
9
10
11
12
When importing the PKCS#12 file, enter the password that was used to create the file.
5. Enable and start the ipsec service:
# systemctl enable --now ipsec
6. Create a YAML file, for example ~/create-p2p-transport-authentication.yml, with the following
content:
The YAML file defines the following settings:
An IPsec connection name
An IPsec mode
The value 99 means that libreswan creates an IPsec xfrm virtual interface
ipsec<number> and automatically finds the next available number
A static IPv4 address of public network interface for a local host
On a local host, the value of %fromcert sets the ID to a Distinguished Name (DN) which is
fetched from a loaded certificate
A Distinguished Name (DN) of a local host’s public key
A static IPv4 address of public network interface for a remote host
The subnet mask of a static IPv4 address of a local host
On a remote host, the value of %fromcert sets the ID to a Distinguished Name (DN) which
is fetched from a loaded certificate
The value to accept and receive only the Internet Key Exchange (IKEv2) protocol
The duration of IKE protocol
The duration of IPsec security association (SA)
---
interfaces:
- name: 'example_ipsec_conn1' 1
type: ipsec
libreswan:
type: 'transport' 2
ipsec-interface: '99' 3
left: '192.0.2.250' 4
leftid: '%fromcert' 5
leftcert: 'local-host.example.org' 6
right: '192.0.2.150' 7
prefix-length: '32' 8
rightid: '%fromcert' 9
ikev2: 'insist' 10
ikelifetime: '24h' 11
salifetime: '24h' 12
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7. Apply the settings to the system:
# nmstatectl apply ~/create-p2p-transport-authentication.yml
Verification
1. Verify IPsec status:
# ip xfrm status
2. Verify IPsec policies:
# ip xfrm policy
Additional resources
ipsec.conf(5) man page
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CHAPTER 8. SETTING UP A WIREGUARD VPN
WireGuard is a high-performance VPN solution that runs in the Linux kernel. It uses modern
cryptography and is easier to configure than many other VPN solutions. Additionally, WireGuard’s small
codebase reduces the surface for attacks and, therefore, improves security. For authentication and
encryption, WireGuard uses keys similar to SSH.
IMPORTANT
WireGuard is provided as a Technology Preview only. Technology Preview features are
not supported with Red Hat production Service Level Agreements (SLAs), might not be
functionally complete, and Red Hat does not recommend using them for production.
These previews provide early access to upcoming product features, enabling customers
to test functionality and provide feedback during the development process.
See Technology Preview Features Support Scope on the Red Hat Customer Portal for
information about the support scope for Technology Preview features.
Note that all hosts that participate in a WireGuard VPN are peers. This documentation uses the terms
client to describe hosts that establish a connection and server to describe the host with the fixed
hostname or IP address that the clients connect to and optionally route all traffic through this server.
To set up a WireGuard VPN, you must complete the following steps. You can perform most steps by
using different options:
1. Create public and private keys for every host in the VPN .
2. Configure the WireGuard server by using nmcli, nmtui, the RHEL web console, nm-connection-
editor, or the wg-quick service.
3. Configure firewalld on the WireGuard server by using the command line, the RHEL web console,
or graphical interface.
4. Configure the WireGuard client by using nmcli, nmtui, the RHEL web console, nm-connection-
editor, or the wg-quick service.
WireGuard operates on the network layer (layer 3). Therefore, you cannot use DHCP and must assign
static IP addresses or IPv6 link-local addresses to the tunnel devices on both the server and clients.
IMPORTANT
You can use WireGuard only if the Federal Information Processing Standard (FIPS)
mode in RHEL is disabled.
8.1. PROTOCOLS AND PRIMITIVES USED BY WIREGUARD
WireGuard uses the following protocols and primitives:
ChaCha20 for symmetric encryption, authenticated with Poly1305, using Authenticated
Encryption with Associated Data (AEAD) construction as described in RFC7539
Curve25519 for Elliptic-curve Diffie–Hellman (ECDH) key exchange
BLAKE2s for hashing and keyed hashing, as described in RFC7693
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SipHash24 for hash table keys
HKDF for key derivation, as described in RFC5869
8.2. HOW WIREGUARD USES TUNNEL IP ADDRESSES, PUBLIC KEYS,
AND REMOTE ENDPOINTS
When WireGuard sends a network packet to a peer:
1. WireGuard reads the destination IP from the packet and compares it to the list of allowed IP
addresses in the local configuration. If the peer is not found, WireGuard drops the packet.
2. If the peer is valid, WireGuard encrypts the packet using the peer’s public key.
3. The sending host looks up the most recent Internet IP address of the host and sends the
encrypted packet to it.
When WireGuard receives a packet:
1. WireGuard decrypts the packet using the private key of the remote host.
2. WireGuard reads the internal source address from the packet and looks up whether the IP is
configured in the list of allowed IP addresses in the settings for the peer on the local host. If the
source IP is on the allowlist, WireGuard accepts the packet. If the IP address is not on the list,
WireGuard drops the packet.
The association of public keys and allowed IP addresses is called Cryptokey Routing Table. This means
that the list of IP addresses behaves similar to a routing table when sending packets, and as a kind of
access control list when receiving packets.
8.3. USING A WIREGUARD CLIENT BEHIND NAT AND FIREWALLS
WireGuard uses the UDP protocol and transmits data only when a peer sends packets. Stateful firewalls
and network address translation (NAT) on routers track connections to enable a peer behind NAT or a
firewall to receive packets.
To keep the connection active, WireGuard supports persistent keepalives. This means you can set an
interval at which WireGuard sends keepalive packets. By default, the persistent keep-alive feature is
disabled to reduce network traffic. Enable this feature on the client if you use the client in a network with
NAT or if a firewall closes the connection after some time of inactivity.
NOTE
Note that you cannot configure keepalive packets in WireGuard connections by using the
RHEL web console. To configure this feature, edit the connection profile by using the
nmcli utility.
8.4. CREATING PRIVATE AND PUBLIC KEYS TO BE USED IN
WIREGUARD CONNECTIONS
WireGuard uses base64-encoded private and public keys to authenticate hosts to each other.
Therefore, you must create the keys on each host that participates in the WireGuard VPN.
IMPORTANT
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IMPORTANT
For secure connections, create different keys for each host, and ensure that you only
share the public key with the remote WireGuard host. Do not use the example keys used
in this documentation.
If you plan to use the RHEL web console to create a WireGuard VPN connection, you can, alternatively,
generate the public and private key pairs in the web console.
Procedure
1. Install the wireguard-tools package:
# dnf install wireguard-tools
2. Create a private key and a corresponding public key for the host:
# wg genkey | tee /etc/wireguard/$HOSTNAME.private.key | wg pubkey >
/etc/wireguard/$HOSTNAME.public.key
You will need the content of the key files, but not the files themselves. However, Red Hat
recommends keeping the files in case that you need to remember the keys in future.
3. Set secure permissions on the key files:
# chmod 600 /etc/wireguard/$HOSTNAME.private.key
/etc/wireguard/$HOSTNAME.public.key
4. Display the private key:
# cat /etc/wireguard/$HOSTNAME.private.key
YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg=
You will need the private key to configure the WireGuard connection on the local host. Do not
share the private key.
5. Display the public key:
# cat /etc/wireguard/$HOSTNAME.public.key
UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
You will need the public key to configure the WireGuard connection on the remote host.
Additional resources
The wg(8) man page
8.5. CONFIGURING A WIREGUARD SERVER BY USING NMCLI
You can configure the WireGuard server by creating a connection profile in NetworkManager. Use this
method to let NetworkManager manage the WireGuard connection.
This procedure assumes the following settings:
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Server:
Private key: YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg=
Tunnel IPv4 address: 192.0.2.1/24
Tunnel IPv6 address: 2001:db8:1::1/32
Client:
Public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
Tunnel IPv4 address: 192.0.2.2/24
Tunnel IPv6 address: 2001:db8:1::2/32
Prerequisites
You have generated the public and private key for both the server and client.
You know the following information:
The private key of the server
The static tunnel IP addresses and subnet masks of the client
The public key of the client
The static tunnel IP addresses and subnet masks of the server
Procedure
1. Add a NetworkManager WireGuard connection profile:
# nmcli connection add type wireguard con-name server-wg0 ifname wg0 autoconnect
no
This command creates a profile named server-wg0 and assigns the virtual interface wg0 to it.
To prevent the connection from starting automatically after you add it without finalizing the
configuration, disable the autoconnect parameter.
2. Set the tunnel IPv4 address and subnet mask of the server:
# nmcli connection modify server-wg0 ipv4.method manual ipv4.addresses
192.0.2.1/24
3. Set the tunnel IPv6 address and subnet mask of the server:
# nmcli connection modify server-wg0 ipv6.method manual ipv6.addresses
2001:db8:1::1/32
4. Add the server’s private key to the connection profile:
# nmcli connection modify server-wg0 wireguard.private-key
"YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg="
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5. Set the port for incoming WireGuard connections:
# nmcli connection modify server-wg0 wireguard.listen-port 51820
Always set a fixed port number on hosts that receive incoming WireGuard connections. If you do
not set a port, WireGuard uses a random free port each time you activate the wg0 interface.
6. Add peer configurations for each client that you want to allow to communicate with this server.
You must add these settings manually, because the nmcli utility does not support setting the
corresponding connection properties.
a. Edit the /etc/NetworkManager/system-connections/server-wg0.nmconnection file, and
append:
[wireguard-peer.bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=]
allowed-ips=192.0.2.2;2001:db8:1::2;
The [wireguard-peer.<public_key_of_the_client>] entry defines the peer section of
the client, and the section name contains the public key of the client.
The allowed-ips parameter sets the tunnel IP addresses of the client that are allowed
to send data to this server.
Add a section for each client.
b. Reload the server-wg0 connection profile:
# nmcli connection load /etc/NetworkManager/system-connections/server-
wg0.nmconnection
7. Optional: Configure the connection to start automatically, enter:
# nmcli connection modify server-wg0 autoconnect yes
8. Reactivate the server-wg0 connection:
# nmcli connection up server-wg0
Next steps
Configure the firewalld service on the WireGuard server.
Verification
1. Display the interface configuration of the wg0 device:
# wg show wg0
interface: wg0
public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
private key: (hidden)
listening port: 51820
peer: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
allowed ips: 192.0.2.2/32, 2001:db8:1::2/128
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To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0
command.
2. Display the IP configuration of the wg0 device:
# ip address show wg0
20: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state
UNKNOWN group default qlen 1000
link/none
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute wg0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::1/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::3ef:8863:1ce2:844/64 scope link noprefixroute
valid_lft forever preferred_lft forever
Additional resources
The wg(8) man page
The WireGuard setting section in the nm-settings(5) man page
8.6. CONFIGURING A WIREGUARD SERVER BY USING NMTUI
You can configure the WireGuard server by creating a connection profile in NetworkManager. Use this
method to let NetworkManager manage the WireGuard connection.
This procedure assumes the following settings:
Server:
Private key: YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg=
Tunnel IPv4 address: 192.0.2.1/24
Tunnel IPv6 address: 2001:db8:1::1/32
Client:
Public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
Tunnel IPv4 address: 192.0.2.2/24
Tunnel IPv6 address: 2001:db8:1::2/32
Prerequisites
You have generated the public and private key for both the server and client.
You know the following information:
The private key of the server
The static tunnel IP addresses and subnet masks of the client
The public key of the client
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The static tunnel IP addresses and subnet masks of the server
You installed the NetworkManager-tui package.
Procedure
1. Start the nmtui application:
# nmtui
2. Select Edit a connection, and press Enter.
3. Select Add, and press Enter.
4. Select the WireGuard connection type in the list, and press Enter.
5. In the Edit connection window:
a. Enter the name of the connection and the virtual interface, such as wg0, that
NetworkManager should assign to the connection.
b. Enter the private key of the server.
c. Set the listen port number, such as 51820, for incoming WireGuard connections.
Always set a fixed port number on hosts that receive incoming WireGuard connections. If
you do not set a port, WireGuard uses a random free port each time you activate the
interface.
d. Click Add next to the Peers pane:
i. Enter the public key of the client.
ii. Set the Allowed IPs field to the tunnel IP addresses of the client that are allowed to
send data to this server.
iii. Select OK, and press Enter.
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e. Select Show next to *IPv4 Configuration, and press Enter.
i. Select the IPv4 configuration method Manual.
ii. Enter the tunnel IPv4 address and the subnet mask. Leave the Gateway field empty.
f. Select Show next to IPv6 Configuration, and press Enter.
i. Select the IPv6 configuration method Manual.
ii. Enter the tunnel IPv6 address and the subnet mask. Leave the Gateway field empty.
g. Select OK, and press Enter
6. In the window with the list of connections, select Back, and press Enter.
7. In the NetworkManager TUI main window, select Quit, and press Enter.
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Next steps
Configure the firewalld service on the WireGuard server.
Verification
1. Display the interface configuration of the wg0 device:
# wg show wg0
interface: wg0
public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
private key: (hidden)
listening port: 51820
peer: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
allowed ips: 192.0.2.2/32, 2001:db8:1::2/128
To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0
command.
2. Display the IP configuration of the wg0 device:
# ip address show wg0
20: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state
UNKNOWN group default qlen 1000
link/none
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute wg0
valid_lft forever preferred_lft forever
inet6 _2001:db8:1::1/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::3ef:8863:1ce2:844/64 scope link noprefixroute
valid_lft forever preferred_lft forever
Additional resources
The wg(8) man page
8.7. CONFIGURING A WIREGUARD SERVER BY USING THE RHEL WEB
CONSOLE
You can configure a WireGuard server by using the browser-based RHEL web console. Use this method
to let NetworkManager manage the WireGuard connection.
Prerequisites
You are logged in to the RHEL web console.
You know the following information:
The static tunnel IP addresses and subnet masks of both the server and client
The public key of the client
Procedure
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1. Select the Networking tab in the navigation on the left side of the screen.
2. Click Add VPN in the Interfaces section.
3. If the wireguard-tools and systemd-resolved packages are not already installed, the web
console displays a corresponding notification. Click Install to install these packages.
4. Enter the name of the WireGuard device that you want to create.
5. Configure the key pair of this host:
If you want use the keys that the web console has created:
i. Keep the pre-selected Generated option in the Private key area.
ii. Note the Public key value. You require this information when you configure the client.
If you want to use an existing private key:
i. Select Paste existing key in the Private key area.
ii. Paste the private key into the text field. The web console automatically calculates the
corresponding public key.
6. Set a listen port number, such as 51820, for incoming WireGuard connections.
Always set a fixed port number on hosts that receive incoming WireGuard connections. If you do
not set a port, WireGuard uses a random free port each time you activate the interface.
7. Set the tunnel IPv4 address and subnet mask of the server.
To also set an IPv6 address, you must edit the connection after you have created it.
8. Add peer configurations for each client that you want to allow to communicate with this server:
a. Click Add peer.
b. Enter the public key of the client.
c. Leave the Endpoint field empty.
d. Set the Allowed IPs field to the tunnel IP addresses of the clients that are allowed to send
data to this server.
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9. Click Add to create the WireGuard connection.
10. If you want to also set a tunnel IPv6 address:
a. Click on the WireGuard connection’s name in the Interfaces section.
b. Click edit next to IPv6.
c. Set the Addresses field to Manual, and enter the tunnel IPv6 address and prefix of the
server.
d. Click Save.
Next steps
Configure the firewalld service on the WireGuard server.
Verification
1. Display the interface configuration of the wg0 device:
# wg show wg0
interface: wg0
public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
private key: (hidden)
listening port: 51820
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peer: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
allowed ips: 192.0.2.2/32, 2001:db8:1::2/128
To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0
command.
2. Display the IP configuration of the wg0 device:
# ip address show wg0
20: wg0: <POINTOPOINT,NOARP,UP,LOWERUP> mtu 1420 qdisc noqueue state
UNKNOWN group default qlen 1000
link/none
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute wg0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::1/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::3ef:8863:1ce2:844/64 scope link noprefixroute
valid_lft forever preferred_lft forever
8.8. CONFIGURING A WIREGUARD SERVER BY USING NM-
CONNECTION-EDITOR
You can configure the WireGuard server by creating a connection profile in NetworkManager. Use this
method to let NetworkManager manage the WireGuard connection.
Prerequisites
You have generated the public and private key for both the server and client.
You know the following information:
The private key of the server
The static tunnel IP addresses and subnet masks of the client
The public key of the client
The static tunnel IP addresses and subnet masks of the server
Procedure
1. Open a terminal, and enter:
# nm-connection-editor
2. Add a new connection by clicking the + button.
3. Select the WireGuard connection type, and click Create.
4. Optional: Update the connection name.
5. On the General tab, select Connect automatically with priority. Optionally, set a priority value.
6. On the WireGuard tab:
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a. Enter the name of the virtual interface, such as wg0, that NetworkManager should assign to
the connection.
b. Enter the private key of the server.
c. Set the listen port number, such as 51820, for incoming WireGuard connections.
Always set a fixed port number on hosts that receive incoming WireGuard connections. If
you do not set a port, WireGuard uses a random free port each time you activate the
interface.
d. Click Add to add peers:
i. Enter the public key of the client.
ii. Set the Allowed IPs field to the tunnel IP addresses of the client that are allowed to
send data to this server.
iii. Click Apply.
7. On the IPv4 Settings tab:
a. Select Manual in the Method list.
b. Click Add to enter the tunnel IPv4 address and the subnet mask. Leave the Gateway field
empty.
8. On the IPv6 Settings tab:
a. Select Manual in the Method list.
b. Click Add to enter the tunnel IPv6 address and the subnet mask. Leave the Gateway field
empty.
9. Click Save to store the connection profile.
Next steps
Configure the firewalld service on the WireGuard server.
Verification
1. Display the interface configuration of the wg0 device:
# wg show wg0
interface: wg0
public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
private key: (hidden)
listening port: 51820
peer: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
allowed ips: 192.0.2.2/32, 2001:db8:1::2/128
To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0
command.
2. Display the IP configuration of the wg0 device:
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# ip address show wg0
20: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state
UNKNOWN group default qlen 1000
link/none
inet 192.0.2.1/24 brd 192.0.2.255 scope global noprefixroute wg0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::1/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::3ef:8863:1ce2:844/64 scope link noprefixroute
valid_lft forever preferred_lft forever
Additional resources
The wg(8) man page
8.9. CONFIGURING A WIREGUARD SERVER BY USING THE WG-QUICK
SERVICE
You can configure the WireGuard server by creating a configuration file in the /etc/wireguard/ directory.
Use this method to configure the service independently from NetworkManager.
This procedure assumes the following settings:
Server:
Private key: YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg=
Tunnel IPv4 address: 192.0.2.1/24
Tunnel IPv6 address: 2001:db8:1::1/32
Client:
Public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
Tunnel IPv4 address: 192.0.2.2/24
Tunnel IPv6 address: 2001:db8:1::2/32
Prerequisites
You have generated the public and private key for both the server and client.
You know the following information:
The private key of the server
The static tunnel IP addresses and subnet masks of the client
The public key of the client
The static tunnel IP addresses and subnet masks of the server
Procedure
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1. Install the wireguard-tools package:
# dnf install wireguard-tools
2. Create the /etc/wireguard/wg0.conf file with the following content:
[Interface]
Address = 192.0.2.1/24, 2001:db8:1::1/32
ListenPort = 51820
PrivateKey = YFAnE0psgIdiAF7XR4abxiwVRnlMfeltxu10s/c4JXg=
[Peer]
PublicKey = bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
AllowedIPs = 192.0.2.2, 2001:db8:1::2
The [Interface] section describes the WireGuard settings of the interface on the server:
Address: A comma-separated list of the server’s tunnel IP addresses.
PrivateKey: The private key of the server.
ListenPort: The port on which WireGuard listens for incoming UDP connections.
Always set a fixed port number on hosts that receive incoming WireGuard connections.
If you do not set a port, WireGuard uses a random free port each time you activate the
wg0 interface.
Each [Peer] section describes the settings of one client:
PublicKey: The public key of the client.
AllowedIPs: The tunnel IP addresses of the client that are allowed to send data to this
server.
3. Enable and start the WireGuard connection:
# systemctl enable --now wg-quick@wg0
The systemd instance name must match the name of the configuration file in the
/etc/wireguard/ directory without the .conf suffix. The service also uses this name for the
virtual network interface.
Next steps
Configure the firewalld service on the WireGuard server.
Verification
1. Display the interface configuration of the wg0 device:
# wg show wg0
interface: wg0
public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
private key: (hidden)
listening port: 51820
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peer: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
allowed ips: 192.0.2.2/32, 2001:db8:1::2/128
To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0
command.
2. Display the IP configuration of the wg0 device:
# ip address show wg0
20: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state
UNKNOWN group default qlen 1000
link/none
inet 192.0.2.1/24 scope global wg0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::1/32 scope global
valid_lft forever preferred_lft forever
Additional resources
The wg(8) man page
The wg-quick(8) man page
8.10. CONFIGURING FIREWALLD ON A WIREGUARD SERVER BY USING
THE COMMAND LINE
You must configure the firewalld service on the WireGuard server to allow incoming connections from
clients. Additionally, if clients should be able to use the WireGuard server as the default gateway and
route all traffic through the tunnel, you must enable masquerading.
Procedure
1. Open the WireGuard port for incoming connections in the firewalld service:
# firewall-cmd --permanent --add-port=51820/udp --zone=public
2. If clients should route all traffic through the tunnel and use the WireGuard server as the default
gateway, enable masquerading for the public zone:
# firewall-cmd --permanent --zone=public --add-masquerade
3. Reload the firewalld rules.
# firewall-cmd --reload
Verification
Display the configuration of the public zone:
# firewall-cmd --list-all
public (active)
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...
ports: 51820/udp
masquerade: yes
...
Additional resources
The firewall-cmd(1) man page
8.11. CONFIGURING FIREWALLD ON A WIREGUARD SERVER BY USING
THE RHEL WEB CONSOLE
You must configure the firewalld service on the WireGuard server to allow incoming connections from
clients. Additionally, if clients should be able to use the WireGuard server as the default gateway and
route all traffic through the tunnel, you must enable masquerading.
Prerequisites
You are logged in to the RHEL web console.
Procedure
1. Select the Networking tab in the navigation on the left side of the screen.
2. Click Edit rules and zones in the Firewall section.
3. Enter wireguard into the Filter services field.
4. Select the wireguard entry from the list.
5. Click Add services.
6. If clients should route all traffic through the tunnel and use the WireGuard server as the default
gateway, enable masquerading for the public zone:
# firewall-cmd --permanent --zone=public --add-masquerade
# firewall-cmd --reload
Note that you cannot enable masquerading in firewalld zones in the web console.
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Verification
1. Select the Networking tab in the navigation on the left side of the screen.
2. Click Edit rules and zones in the Firewall section.
3. The list contains an entry for the wireguard service and displays the UDP port that you
configured in the WireGuard connection profile.
4. To verify that masquerading is enabled in the firewalld public zone, enter:
# firewall-cmd --list-all --zone=public
public (active)
...
ports: 51820/udp
masquerade: yes
...
8.12. CONFIGURING FIREWALLD ON A WIREGUARD SERVER BY USING
THE GRAPHICAL INTERFACE
You must configure the firewalld service on the WireGuard server to allow incoming connections from
clients. Additionally, if clients should be able to use the WireGuard server as the default gateway and
route all traffic through the tunnel, you must enable masquerading.
Procedure
1. Press the Super key, enter firewall, and select the Firewall application from the results.
2. Select Permanent in the Configuration list.
3. Select the public zone.
4. Allow incoming connections to the WireGuard port:
a. On the Ports tab, click Add.
b. Enter the port number you set for incoming WireGuard connections:
c. Select udp from the Protocol list.
d. Click OK.
5. If clients should route all traffic through the tunnel and use the WireGuard server as the default
gateway:
a. Navigate to the Masquerading tab of the public zone.
b. Select Masquerade zone.
6. Select Options → Reload Firewalld.
Verification
Display the configuration of the public zone:
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# firewall-cmd --list-all
public (active)
...
ports: 51820/udp
masquerade: yes
...
8.13. CONFIGURING A WIREGUARD CLIENT BY USING NMCLI
You can configure a WireGuard client by creating a connection profile in NetworkManager. Use this
method to let NetworkManager manage the WireGuard connection.
This procedure assumes the following settings:
Client:
Private key: aPUcp5vHz8yMLrzk8SsDyYnV33IhE/k20e52iKJFV0A=
Tunnel IPv4 address: 192.0.2.2/24
Tunnel IPv6 address: 2001:db8:1::2/32
Server:
Public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
Tunnel IPv4 address: 192.0.2.1/24
Tunnel IPv6 address: 2001:db8:1::1/32
Prerequisites
You have generated the public and private key for both the server and client.
You know the following information:
The private key of the client
The static tunnel IP addresses and subnet masks of the client
The public key of the server
The static tunnel IP addresses and subnet masks of the server
Procedure
1. Add a NetworkManager WireGuard connection profile:
# nmcli connection add type wireguard con-name client-wg0 ifname wg0 autoconnect
no
This command creates a profile named client-wg0 and assigns the virtual interface wg0 to it. To
prevent the connection from starting automatically after you add it without finalizing the
configuration, disable the autoconnect parameter.
2. Optional: Configure NetworkManager so that it does not automatically start the client-wg
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2. Optional: Configure NetworkManager so that it does not automatically start the client-wg
connection:
# nmcli connection modify client-wg0 autoconnect no
3. Set the tunnel IPv4 address and subnet mask of the client:
# nmcli connection modify client-wg0 ipv4.method manual ipv4.addresses 192.0.2.2/24
4. Set the tunnel IPv6 address and subnet mask of the client:
# nmcli connection modify client-wg0 ipv6.method manual ipv6.addresses
2001:db8:1::2/32
5. If you want to route all traffic through the tunnel, set the tunnel IP addresses of the server as
the default gateway:
# nmcli connection modify client-wg0 ipv4.gateway 192.0.2.1 ipv6.gateway
2001:db8:1::1
Routing all traffic through the tunnel requires that you set, in a later step, the allowed-ips on
the this client to 0.0.0.0/0;::/0.
Note that routing all traffic through the tunnel can impact the connectivity to other hosts based
on the server routing and firewall configuration.
6. Add the client’s private key to the connection profile:
# nmcli connection modify client-wg0 wireguard.private-key
"aPUcp5vHz8yMLrzk8SsDyYnV33IhE/k20e52iKJFV0A="
7. Add peer configurations for each server that you want to allow to communicate with this client.
You must add these settings manually, because the nmcli utility does not support setting the
corresponding connection properties.
a. Edit the /etc/NetworkManager/system-connections/client-wg0.nmconnection file, and
append:
[wireguard-peer.UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=]
endpoint=server.example.com:51820
allowed-ips=192.0.2.1;2001:db8:1::1;
persistent-keepalive=20
The [wireguard-peer.<public_key_of_the_server>] entry defines the peer section of
the server, and the section name has the public key of the server.
The endpoint parameter sets the hostname or IP address and the port of the server.
The client uses this information to establish the connection.
The allowed-ips parameter sets a list of IP addresses that can send data to this client.
For example, set the parameter to:
The tunnel IP addresses of the server to allow only the server to communicate with
this client. The value in the example above configures this scenario.
0.0.0.0/0;::/0; to allow any remote IPv4 and IPv6 address to communicate with this
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0.0.0.0/0;::/0; to allow any remote IPv4 and IPv6 address to communicate with this
client. Use this setting to route all traffic through the tunnel and use the WireGuard
server as default gateway.
The optional persistent-keepalive parameter defines an interval in seconds in which
WireGuard sends a keep alive packet to the server. Set this parameter if you use the
client in a network with network address translation (NAT) or if a firewall closes the UDP
connection after some time of inactivity.
b. Reload the client-wg0 connection profile:
# nmcli connection load /etc/NetworkManager/system-connections/client-
wg0.nmconnection
8. Reactivate the client-wg0 connection:
# nmcli connection up client-wg0
Verification
1. Ping the IP addresses of the server:
# ping 192.0.2.1
# ping6 2001:db8:1::1
2. Display the interface configuration of the wg0 device:
# wg show wg0
interface: wg0
public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
private key: (hidden)
listening port: 51820
peer: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
endpoint: server.example.com:51820
allowed ips: 192.0.2.1/32, 2001:db8:1::1/128
latest handshake: 1 minute, 41 seconds ago
transfer: 824 B received, 1.01 KiB sent
persistent keepalive: every 20 seconds
To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0
command.
Note that the output has only the latest handshake and transfer entries if you have already
sent traffic through the VPN tunnel.
3. Display the IP configuration of the wg0 device:
# ip address show wg0
10: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state
UNKNOWN group default qlen 1000
link/none
inet 192.0.2.2/24 brd 192.0.2.255 scope global noprefixroute wg0
valid_lft forever preferred_lft forever
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inet6 2001:db8:1::2/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::73d9:6f51:ea6f:863e/64 scope link noprefixroute
valid_lft forever preferred_lft forever
Additional resources
The wg(8) man page
The WireGuard setting section in the nm-settings(5) man page
8.14. CONFIGURING A WIREGUARD CLIENT BY USING NMTUI
You can configure a WireGuard client by creating a connection profile in NetworkManager. Use this
method to let NetworkManager manage the WireGuard connection.
This procedure assumes the following settings:
Client:
Private key: aPUcp5vHz8yMLrzk8SsDyYnV33IhE/k20e52iKJFV0A=
Tunnel IPv4 address: 192.0.2.2/24
Tunnel IPv6 address: 2001:db8:1::2/32
Server:
Public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
Tunnel IPv4 address: 192.0.2.1/24
Tunnel IPv6 address: 2001:db8:1::1/32
Prerequisites
You have generated the public and private key for both the server and client.
You know the following information:
The private key of the client
The static tunnel IP addresses and subnet masks of the client
The public key of the server
The static tunnel IP addresses and subnet masks of the server
You installed the NetworkManager-tui package
Procedure
1. Start the nmtui application:
# nmtui
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2. Select Edit a connection, and press Enter.
3. Select Add, and press Enter.
4. Select the WireGuard connection type in the list, and press Enter.
5. In the Edit connection window:
a. Enter the name of the connection and the virtual interface, such as wg0, that
NetworkManager should assign to the connection.
b. Enter the private key of the client.
c. Click Add next to the Peers pane:
i. Enter the public key of the server.
ii. Set the Allowed IPs field. For example, set it to:
The tunnel IP addresses of the server to allow only the server to communicate with
this client.
0.0.0.0/0,::/0 to allow any remote IPv4 and IPv6 address to communicate with this
client. Use this setting to route all traffic through the tunnel and use the WireGuard
server as default gateway.
iii. Enter the host name or IP address and port of the WireGuard server into the Endpoint
field. Use the following format: <hostname_or_IP>:<port_number>
iv. Optional: If you use the client in a network with network address translation (NAT) or if a
firewall closes the UDP connection after some time of inactivity, set a persistent keep
alive interval in seconds. In this interval, the client sends a keepalive packet to the server.
v. Select OK, and press Enter.
d. Select Show next to IPv4 Configuration, and press Enter.
i. Select the IPv4 configuration method Manual.
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ii. Enter the tunnel IPv4 address and the subnet mask. Leave the Gateway field empty.
e. Select Show next to IPv6 Configuration, and press Enter.
i. Select the IPv6 configuration method Manual.
ii. Enter the tunnel IPv6 address and the subnet mask. Leave the Gateway field empty.
f. Optional: Select Automatically connect.
g. Select OK, and press Enter
6. In the window with the list of connections, select Back, and press Enter.
7. In the NetworkManager TUI main window, select Quit, and press Enter.
Verification
1. Ping the IP addresses of the server:
# ping 192.0.2.1
# ping6 2001:db8:1::1
2. Display the interface configuration of the wg0 device:
# wg show wg0
interface: wg0
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public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
private key: (hidden)
listening port: 51820
peer: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
endpoint: server.example.com:51820_
allowed ips: 192.0.2.1/32, 2001:db8:1::1/128
latest handshake: 1 minute, 41 seconds ago
transfer: 824 B received, 1.01 KiB sent
persistent keepalive: every 20 seconds
To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0
command.
Note that the output contains only the latest handshake and transfer entries if you have
already sent traffic through the VPN tunnel.
3. Display the IP configuration of the wg0 device:
# ip address show wg0
10: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state
UNKNOWN group default qlen 1000
link/none
inet 192.0.2.2/24 brd 192.0.2.255 scope global noprefixroute wg0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::2/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::73d9:6f51:ea6f:863e/64 scope link noprefixroute
valid_lft forever preferred_lft forever
Additional resources
The wg(8) man page
8.15. CONFIGURING A WIREGUARD CLIENT BY USING THE RHEL WEB
CONSOLE
You can configure a WireGuard client by using the browser-based RHEL web console. Use this method
to let NetworkManager manage the WireGuard connection.
Prerequisites
You are logged in to the RHEL web console.
You know the following information:
The static tunnel IP addresses and subnet masks of both the server and client
The public key of the server
Procedure
1. Select the Networking tab in the navigation on the left side of the screen.
2. Click Add VPN in the Interfaces section.
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3. If the wireguard-tools and systemd-resolved packages are not already installed, the web
console displays a corresponding notification. Click Install to install these packages.
4. Enter the name of the WireGuard device that you want to create.
5. Configure the key pair of this host:
If you want use the keys that the web console has created:
i. Keep the pre-selected Generated option in the Private key area.
ii. Note the Public key value. You require this information when you configure the client.
If you want to use an existing private key:
i. Select Paste existing key in the Private key area.
ii. Paste the private key into the text field. The web console automatically calculates the
corresponding public key.
6. Preserve the 0 value in the Listen port field.
7. Set the tunnel IPv4 address and subnet mask of the client.
To also set an IPv6 address, you must edit the connection after you have created it.
8. Add a peer configuration for the server that you want to allow to communicate with this client:
a. Click Add peer.
b. Enter the public key of the server.
c. Set the Endpoint field to the hostname or IP address and the port of the server, for
example server.example.com:51820. The client uses this information to establish the
connection.
d. Set the Allowed IPs field to the tunnel IP addresses of the clients that are allowed to send
data to this server. For example, set the field to one of the following:
The tunnel IP addresses of the server to allow only the server to communicate with this
client. The value in the screen capture below configures this scenario.
0.0.0.0/0 to allow any remote IPv4 address to communicate with this client. Use this
setting to route all traffic through the tunnel and use the WireGuard server as default
gateway.
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9. Click Add to create the WireGuard connection.
10. If you want to also set a tunnel IPv6 address:
a. Click on the WireGuard connection’s name in the Interfaces section.
b. Click Edit next to IPv6.
c. Set the Addresses field to Manual, and enter the tunnel IPv6 address and prefix of the
client.
d. Click Save.
Verification
1. Ping the IP addresses of the server:
# ping 192.0.2.1
WireGuard establishes the connection when you try to send traffic through the tunnel.
2. Display the interface configuration of the wg0 device:
# wg show wg0
interface: wg0
public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
private key: (hidden)
listening port: 45513
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peer: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
endpoint: server.example.com:51820
allowed ips: 192.0.2.1/32, 2001:db8:1::1/128
latest handshake: 1 minute, 41 seconds ago
transfer: 824 B received, 1.01 KiB sent
persistent keepalive: every 20 seconds
To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0
command.
Note that the output has only the latest handshake and transfer entries if you have already
sent traffic through the VPN tunnel.
3. Display the IP configuration of the wg0 device:
# ip address show wg0
10: wg0: <POINTOPOINT,NOARP,UP,LOWERUP> mtu 1420 qdisc noqueue state
UNKNOWN group default qlen 1000
link/none
inet 192.0.2.2/24 brd 192.0.2.255 scope global noprefixroute wg0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::2/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::73d9:6f51:ea6f:863e/64 scope link noprefixroute
valid_lft forever preferred_lft forever
8.16. CONFIGURING A WIREGUARD CLIENT BY USING NM-
CONNECTION-EDITOR
You can configure a WireGuard client by creating a connection profile in NetworkManager. Use this
method to let NetworkManager manage the WireGuard connection.
Prerequisites
You have generated the public and private key for both the server and client.
You know the following information:
The private key of the client
The static tunnel IP addresses and subnet masks of the client
The public key of the server
The static tunnel IP addresses and subnet masks of the server
Procedure
1. Open a terminal, and enter:
# nm-connection-editor
2. Add a new connection by clicking the + button.
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171
3. Select the WireGuard connection type, and click Create.
4. Optional: Update the connection name.
5. Optional: On the General tab, select Connect automatically with priority.
6. On the WireGuard tab:
a. Enter the name of the virtual interface, such as wg0, that NetworkManager should assign to
the connection.
b. Enter client’s private key.
c. Click Add to add peers:
i. Enter the public key of the server.
ii. Set the Allowed IPs field. For example, set it to:
The tunnel IP addresses of the server to allow only the server to communicate with
this client.
0.0.0.0/0;::/0; to allow any remote IPv4 and IPv6 address to communicate with this
client. Use this setting to route all traffic through the tunnel and use the WireGuard
server as default gateway.
Note that routing all traffic through the tunnel can impact the connectivity to other
hosts based on the server routing and firewall configuration.
iii. Enter the hostname or IP address and port of the WireGuard server into the Endpoint
field. Use the following format: <hostname_or_IP<:<port_number>
iv. Optional: If you use the client in a network with network address translation (NAT) or if a
firewall closes the UDP connection after some time of inactivity, set a persistent keep
alive interval in seconds. In this interval, the client sends a keep alive packet to the
server.
v. Click Apply.
7. On the IPv4 Settings tab:
a. Select Manual in the Method list.
b. Click Add to enter the tunnel IPv4 address and the subnet mask.
c. If you want to route all traffic through the tunnel, set the tunnel IPv4 address of the server
in the Gateway field. Otherwise, leave the field empty.
Routing all IPv4 traffic through the tunnel requires that you included 0.0.0.0/0 in the
Allowed IPs field on this client.
8. On the IPv6 Settings tab:
a. Select Manual in the Method list.
b. Click Add to enter the tunnel IPv6 address and the subnet mask.
c. If you want to route all traffic through the tunnel, set the tunnel IPv6 address of the server
in the Gateway field. Otherwise, leave the field empty.
Routing all IPv4 traffic through the tunnel requires that you included ::/0 in the Allowed IPs
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Routing all IPv4 traffic through the tunnel requires that you included ::/0 in the Allowed IPs
field on this client.
9. Click Save to store the connection profile.
Verification
1. Ping the IP addresses of the server:
# ping 192.0.2.1
# ping6 2001:db8:1::1
2. Display the interface configuration of the wg0 device:
# wg show wg0
interface: wg0
public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
private key: (hidden)
listening port: 51820
peer: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
endpoint: server.example.com:51820
allowed ips: 192.0.2.1/32, 2001:db8:1::1/128
latest handshake: 1 minute, 41 seconds ago
transfer: 824 B received, 1.01 KiB sent
persistent keepalive: every 20 seconds
To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0
command.
Note that the output only has the latest handshake and transfer entries if you have already
sent traffic through the VPN tunnel.
3. Display the IP configuration of the wg0 device:
# ip address show wg0
10: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state
UNKNOWN group default qlen 1000
link/none
inet 192.0.2.2/24 brd 192.0.2.255 scope global noprefixroute wg0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::2/32 scope global noprefixroute
valid_lft forever preferred_lft forever
inet6 fe80::73d9:6f51:ea6f:863e/64 scope link noprefixroute
valid_lft forever preferred_lft forever
Additional resources
The wg(8) man page
8.17. CONFIGURING A WIREGUARD CLIENT BY USING THE WG-QUICK
SERVICE
You can configure a WireGuard client by creating a configuration file in the /etc/wireguard/ directory.
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You can configure a WireGuard client by creating a configuration file in the /etc/wireguard/ directory.
Use this method to configure the service independently from NetworkManager.
This procedure assumes the following settings:
Client:
Private key: aPUcp5vHz8yMLrzk8SsDyYnV33IhE/k20e52iKJFV0A=
Tunnel IPv4 address: 192.0.2.2/24
Tunnel IPv6 address: 2001:db8:1::2/32
Server:
Public key: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
Tunnel IPv4 address: 192.0.2.1/24
Tunnel IPv6 address: 2001:db8:1::1/32
Prerequisites
You have generated the public and private key for both the server and client.
You know the following information:
The private key of the client
The static tunnel IP addresses and subnet masks of the client
The public key of the server
The static tunnel IP addresses and subnet masks of the server
Procedure
1. Install the wireguard-tools package:
# dnf install wireguard-tools
2. Create the /etc/wireguard/wg0.conf file with the following content:
[Interface]
Address = 192.0.2.2/24, 2001:db8:1::2/32
PrivateKey = aPUcp5vHz8yMLrzk8SsDyYnV33IhE/k20e52iKJFV0A=
[Peer]
PublicKey = UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
AllowedIPs = 192.0.2.1, 2001:db8:1::1
Endpoint = server.example.com:51820
PersistentKeepalive = 20
The [Interface] section describes the WireGuard settings of the interface on the client:
Address: A comma-separated list of the client’s tunnel IP addresses.
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PrivateKey: The private key of the client.
The [Peer] section describes the settings of the server:
PublicKey: The public key of the server.
AllowedIPs: The IP addresses that are allowed to send data to this client. For example,
set the parameter to:
The tunnel IP addresses of the server to allow only the server to communicate with
this client. The value in the example above configures this scenario.
0.0.0.0/0, ::/0 to allow any remote IPv4 and IPv6 address to communicate with this
client. Use this setting to route all traffic through the tunnel and use the WireGuard
server as default gateway.
Endpoint: Sets the hostname or IP address and the port of the server. The client uses
this information to establish the connection.
The optional persistent-keepalive parameter defines an interval in seconds in which
WireGuard sends a keepalive packet to the server. Set this parameter if you use the
client in a network with network address translation (NAT) or if a firewall closes the UDP
connection after some time of inactivity.
3. Enable and start the WireGuard connection:
# systemctl enable --now wg-quick@wg0
The systemd instance name must match the name of the configuration file in the
/etc/wireguard/ directory without the .conf suffix. The service also uses this name for the
virtual network interface.
Verification
1. Ping the IP addresses of the server:
# ping 192.0.2.1
# ping6 2001:db8:1::1
2. Display the interface configuration of the wg0 device:
# wg show wg0
interface: wg0
public key: bnwfQcC8/g2i4vvEqcRUM2e6Hi3Nskk6G9t4r26nFVM=
private key: (hidden)
listening port: 51820
peer: UtjqCJ57DeAscYKRfp7cFGiQqdONRn69u249Fa4O6BE=
endpoint: server.example.com:51820
allowed ips: 192.0.2.1/32, 2001:db8:1::1/128
latest handshake: 1 minute, 41 seconds ago
transfer: 824 B received, 1.01 KiB sent
persistent keepalive: every 20 seconds
To display the private key in the output, use the WG_HIDE_KEYS=never wg show wg0
command.
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Note that the output contains only the latest handshake and transfer entries if you have
already sent traffic through the VPN tunnel.
3. Display the IP configuration of the wg0 device:
# ip address show wg0
10: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state
UNKNOWN group default qlen 1000
link/none
inet 192.0.2.2/24 scope global wg0
valid_lft forever preferred_lft forever
inet6 2001:db8:1::2/32 scope global
valid_lft forever preferred_lft forever
Additional resources
The wg(8) man page
The wg-quick(8) man page
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CHAPTER 9. CONFIGURING IP TUNNELS
Similar to a VPN, an IP tunnel directly connects two networks over a third network, such as the internet.
However, not all tunnel protocols support encryption.
The routers in both networks that establish the tunnel requires at least two interfaces:
One interface that is connected to the local network
One interface that is connected to the network through which the tunnel is established.
To establish the tunnel, you create a virtual interface on both routers with an IP address from the
remote subnet.
NetworkManager supports the following IP tunnels:
Generic Routing Encapsulation (GRE)
Generic Routing Encapsulation over IPv6 (IP6GRE)
Generic Routing Encapsulation Terminal Access Point (GRETAP)
Generic Routing Encapsulation Terminal Access Point over IPv6 (IP6GRETAP)
IPv4 over IPv4 (IPIP)
IPv4 over IPv6 (IPIP6)
IPv6 over IPv6 (IP6IP6)
Simple Internet Transition (SIT)
Depending on the type, these tunnels act either on layer 2 or 3 of the Open Systems Interconnection
(OSI) model.
9.1. CONFIGURING AN IPIP TUNNEL TO ENCAPSULATE IPV4 TRAFFIC
IN IPV4 PACKETS
An IP over IP (IPIP) tunnel operates on OSI layer 3 and encapsulates IPv4 traffic in IPv4 packets as
described in RFC 2003.
IMPORTANT
Data sent through an IPIP tunnel is not encrypted. For security reasons, use the tunnel
only for data that is already encrypted, for example, by other protocols, such as HTTPS.
Note that IPIP tunnels support only unicast packets. If you require an IPv4 tunnel that supports
multicast, see Configuring a GRE tunnel to encapsulate layer-3 traffic in IPv4 packets .
For example, you can create an IPIP tunnel between two RHEL routers to connect two internal subnets
over the internet as shown in the following diagram:
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Prerequisites
Each RHEL router has a network interface that is connected to its local subnet.
Each RHEL router has a network interface that is connected to the internet.
The traffic you want to send through the tunnel is IPv4 unicast.
Procedure
1. On the RHEL router in network A:
a. Create an IPIP tunnel interface named tun0:
# nmcli connection add type ip-tunnel ip-tunnel.mode ipip con-name tun0 ifname
tun0 remote 198.51.100.5 local 203.0.113.10
The remote and local parameters set the public IP addresses of the remote and the local
routers.
b. Set the IPv4 address to the tun0 device:
# nmcli connection modify tun0 ipv4.addresses '10.0.1.1/30'
Note that a /30 subnet with two usable IP addresses is sufficient for the tunnel.
c. Configure the tun0 connection to use a manual IPv4 configuration:
# nmcli connection modify tun0 ipv4.method manual
d. Add a static route that routes traffic to the 172.16.0.0/24 network to the tunnel IP on router
B:
# nmcli connection modify tun0 +ipv4.routes "172.16.0.0/24 10.0.1.2"
e. Enable the tun0 connection.
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# nmcli connection up tun0
f. Enable packet forwarding:
# echo "net.ipv4.ip_forward=1" > /etc/sysctl.d/95-IPv4-forwarding.conf
# sysctl -p /etc/sysctl.d/95-IPv4-forwarding.conf
2. On the RHEL router in network B:
a. Create an IPIP tunnel interface named tun0:
# nmcli connection add type ip-tunnel ip-tunnel.mode ipip con-name tun0 ifname
tun0 remote 203.0.113.10 local 198.51.100.5
The remote and local parameters set the public IP addresses of the remote and local
routers.
b. Set the IPv4 address to the tun0 device:
# nmcli connection modify tun0 ipv4.addresses '10.0.1.2/30'
c. Configure the tun0 connection to use a manual IPv4 configuration:
# nmcli connection modify tun0 ipv4.method manual
d. Add a static route that routes traffic to the 192.0.2.0/24 network to the tunnel IP on router
A:
# nmcli connection modify tun0 +ipv4.routes "192.0.2.0/24 10.0.1.1"
e. Enable the tun0 connection.
# nmcli connection up tun0
f. Enable packet forwarding:
# echo "net.ipv4.ip_forward=1" > /etc/sysctl.d/95-IPv4-forwarding.conf
# sysctl -p /etc/sysctl.d/95-IPv4-forwarding.conf
Verification
From each RHEL router, ping the IP address of the internal interface of the other router:
a. On Router A, ping 172.16.0.1:
# ping 172.16.0.1
b. On Router B, ping 192.0.2.1:
# ping 192.0.2.1
9.2. CONFIGURING A GRE TUNNEL TO ENCAPSULATE LAYER-3
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9.2. CONFIGURING A GRE TUNNEL TO ENCAPSULATE LAYER-3
TRAFFIC IN IPV4 PACKETS
A Generic Routing Encapsulation (GRE) tunnel encapsulates layer-3 traffic in IPv4 packets as described
in RFC 2784. A GRE tunnel can encapsulate any layer 3 protocol with a valid Ethernet type.
IMPORTANT
Data sent through a GRE tunnel is not encrypted. For security reasons, use the tunnel
only for data that is already encrypted, for example, by other protocols, such as HTTPS.
For example, you can create a GRE tunnel between two RHEL routers to connect two internal subnets
over the internet as shown in the following diagram:
Prerequisites
Each RHEL router has a network interface that is connected to its local subnet.
Each RHEL router has a network interface that is connected to the internet.
Procedure
1. On the RHEL router in network A:
a. Create a GRE tunnel interface named gre1:
# nmcli connection add type ip-tunnel ip-tunnel.mode gre con-name gre1 ifname
gre1 remote 198.51.100.5 local 203.0.113.10
The remote and local parameters set the public IP addresses of the remote and the local
routers.
IMPORTANT
The gre0 device name is reserved. Use gre1 or a different name for the
device.
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b. Set the IPv4 address to the gre1 device:
# nmcli connection modify gre1 ipv4.addresses '10.0.1.1/30'
Note that a /30 subnet with two usable IP addresses is sufficient for the tunnel.
c. Configure the gre1 connection to use a manual IPv4 configuration:
# nmcli connection modify gre1 ipv4.method manual
d. Add a static route that routes traffic to the 172.16.0.0/24 network to the tunnel IP on router
B:
# nmcli connection modify gre1 +ipv4.routes "172.16.0.0/24 10.0.1.2"
e. Enable the gre1 connection.
# nmcli connection up gre1
f. Enable packet forwarding:
# echo "net.ipv4.ip_forward=1" > /etc/sysctl.d/95-IPv4-forwarding.conf
# sysctl -p /etc/sysctl.d/95-IPv4-forwarding.conf
2. On the RHEL router in network B:
a. Create a GRE tunnel interface named gre1:
# nmcli connection add type ip-tunnel ip-tunnel.mode gre con-name gre1 ifname
gre1 remote 203.0.113.10 local 198.51.100.5
The remote and local parameters set the public IP addresses of the remote and the local
routers.
b. Set the IPv4 address to the gre1 device:
# nmcli connection modify gre1 ipv4.addresses '10.0.1.2/30'
c. Configure the gre1 connection to use a manual IPv4 configuration:
# nmcli connection modify gre1 ipv4.method manual
d. Add a static route that routes traffic to the 192.0.2.0/24 network to the tunnel IP on router
A:
# nmcli connection modify gre1 +ipv4.routes "192.0.2.0/24 10.0.1.1"
e. Enable the gre1 connection.
# nmcli connection up gre1
f. Enable packet forwarding:
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# echo "net.ipv4.ip_forward=1" > /etc/sysctl.d/95-IPv4-forwarding.conf
# sysctl -p /etc/sysctl.d/95-IPv4-forwarding.conf
Verification
1. From each RHEL router, ping the IP address of the internal interface of the other router:
a. On Router A, ping 172.16.0.1:
# ping 172.16.0.1
b. On Router B, ping 192.0.2.1:
# ping 192.0.2.1
9.3. CONFIGURING A GRETAP TUNNEL TO TRANSFER ETHERNET
FRAMES OVER IPV4
A Generic Routing Encapsulation Terminal Access Point (GRETAP) tunnel operates on OSI level 2 and
encapsulates Ethernet traffic in IPv4 packets as described in RFC 2784.
IMPORTANT
Data sent through a GRETAP tunnel is not encrypted. For security reasons, establish the
tunnel over a VPN or a different encrypted connection.
For example, you can create a GRETAP tunnel between two RHEL routers to connect two networks
using a bridge as shown in the following diagram:
Prerequisites
Each RHEL router has a network interface that is connected to its local network, and the
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Each RHEL router has a network interface that is connected to its local network, and the
interface has no IP configuration assigned.
Each RHEL router has a network interface that is connected to the internet.
Procedure
1. On the RHEL router in network A:
a. Create a bridge interface named bridge0:
# nmcli connection add type bridge con-name bridge0 ifname bridge0
b. Configure the IP settings of the bridge:
# nmcli connection modify bridge0 ipv4.addresses '192.0.2.1/24'
# nmcli connection modify bridge0 ipv4.method manual
c. Add a new connection profile for the interface that is connected to local network to the
bridge:
# nmcli connection add type ethernet port-type bridge con-name bridge0-port1
ifname enp1s0 controller bridge0
d. Add a new connection profile for the GRETAP tunnel interface to the bridge:
# nmcli connection add type ip-tunnel ip-tunnel.mode gretap port-type bridge con-
name bridge0-port2 ifname gretap1 remote 198.51.100.5 local 203.0.113.10
controller bridge0
The remote and local parameters set the public IP addresses of the remote and the local
routers.
IMPORTANT
The gretap0 device name is reserved. Use gretap1 or a different name for
the device.
e. Optional: Disable the Spanning Tree Protocol (STP) if you do not need it:
# nmcli connection modify bridge0 bridge.stp no
By default, STP is enabled and causes a delay before you can use the connection.
f. Configure that activating the bridge0 connection automatically activates the ports of the
bridge:
# nmcli connection modify bridge0 connection.autoconnect-ports 1
g. Active the bridge0 connection:
# nmcli connection up bridge0
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2. On the RHEL router in network B:
a. Create a bridge interface named bridge0:
# nmcli connection add type bridge con-name bridge0 ifname bridge0
b. Configure the IP settings of the bridge:
# nmcli connection modify bridge0 ipv4.addresses '192.0.2.2/24'
# nmcli connection modify bridge0 ipv4.method manual
c. Add a new connection profile for the interface that is connected to local network to the
bridge:
# nmcli connection add type ethernet port-type bridge con-name bridge0-port1
ifname enp1s0 controller bridge0
d. Add a new connection profile for the GRETAP tunnel interface to the bridge:
# nmcli connection add type ip-tunnel ip-tunnel.mode gretap port-type bridge con-
name bridge0-port2 ifname gretap1 remote 203.0.113.10 local 198.51.100.5
controller bridge0
The remote and local parameters set the public IP addresses of the remote and the local
routers.
e. Optional: Disable the Spanning Tree Protocol (STP) if you do not need it:
# nmcli connection modify bridge0 bridge.stp no
f. Configure that activating the bridge0 connection automatically activates the ports of the
bridge:
# nmcli connection modify bridge0 connection.autoconnect-ports 1
g. Active the bridge0 connection:
# nmcli connection up bridge0
Verification
1. On both routers, verify that the enp1s0 and gretap1 connections are connected and that the
CONNECTION column displays the connection name of the port:
# nmcli device
nmcli device
DEVICE TYPE STATE CONNECTION
...
bridge0 bridge connected bridge0
enp1s0 ethernet connected bridge0-port1
gretap1 iptunnel connected bridge0-port2
2. From each RHEL router, ping the IP address of the internal interface of the other router:
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a. On Router A, ping 192.0.2.2:
# ping 192.0.2.2
b. On Router B, ping 192.0.2.1:
# ping 192.0.2.1
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CHAPTER 10. USING A VXLAN TO CREATE A VIRTUAL LAYER-
2 DOMAIN FOR VMS
A virtual extensible LAN (VXLAN) is a networking protocol that tunnels layer-2 traffic over an IP network
using the UDP protocol. For example, certain virtual machines (VMs), that are running on different hosts
can communicate over a VXLAN tunnel. The hosts can be in different subnets or even in different data
centers around the world. From the perspective of the VMs, other VMs in the same VXLAN are within
the same layer-2 domain:
In this example, RHEL-host-A and RHEL-host-B use a bridge, br0, to connect the virtual network of a
VM on each host with a VXLAN named vxlan10. Due to this configuration, the VXLAN is invisible to the
VMs, and the VMs do not require any special configuration. If you later connect more VMs to the same
virtual network, the VMs are automatically members of the same virtual layer-2 domain.
IMPORTANT
Just as normal layer-2 traffic, data in a VXLAN is not encrypted. For security reasons, use
a VXLAN over a VPN or other types of encrypted connections.
10.1. BENEFITS OF VXLANS
A virtual extensible LAN (VXLAN) provides the following major benefits:
VXLANs use a 24-bit ID. Therefore, you can create up to 16,777,216 isolated networks. For
example, a virtual LAN (VLAN), supports only 4,096 isolated networks.
VXLANs use the IP protocol. This enables you to route the traffic and virtually run systems in
different networks and locations within the same layer-2 domain.
Unlike most tunnel protocols, a VXLAN is not only a point-to-point network. A VXLAN can learn
the IP addresses of the other endpoints either dynamically or use statically-configured
forwarding entries.
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Certain network cards support UDP tunnel-related offload features.
Additional resources
/usr/share/doc/kernel-doc-<kernel_version>/Documentation/networking/vxlan.rst provided
by the kernel-doc package
10.2. CONFIGURING THE ETHERNET INTERFACE ON THE HOSTS
To connect a RHEL VM host to the Ethernet, create a network connection profile, configure the IP
settings, and activate the profile.
Run this procedure on both RHEL hosts, and adjust the IP address configuration accordingly.
Prerequisites
The host is connected to the Ethernet.
Procedure
1. Add a new Ethernet connection profile to NetworkManager:
# nmcli connection add con-name Example ifname enp1s0 type ethernet
2. Configure the IPv4 settings:
# nmcli connection modify Example ipv4.addresses 198.51.100.2/24 ipv4.method
manual ipv4.gateway 198.51.100.254 ipv4.dns 198.51.100.200 ipv4.dns-search
example.com
Skip this step if the network uses DHCP.
3. Activate the Example connection:
# nmcli connection up Example
Verification
1. Display the status of the devices and connections:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp1s0 ethernet connected Example
2. Ping a host in a remote network to verify the IP settings:
# ping RHEL-host-B.example.com
Note that you cannot ping the other VM host before you have configured the network on that
host as well.
Additional resources
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nm-settings(5) man page
10.3. CREATING A NETWORK BRIDGE WITH A VXLAN ATTACHED
To make a virtual extensible LAN (VXLAN) invisible to virtual machines (VMs), create a bridge on a host,
and attach the VXLAN to the bridge. Use NetworkManager to create both the bridge and the VXLAN.
You do not add any traffic access point (TAP) devices of the VMs, typically named vnet* on the host, to
the bridge. The libvirtd service adds them dynamically when the VMs start.
Run this procedure on both RHEL hosts, and adjust the IP addresses accordingly.
Procedure
1. Create the bridge br0:
# nmcli connection add type bridge con-name br0 ifname br0 ipv4.method disabled
ipv6.method disabled
This command sets no IPv4 and IPv6 addresses on the bridge device, because this bridge works
on layer 2.
2. Create the VXLAN interface and attach it to br0:
# nmcli connection add type vxlan port-type bridge con-name br0-vxlan10 ifname
vxlan10 id 10 local 198.51.100.2 remote 203.0.113.1 controller br0
This command uses the following settings:
id 10: Sets the VXLAN identifier.
local 198.51.100.2: Sets the source IP address of outgoing packets.
remote 203.0.113.1: Sets the unicast or multicast IP address to use in outgoing packets
when the destination link layer address is not known in the VXLAN device forwarding
database.
controller br0: Sets this VXLAN connection to be created as a port in the br0 connection.
ipv4.method disabled and ipv6.method disabled: Disables IPv4 and IPv6 on the bridge.
By default, NetworkManager uses 8472 as the destination port. If the destination port is
different, additionally, pass the destination-port <port_number> option to the command.
3. Activate the br0 connection profile:
# nmcli connection up br0
4. Open port 8472 for incoming UDP connections in the local firewall:
# firewall-cmd --permanent --add-port=8472/udp
# firewall-cmd --reload
Verification
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Display the forwarding table:
# bridge fdb show dev vxlan10
2a:53:bd:d5:b3:0a master br0 permanent
00:00:00:00:00:00 dst 203.0.113.1 self permanent
...
Additional resources
nm-settings(5) man page
10.4. CREATING A VIRTUAL NETWORK IN LIBVIRT WITH AN EXISTING
BRIDGE
To enable virtual machines (VM) to use the br0 bridge with the attached virtual extensible LAN
(VXLAN), first add a virtual network to the libvirtd service that uses this bridge.
Prerequisites
You installed the libvirt package.
You started and enabled the libvirtd service.
You configured the br0 device with the VXLAN on RHEL.
Procedure
1. Create the ~/vxlan10-bridge.xml file with the following content:
<network>
<name>vxlan10-bridge</name>
<forward mode="bridge" />
<bridge name="br0" />
</network>
2. Use the ~/vxlan10-bridge.xml file to create a new virtual network in libvirt:
# virsh net-define ~/vxlan10-bridge.xml
3. Remove the ~/vxlan10-bridge.xml file:
# rm ~/vxlan10-bridge.xml
4. Start the vxlan10-bridge virtual network:
# virsh net-start vxlan10-bridge
5. Configure the vxlan10-bridge virtual network to start automatically when the libvirtd service
starts:
# virsh net-autostart vxlan10-bridge
Verification
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189
Verification
Display the list of virtual networks:
# virsh net-list
Name State Autostart Persistent
----------------------------------------------------
vxlan10-bridge active yes yes
...
Additional resources
virsh(1) man page
10.5. CONFIGURING VIRTUAL MACHINES TO USE VXLAN
To configure a VM to use a bridge device with an attached virtual extensible LAN (VXLAN) on the host,
create a new VM that uses the vxlan10-bridge virtual network or update the settings of existing VMs to
use this network.
Perform this procedure on the RHEL hosts.
Prerequisites
You configured the vxlan10-bridge virtual network in libvirtd.
Procedure
To create a new VM and configure it to use the vxlan10-bridge network, pass the --network
network:vxlan10-bridge option to the virt-install command when you create the VM:
# virt-install ... --network network:vxlan10-bridge
To change the network settings of an existing VM:
a. Connect the VM’s network interface to the vxlan10-bridge virtual network:
# virt-xml VM_name --edit --network network=vxlan10-bridge
b. Shut down the VM, and start it again:
# virsh shutdown VM_name
# virsh start VM_name
Verification
1. Display the virtual network interfaces of the VM on the host:
# virsh domiflist VM_name
Interface Type Source Model MAC
-------------------------------------------------------------------
vnet1 bridge vxlan10-bridge virtio 52:54:00:c5:98:1c
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2. Display the interfaces attached to the vxlan10-bridge bridge:
# ip link show master vxlan10-bridge
18: vxlan10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master
br0 state UNKNOWN mode DEFAULT group default qlen 1000
link/ether 2a:53:bd:d5:b3:0a brd ff:ff:ff:ff:ff:ff
19: vnet1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master
br0 state UNKNOWN mode DEFAULT group default qlen 1000
link/ether 52:54:00:c5:98:1c brd ff:ff:ff:ff:ff:ff
Note that the libvirtd service dynamically updates the bridge’s configuration. When you start a
VM which uses the vxlan10-bridge network, the corresponding vnet* device on the host
appears as a port of the bridge.
3. Use address resolution protocol (ARP) requests to verify whether VMs are in the same VXLAN:
a. Start two or more VMs in the same VXLAN.
b. Send an ARP request from one VM to the other one:
# arping -c 1 192.0.2.2
ARPING 192.0.2.2 from 192.0.2.1 enp1s0
Unicast reply from 192.0.2.2 [52:54:00:c5:98:1c] 1.450ms
Sent 1 probe(s) (0 broadcast(s))
Received 1 response(s) (0 request(s), 0 broadcast(s))
If the command shows a reply, the VM is in the same layer-2 domain and, in this case in the
same VXLAN.
Install the iputils package to use the arping utility.
Additional resources
virt-install(1) man page
virt-xml(1) man page
virsh(1) man page
arping(8) man page
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CHAPTER 11. MANAGING WIFI CONNECTIONS
RHEL provides multiple utilities and applications to configure and connect to wifi networks, for example:
Use the nmcli utility to configure connections by using the command line.
Use the nmtui application to configure connections in a text-based user interface.
Use the GNOME system menu to quickly connect to wifi networks that do not require any
configuration.
Use the GNOME Settings application to configure connections by using the GNOME
application.
Use the nm-connection-editor application to configure connections in a graphical user
interface.
Use the network RHEL system role to automate the configuration of connections on one or
multiple hosts.
11.1. SUPPORTED WIFI SECURITY TYPES
Depending on the security type a wifi network supports, you can transmitted data more or less securely.
WARNING
Do not connect to wifi networks that do not use encryption or which support only
the insecure WEP or WPA standards.
Red Hat Enterprise Linux 9 supports the following wifi security types:
None: Encryption is disabled, and data is transferred in plain text over the network.
Enhanced Open: With opportunistic wireless encryption (OWE), devices negotiate unique
pairwise master keys (PMK) to encrypt connections in wireless networks without authentication.
LEAP: The Lightweight Extensible Authentication Protocol, which was developed by Cisco, is a
proprietary version of the extensible authentication protocol (EAP).
WPA & WPA2 Personal: In personal mode, the Wi-Fi Protected Access (WPA) and Wi-Fi
Protected Access 2 (WPA2) authentication methods use a pre-shared key.
WPA & WPA2 Enterprise: In enterprise mode, WPA and WPA2 use the EAP framework and
authenticate users to a remote authentication dial-in user service (RADIUS) server.
WPA3 Personal: Wi-Fi Protected Access 3 (WPA3) Personal uses simultaneous authentication
of equals (SAE) instead of pre-shared keys (PSK) to prevent dictionary attacks. WPA3 uses
perfect forward secrecy (PFS).
11.2. CONNECTING TO A WIFI NETWORK BY USING NMCLI
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You can use the nmcli utility to connect to a wifi network. When you attempt to connect to a network
for the first time, the utility automatically creates a NetworkManager connection profile for it. If the
network requires additional settings, such as static IP addresses, you can then modify the profile after it
has been automatically created.
Prerequisites
A wifi device is installed on the host.
The wifi device is enabled, if it has a hardware switch.
Procedure
1. If the wifi radio has been disabled in NetworkManager, enable this feature:
# nmcli radio wifi on
2. Optional: Display the available wifi networks:
# nmcli device wifi list
IN-USE BSSID SSID MODE CHAN RATE SIGNAL BARS SECURITY
00:53:00:2F:3B:08 Office Infra 44 270 Mbit/s 57 ▂▄▆_ WPA2 WPA3
00:53:00:15:03:BF -- Infra 1 130 Mbit/s 48 ▂▄__ WPA2 WPA3
The service set identifier (SSID) column contains the names of the networks. If the column
shows --, the access point of this network does not broadcast an SSID.
3. Connect to the wifi network:
# nmcli device wifi connect Office --ask
Password: wifi-password
If you prefer to set the password in the command instead of entering it interactively, use the
password wifi-password option in the command instead of --ask:
# nmcli device wifi connect Office wifi-password
Note that, if the network requires static IP addresses, NetworkManager fails to activate the
connection at this point. You can configure the IP addresses in later steps.
4. If the network requires static IP addresses:
a. Configure the IPv4 address settings, for example:
# nmcli connection modify Office ipv4.method manual ipv4.addresses 192.0.2.1/24
ipv4.gateway 192.0.2.254 ipv4.dns 192.0.2.200 ipv4.dns-search example.com
b. Configure the IPv6 address settings, for example:
# nmcli connection modify Office ipv6.method manual ipv6.addresses
2001:db8:1::1/64 ipv6.gateway 2001:db8:1::fffe ipv6.dns 2001:db8:1::ffbb ipv6.dns-
search example.com
5. Re-activate the connection:
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# nmcli connection up Office
Verification
1. Display the active connections:
# nmcli connection show --active
NAME ID TYPE DEVICE
Office 2501eb7e-7b16-4dc6-97ef-7cc460139a58 wifi wlp0s20f3
If the output lists the wifi connection you have created, the connection is active.
2. Ping a hostname or IP address:
# ping -c 3 example.com
Additional resources
nm-settings-nmcli(5) man page
11.3. CONNECTING TO A WIFI NETWORK BY USING THE GNOME
SYSTEM MENU
You can use the GNOME system menu to connect to a wifi network. When you connect to a network for
the first time, GNOME creates a NetworkManager connection profile for it. If you configure the
connection profile to not automatically connect, you can also use the GNOME system menu to manually
connect to a wifi network with an existing NetworkManager connection profile.
NOTE
Using the GNOME system menu to establish a connection to a wifi network for the first
time has certain limitations. For example, you can not configure IP address settings. In
this case first configure the connections:
In the GNOME settings application
In the nm-connection-editor application
Using nmcli commands
Prerequisites
A wifi device is installed on the host.
The wifi device is enabled, if it has a hardware switch.
Procedure
1. Open the system menu on the right side of the top bar.
2. Expand the Wi-Fi Not Connected entry.
3. Click Select Network:
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4. Select the wifi network you want to connect to.
5. Click Connect.
6. If this is the first time you connect to this network, enter the password for the network, and click
Connect.
Verification
1. Open the system menu on the right side of the top bar, and verify that the wifi network is
connected:
If the network appears in the list, it is connected.
2. Ping a hostname or IP address:
# ping -c 3 example.com
11.4. CONNECTING TO A WIFI NETWORK BY USING THE GNOME
SETTINGS APPLICATION
You can use the GNOME settings application, also named gnome-control-center, to connect to a wifi
network and configure the connection. When you connect to the network for the first time, GNOME
creates a NetworkManager connection profile for it.
In GNOME settings, you can configure wifi connections for all wifi network security types that RHEL
supports.
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Prerequisites
A wifi device is installed on the host.
The wifi device is enabled, if it has a hardware switch.
Procedure
1. Press the Super key, type Wi-Fi, and press Enter.
2. Click on the name of the wifi network you want to connect to.
3. Enter the password for the network, and click Connect.
4. If the network requires additional settings, such as static IP addresses or a security type other
than WPA2 Personal:
a. Click the gear icon next to the network’s name.
b. Optional: Configure the network profile on the Details tab to not automatically connect.
If you deactivate this feature, you must always manually connect to the network, for
example, by using GNOME settings or the GNOME system menu.
c. Configure IPv4 settings on the IPv4 tab, and IPv6 settings on the IPv6 tab.
d. On the Security tab, select the authentication of the network, such as WPA3 Personal, and
enter the password.
Depending on the selected security, the application shows additional fields. Fill them
accordingly. For details, ask the administrator of the wifi network.
e. Click Apply.
Verification
1. Open the system menu on the right side of the top bar, and verify that the wifi network is
connected:
If the network appears in the list, it is connected.
2. Ping a hostname or IP address:
# ping -c 3 example.com
11.5. CONFIGURING A WIFI CONNECTION BY USING NMTUI
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The nmtui application provides a text-based user interface for NetworkManager. You can use nmtui to
connect to a wifi network.
NOTE
In nmtui:
Navigate by using the cursor keys.
Press a button by selecting it and hitting Enter.
Select and clear checkboxes by using Space.
Procedure
1. If you do not know the network device name you want to use in the connection, display the
available devices:
# nmcli device status
DEVICE TYPE STATE CONNECTION
wlp2s0 wifi unavailable --
...
2. Start nmtui:
# nmtui
3. Select Edit a connection, and press Enter.
4. Press the Add button.
5. Select Wi-Fi from the list of network types, and press Enter.
6. Optional: Enter a name for the NetworkManager profile to be created.
On hosts with multiple profiles, a meaningful name makes it easier to identify the purpose of a
profile.
7. Enter the network device name into the Device field.
8. Enter the name of the Wi-Fi network, the Service Set Identifier (SSID), into the SSID field.
9. Leave the Mode field set to its default, Client.
10. Select the Security field, press Enter, and set the authentication type of the network from the
list.
Depending on the authentication type you have selected, nmtui displays different fields.
11. Fill the authentication type-related fields.
12. If the Wi-Fi network requires static IP addresses:
a. Press the Automatic button next to the protocol, and select Manual from the displayed list.
b. Press the Show button next to the protocol you want to configure to display additional
fields, and fill them.
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13. Press the OK button to create and automatically activate the new connection.
14. Press the Back button to return to the main menu.
15. Select Quit, and press Enter to close the nmtui application.
Verification
1. Display the active connections:
# nmcli connection show --active
NAME ID TYPE DEVICE
Office 2501eb7e-7b16-4dc6-97ef-7cc460139a58 wifi wlp0s20f3
If the output lists the wifi connection you have created, the connection is active.
2. Ping a hostname or IP address:
# ping -c 3 example.com
11.6. CONFIGURING A WIFI CONNECTION BY USING NM-
CONNECTION-EDITOR
You can use the nm-connection-editor application to create a connection profile for a wireless network.
In this application you can configure all wifi network authentication types that RHEL supports.
By default, NetworkManager enables the auto-connect feature for connection profiles and
automatically connects to a saved network if it is available.
Prerequisites
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A wifi device is installed on the host.
The wifi device is enabled, if it has a hardware switch.
Procedure
1. Open a terminal and enter:
# nm-connection-editor
2. Click the + button to add a new connection.
3. Select the Wi-Fi connection type, and click Create.
4. Optional: Set a name for the connection profile.
5. Optional: Configure the network profile on the General tab to not automatically connect.
If you deactivate this feature, you must always manually connect to the network, for example, by
using GNOME settings or the GNOME system menu.
6. On the Wi-Fi tab, enter the service set identifier (SSID) in the SSID field.
7. On the Wi-Fi Security tab, select the authentication type for the network, such as WPA3
Personal, and enter the password.
Depending on the selected security, the application shows additional fields. Fill them
accordingly. For details, ask the administrator of the wifi network.
8. Configure IPv4 settings on the IPv4 tab, and IPv6 settings on the IPv6 tab.
9. Click Save.
10. Close the Network Connections window.
Verification
1. Open the system menu on the right side of the top bar, and verify that the wifi network is
connected:
If the network appears in the list, it is connected.
2. Ping a hostname or IP address:
# ping -c 3 example.com
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11.7. CONFIGURING A WIFI CONNECTION WITH 802.1X NETWORK
AUTHENTICATION BY USING THE NETWORK RHEL SYSTEM ROLE
Network Access Control (NAC) protects a network from unauthorized clients. You can specify the
details that are required for the authentication in NetworkManager connection profiles to enable clients
to access the network. By using Ansible and the network RHEL system role, you can automate this
process and remotely configure connection profiles on the hosts defined in a playbook.
You can use an Ansible playbook to copy a private key, a certificate, and the CA certificate to the client,
and then use the network RHEL system role to configure a connection profile with 802.1X network
authentication.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
The network supports 802.1X network authentication.
You installed the wpa_supplicant package on the managed node.
DHCP is available in the network of the managed node.
The following files required for TLS authentication exist on the control node:
The client key is stored in the /srv/data/client.key file.
The client certificate is stored in the /srv/data/client.crt file.
The CA certificate is stored in the /srv/data/ca.crt file.
Procedure
1. Store your sensitive variables in an encrypted file:
a. Create the vault:
$ ansible-vault create vault.yml
New Vault password: <vault_password>
Confirm New Vault password: <vault_password>
b. After the ansible-vault create command opens an editor, enter the sensitive data in the
<key>: <value> format:
c. Save the changes, and close the editor. Ansible encrypts the data in the vault.
2. Create a playbook file, for example ~/playbook.yml, with the following content:
pwd: <password>
---
- name: Configure a wifi connection with 802.1X authentication
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The settings specified in the example playbook include the following:
ieee802_1x
This variable contains the 802.1X-related settings.
eap: tls
Configures the profile to use the certificate-based TLS authentication method for the
Extensible Authentication Protocol (EAP).
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
hosts: managed-node-01.example.com
tasks:
- name: Copy client key for 802.1X authentication
ansible.builtin.copy:
src: "/srv/data/client.key"
dest: "/etc/pki/tls/private/client.key"
mode: 0400
- name: Copy client certificate for 802.1X authentication
ansible.builtin.copy:
src: "/srv/data/client.crt"
dest: "/etc/pki/tls/certs/client.crt"
- name: Copy CA certificate for 802.1X authentication
ansible.builtin.copy:
src: "/srv/data/ca.crt"
dest: "/etc/pki/ca-trust/source/anchors/ca.crt"
- name: Wifi connection profile with dynamic IP address settings and 802.1X
ansible.builtin.import_role:
name: rhel-system-roles.network
vars:
network_connections:
- name: Wifi connection profile with dynamic IP address settings and 802.1X
interface_name: wlp1s0
state: up
type: wireless
autoconnect: yes
ip:
dhcp4: true
auto6: true
wireless:
ssid: "Example-wifi"
key_mgmt: "wpa-eap"
ieee802_1x:
identity: <user_name>
eap: tls
private_key: "/etc/pki/tls/client.key"
private_key_password: "{{ pwd }}"
private_key_password_flags: none
client_cert: "/etc/pki/tls/client.pem"
ca_cert: "/etc/pki/tls/cacert.pem"
domain_suffix_match: "example.com"
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3. Validate the playbook syntax:
$ ansible-playbook --ask-vault-pass --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
4. Run the playbook:
$ ansible-playbook --ask-vault-pass ~/playbook.yml
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
11.8. CONFIGURING A WIFI CONNECTION WITH 802.1X NETWORK
AUTHENTICATION IN AN EXISTING PROFILE BY USING NMCLI
Using the nmcli utility, you can configure the client to authenticate itself to the network. For example,
you can configure Protected Extensible Authentication Protocol (PEAP) authentication with the
Microsoft Challenge-Handshake Authentication Protocol version 2 (MSCHAPv2) in an existing
NetworkManager wifi connection profile named wlp1s0.
Prerequisites
The network must have 802.1X network authentication.
The wifi connection profile exists in NetworkManager and has a valid IP configuration.
If the client is required to verify the certificate of the authenticator, the Certificate Authority
(CA) certificate must be stored in the /etc/pki/ca-trust/source/anchors/ directory.
The wpa_supplicant package is installed.
Procedure
1. Set the wifi security mode to wpa-eap, the Extensible Authentication Protocol (EAP) to peap,
the inner authentication protocol to mschapv2, and the user name:
# nmcli connection modify wlp1s0 wireless-security.key-mgmt wpa-eap 802-1x.eap
peap 802-1x.phase2-auth mschapv2 802-1x.identity user_name
Note that you must set the wireless-security.key-mgmt, 802-1x.eap, 802-1x.phase2-auth,
and 802-1x.identity parameters in a single command.
2. Optional: Store the password in the configuration:
# nmcli connection modify wlp1s0 802-1x.password password
IMPORTANT
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IMPORTANT
By default, NetworkManager stores the password in plain text in the
/etc/sysconfig/network-scripts/keys-connection_name file, which is readable
only by the root user. However, plain text passwords in a configuration file can be
a security risk.
To increase the security, set the 802-1x.password-flags parameter to 0x1. With
this setting, on servers with the GNOME desktop environment or the nm-applet
running, NetworkManager retrieves the password from these services. In other
cases, NetworkManager prompts for the password.
3. If the client needs to verify the certificate of the authenticator, set the 802-1x.ca-cert
parameter in the connection profile to the path of the CA certificate:
# nmcli connection modify wlp1s0 802-1x.ca-cert /etc/pki/ca-
trust/source/anchors/ca.crt
NOTE
For security reasons, clients should validate the certiciate of the authenticator.
4. Activate the connection profile:
# nmcli connection up wlp1s0
Verification
Access resources on the network that require network authentication.
Additional resources
Managing wifi connections
nm-settings(5) man page
nmcli(1) man page
11.9. MANUALLY SETTING THE WIRELESS REGULATORY DOMAIN
On RHEL, a udev rule executes the setregdomain utility to set the wireless regulatory domain. The
utility then provides this information to the kernel.
By default, setregdomain attempts to determine the country code automatically. If this fails, the
wireless regulatory domain setting might be wrong. To work around this problem, you can manually set
the country code.
IMPORTANT
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203
IMPORTANT
Manually setting the regulatory domain disables the automatic detection. Therefore, if
you later use the computer in a different country, the previously configured setting might
no longer be correct. In this case, remove the /etc/sysconfig/regdomain file to switch
back to automatic detection or use this procedure to manually update the regulatory
domain setting again.
Procedure
1. Optional: Display the current regulatory domain settings:
# iw reg get
global
country US: DFS-FCC
...
2. Create the /etc/sysconfig/regdomain file with the following content:
COUNTRY=<country_code>
Set the COUNTRY variable to an ISO 3166-1 alpha2 country code, such as DE for Germany or
US for the United States of America.
3. Set the regulatory domain:
# setregdomain
Verification
Display the regulatory domain settings:
# iw reg get
global
country DE: DFS-ETSI
...
Additional resources
setregdomain(1) man page
iw(8) man page
regulatory.bin(5) man page
ISO 3166 Country Codes
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CHAPTER 12. CONFIGURING RHEL AS A WPA2 OR WPA3
PERSONAL ACCESS POINT
On a host with a wifi device, you can use NetworkManager to configure this host as an access point. Wi-
Fi Protected Access 2 (WPA2) and Wi-Fi Protected Access 3 (WPA3) Personal provide secure
authentication methods, and wireless clients can use a pre-shared key (PSK) to connect to the access
point and use services on the RHEL host and in the network.
When you configure an access point, NetworkManager automatically:
Configures the dnsmasq service to provide DHCP and DNS services for clients
Enables IP forwarding
Adds nftables firewall rules to masquerade traffic from the wifi device and configures IP
forwarding
Prerequisites
The wifi device supports running in access point mode.
The wifi device is not in use.
The host has internet access.
Procedure
1. List the wifi devices to identify the one that should provide the access point:
# nmcli device status | grep wifi
wlp0s20f3 wifi disconnected --
2. Verify that the device supports the access point mode:
# nmcli -f WIFI-PROPERTIES.AP device show wlp0s20f3
WIFI-PROPERTIES.AP: yes
To use a wifi device as an access point, the device must support this feature.
3. Install the dnsmasq and NetworkManager-wifi packages:
# dnf install dnsmasq NetworkManager-wifi
NetworkManager uses the dnsmasq service to provide DHCP and DNS services to clients of
the access point.
4. Create the initial access point configuration:
# nmcli device wifi hotspot ifname wlp0s20f3 con-name Example-Hotspot ssid
Example-Hotspot password "password"
This command creates a connection profile for an access point on the wlp0s20f3 device that
provides WPA2 and WPA3 Personal authentication. The name of the wireless network, the
Service Set Identifier (SSID), is Example-Hotspot and uses the pre-shared key password.
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5. Optional: Configure the access point to support only WPA3:
# nmcli connection modify Example-Hotspot 802-11-wireless-security.key-mgmt sae
6. By default, NetworkManager uses the IP address 10.42.0.1 for the wifi device and assigns IP
addresses from the remaining 10.42.0.0/24 subnet to clients. To configure a different subnet
and IP address, enter:
# nmcli connection modify Example-Hotspot ipv4.addresses 192.0.2.254/24
The IP address you set, in this case 192.0.2.254, is the one that NetworkManager assigns to the
wifi device. Clients will use this IP address as default gateway and DNS server.
7. Activate the connection profile:
# nmcli connection up Example-Hotspot
Verification
1. On the server:
a. Verify that NetworkManager started the dnsmasq service and that the service listens on
port 67 (DHCP) and 53 (DNS):
# ss -tulpn | egrep ":53|:67"
udp UNCONN 0 0 10.42.0.1:53 0.0.0.0:* users:(("dnsmasq",pid=55905,fd=6))
udp UNCONN 0 0 0.0.0.0:67 0.0.0.0:* users:(("dnsmasq",pid=55905,fd=4))
tcp LISTEN 0 32 10.42.0.1:53 0.0.0.0:* users:(("dnsmasq",pid=55905,fd=7))
b. Display the nftables rule set to ensure that NetworkManager enabled forwarding and
masquerading for traffic from the 10.42.0.0/24 subnet:
# nft list ruleset
table ip nm-shared-wlp0s20f3 {
chain nat_postrouting {
type nat hook postrouting priority srcnat; policy accept;
ip saddr 10.42.0.0/24 ip daddr != 10.42.0.0/24 masquerade
}
chain filter_forward {
type filter hook forward priority filter; policy accept;
ip daddr 10.42.0.0/24 oifname "wlp0s20f3" ct state { established, related } accept
ip saddr 10.42.0.0/24 iifname "wlp0s20f3" accept
iifname "wlp0s20f3" oifname "wlp0s20f3" accept
iifname "wlp0s20f3" reject
oifname "wlp0s20f3" reject
}
}
2. On a client with a wifi adapter:
a. Display the list of available networks:
# nmcli device wifi
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IN-USE BSSID SSID MODE CHAN RATE SIGNAL BARS
SECURITY
00:53:00:88:29:04 Example-Hotspot Infra 11 130 Mbit/s 62 ▂▄▆_ WPA3
...
b. Connect to the Example-Hotspot wireless network. See Managing Wi-Fi connections.
c. Ping a host on the remote network or the internet to verify that the connection works:
# ping -c 3 www.redhat.com
Additional resources
nm-settings(5) man page
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CHAPTER 13. USING MACSEC TO ENCRYPT LAYER-2 TRAFFIC
IN THE SAME PHYSICAL NETWORK
You can use MACsec to secure the communication between two devices (point-to-point). For example,
your branch office is connected over a Metro-Ethernet connection with the central office, you can
configure MACsec on the two hosts that connect the offices to increase the security.
Media Access Control security (MACsec) is a layer 2 protocol that secures different traffic types over
the Ethernet links including:
dynamic host configuration protocol (DHCP)
address resolution protocol (ARP)
Internet Protocol version 4 / 6 (IPv4 / IPv6) and
any traffic over IP such as TCP or UDP
MACsec encrypts and authenticates all traffic in LANs, by default with the GCM-AES-128 algorithm, and
uses a pre-shared key to establish the connection between the participant hosts. If you want to change
the pre-shared key, you need to update the NM configuration on all hosts in the network that uses
MACsec.
A MACsec connection uses an Ethernet device, such as an Ethernet network card, VLAN, or tunnel
device, as parent. You can either set an IP configuration only on the MACsec device to communicate
with other hosts only using the encrypted connection, or you can also set an IP configuration on the
parent device. In the latter case, you can use the parent device to communicate with other hosts using an
unencrypted connection and the MACsec device for encrypted connections.
MACsec does not require any special hardware. For example, you can use any switch, except if you want
to encrypt traffic only between a host and a switch. In this scenario, the switch must also support
MACsec.
In other words, there are 2 common methods to configure MACsec;
host to host and
host to switch then switch to other host(s)
IMPORTANT
You can use MACsec only between hosts that are in the same (physical or virtual) LAN.
13.1. CONFIGURING A MACSEC CONNECTION BY USING NMCLI
You can configure Ethernet interfaces to use MACsec using the nmcli utility. For example, you can
create a MACsec connection between two hosts that are connected over Ethernet.
Procedure
1. On the first host on which you configure MACsec:
Create the connectivity association key (CAK) and connectivity-association key name
(CKN) for the pre-shared key:
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a. Create a 16-byte hexadecimal CAK:
# dd if=/dev/urandom count=16 bs=1 2> /dev/null | hexdump -e '1/2 "%04x"'
50b71a8ef0bd5751ea76de6d6c98c03a
b. Create a 32-byte hexadecimal CKN:
# dd if=/dev/urandom count=32 bs=1 2> /dev/null | hexdump -e '1/2 "%04x"'
f2b4297d39da7330910a74abc0449feb45b5c0b9fc23df1430e1898fcf1c4550
2. On both hosts you want to connect over a MACsec connection:
3. Create the MACsec connection:
# nmcli connection add type macsec con-name macsec0 ifname macsec0
connection.autoconnect yes macsec.parent enp1s0 macsec.mode psk macsec.mka-
cak 50b71a8ef0bd5751ea76de6d6c98c03a macsec.mka-ckn
f2b4297d39da7330910a74abc0449feb45b5c0b9fc23df1430e1898fcf1c4550
Use the CAK and CKN generated in the previous step in the macsec.mka-cak and
macsec.mka-ckn parameters. The values must be the same on every host in the MACsec-
protected network.
4. Configure the IP settings on the MACsec connection.
a. Configure the IPv4 settings. For example, to set a static IPv4 address, network mask,
default gateway, and DNS server to the macsec0 connection, enter:
# nmcli connection modify macsec0 ipv4.method manual ipv4.addresses
'192.0.2.1/24' ipv4.gateway '192.0.2.254' ipv4.dns '192.0.2.253'
b. Configure the IPv6 settings. For example, to set a static IPv6 address, network mask,
default gateway, and DNS server to the macsec0 connection, enter:
# nmcli connection modify macsec0 ipv6.method manual ipv6.addresses
'2001:db8:1::1/32' ipv6.gateway '2001:db8:1::fffe' ipv6.dns '2001:db8:1::fffd'
5. Activate the connection:
# nmcli connection up macsec0
Verification
1. Verify that the traffic is encrypted:
# tcpdump -nn -i enp1s0
2. Optional: Display the unencrypted traffic:
# tcpdump -nn -i macsec0
3. Display MACsec statistics:
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# ip macsec show
4. Display individual counters for each type of protection: integrity-only (encrypt off) and
encryption (encrypt on)
# ip -s macsec show
13.2. CONFIGURING A MACSEC CONNECTION USING NMSTATECTL
You can configure Ethernet interfaces to use MACsec through the nmstatectl utility in a declarative
way. For example, in a YAML file, you describe the desired state of your network, which is supposed to
have a MACsec connection between two hosts connected over Ethernet. The nmstatectl utility
interprets the YAML file and deploys persistent and consistent network configuration across the hosts.
Using the MACsec security standard for securing communication at the link layer, also known as layer 2
of the Open Systems Interconnection (OSI) model provides the following notable benefits:
Encryption at layer 2 eliminates the need for encrypting individual services at layer 7. This
reduces the overhead associated with managing a large number of certificates for each
endpoint on each host.
Point-to-point security between directly connected network devices such as routers and
switches.
No changes needed for applications and higher-layer protocols.
Prerequisites
A physical or virtual Ethernet Network Interface Controller (NIC) exists in the server
configuration.
The nmstate package is installed.
Procedure
1. On the first host on which you configure MACsec, create the connectivity association key (CAK)
and connectivity-association key name (CKN) for the pre-shared key:
a. Create a 16-byte hexadecimal CAK:
# dd if=/dev/urandom count=16 bs=1 2> /dev/null | hexdump -e '1/2 "%04x"'
50b71a8ef0bd5751ea76de6d6c98c03a
b. Create a 32-byte hexadecimal CKN:
# dd if=/dev/urandom count=32 bs=1 2> /dev/null | hexdump -e '1/2 "%04x"'
f2b4297d39da7330910a74abc0449feb45b5c0b9fc23df1430e1898fcf1c4550
2. On both hosts that you want to connect over a MACsec connection, complete the following
steps:
a. Create a YAML file, for example create-macsec-connection.yml, with the following
settings:
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---
routes:
config:
- destination: 0.0.0.0/0
next-hop-interface: macsec0
next-hop-address: 192.0.2.2
table-id: 254
- destination: 192.0.2.2/32
next-hop-interface: macsec0
next-hop-address: 0.0.0.0
table-id: 254
dns-resolver:
config:
search:
- example.com
server:
- 192.0.2.200
- 2001:db8:1::ffbb
interfaces:
- name: macsec0
type: macsec
state: up
ipv4:
enabled: true
address:
- ip: 192.0.2.1
prefix-length: 32
ipv6:
enabled: true
address:
- ip: 2001:db8:1::1
prefix-length: 64
macsec:
encrypt: true
base-iface: enp0s1
mka-cak: 50b71a8ef0bd5751ea76de6d6c98c03a
mka-ckn: f2b4297d39da7330910a74abc0449feb45b5c0b9fc23df1430e1898fcf1c4550
port: 0
validation: strict
send-sci: true
b. Use the CAK and CKN generated in the previous step in the mka-cak and mka-ckn
parameters. The values must be the same on every host in the MACsec-protected network.
c. Optional: In the same YAML configuration file, you can also configure the following settings:
A static IPv4 address - 192.0.2.1 with the /32 subnet mask
A static IPv6 address - 2001:db8:1::1 with the /64 subnet mask
An IPv4 default gateway - 192.0.2.2
An IPv4 DNS server - 192.0.2.200
An IPv6 DNS server - 2001:db8:1::ffbb
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A DNS search domain - example.com
3. Apply the settings to the system:
# nmstatectl apply create-macsec-connection.yml
Verification
1. Display the current state in YAML format:
# nmstatectl show macsec0
2. Verify that the traffic is encrypted:
# tcpdump -nn -i enp0s1
3. Optional: Display the unencrypted traffic:
# tcpdump -nn -i macsec0
4. Display MACsec statistics:
# ip macsec show
5. Display individual counters for each type of protection: integrity-only (encrypt off) and
encryption (encrypt on)
# ip -s macsec show
Additional resources
MACsec: a different solution to encrypt network traffic
13.3. ADDITIONAL RESOURCES
MACsec: a different solution to encrypt network traffic blog.
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CHAPTER 14. GETTING STARTED WITH IPVLAN
IPVLAN is a driver for a virtual network device that can be used in container environment to access the
host network. IPVLAN exposes a single MAC address to the external network regardless the number of
IPVLAN device created inside the host network. This means that a user can have multiple IPVLAN
devices in multiple containers and the corresponding switch reads a single MAC address. IPVLAN driver
is useful when the local switch imposes constraints on the total number of MAC addresses that it can
manage.
14.1. IPVLAN MODES
The following modes are available for IPVLAN:
L2 mode
In IPVLAN L2 mode, virtual devices receive and respond to address resolution protocol (ARP)
requests. The netfilter framework runs only inside the container that owns the virtual device. No
netfilter chains are executed in the default namespace on the containerized traffic. Using L2
mode provides good performance, but less control on the network traffic.
L3 mode
In L3 mode, virtual devices process only L3 traffic and above. Virtual devices do not respond to
ARP request and users must configure the neighbour entries for the IPVLAN IP addresses on
the relevant peers manually. The egress traffic of a relevant container is landed on the netfilter
POSTROUTING and OUTPUT chains in the default namespace while the ingress traffic is
threaded in the same way as L2 mode. Using L3 mode provides good control but decreases the
network traffic performance.
L3S mode
In L3S mode, virtual devices process the same way as in L3 mode, except that both egress and
ingress traffics of a relevant container are landed on netfilter chain in the default namespace.
L3S mode behaves in a similar way to L3 mode but provides greater control of the network.
NOTE
The IPVLAN virtual device does not receive broadcast and multicast traffic in case of L3
and L3S modes.
14.2. COMPARISON OF IPVLAN AND MACVLAN
The following table shows the major differences between MACVLAN and IPVLAN:
MACVLAN IPVLAN
Uses MAC address for each MACVLAN device.
Note that, if a switch reaches the maximum number
of MAC addresses it can store in its MAC table,
connectivity can be lost.
Uses single MAC address which does not limit the
number of IPVLAN devices.
Netfilter rules for a global namespace cannot affect
traffic to or from a MACVLAN device in a child
namespace.
It is possible to control traffic to or from a IPVLAN
device in L3 mode and L3S mode.
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Both IPVLAN and MACVLAN do not require any level of encapsulation.
14.3. CREATING AND CONFIGURING THE IPVLAN DEVICE USING
IPROUTE2
This procedure shows how to set up the IPVLAN device using iproute2.
Procedure
1. To create an IPVLAN device, enter the following command:
# ip link add link real_NIC_device name IPVLAN_device type ipvlan mode l2
Note that network interface controller (NIC) is a hardware component which connects a
computer to a network.
Example 14.1. Creating an IPVLAN device
# ip link add link enp0s31f6 name my_ipvlan type ipvlan mode l2
# ip link
47: my_ipvlan@enp0s31f6: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state
DOWN mode DEFAULT group default qlen 1000 link/ether e8:6a:6e:8a:a2:44 brd
ff:ff:ff:ff:ff:ff
2. To assign an IPv4 or IPv6 address to the interface, enter the following command:
# ip addr add dev IPVLAN_device IP_address/subnet_mask_prefix
3. In case of configuring an IPVLAN device in L3 mode or L3S mode, make the following setups:
a. Configure the neighbor setup for the remote peer on the remote host:
# ip neigh add dev peer_device IPVLAN_device_IP_address lladdr MAC_address
where MAC_address is the MAC address of the real NIC on which an IPVLAN device is based
on.
b. Configure an IPVLAN device for L3 mode with the following command:
# ip route add dev <real_NIC_device> <peer_IP_address/32>
For L3S mode:
# ip route add dev real_NIC_device peer_IP_address/32
where IP-address represents the address of the remote peer.
4. To set an IPVLAN device active, enter the following command:
# ip link set dev IPVLAN_device up
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5. To check if the IPVLAN device is active, execute the following command on the remote host:
# ping IP_address
where the IP_address uses the IP address of the IPVLAN device.
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CHAPTER 15. CONFIGURING NETWORKMANAGER TO
IGNORE CERTAIN DEVICES
By default, NetworkManager manages all devices. To ignore certain devices, you can configure
NetworkManager by setting as unmanaged.
15.1. CONFIGURING THE LOOPBACK INTERFACE BY USING NMCLI
By default, NetworkManager does not manage the loopback (lo) interface. After creating a connection
profile for the lo interface, you can configure this device by using NetworkManager. Some of the
examples are as follows:
Assign additional IP addresses to the lo interface
Define DNS addresses
Change the Maximum Transmission Unit (MTU) size of the lo interface
Procedure
1. Create a new connection of type loopback:
# nmcli connection add con-name example-loopback type loopback
2. Configure custom connection settings, for example:
a. To assign an additional IP address to the interface, enter:
# nmcli connection modify example-loopback +ipv4.addresses 192.0.2.1/24
NOTE
NetworkManager manages the lo interface by always assigning the IP
addresses 127.0.0.1 and ::1 that are persistent across the reboots. You can
not override 127.0.0.1 and ::1. However, you can assign additional IP
addresses to the interface.
b. To set a custom Maximum Transmission Unit (MTU), enter:
# nmcli con mod example-loopback loopback.mtu 16384
c. To set an IP address to your DNS server, enter:
# nmcli connection modify example-loopback ipv4.dns 192.0.2.0
If you set a DNS server in the loopback connection profile, this entry is always available in
the /etc/resolv.conf file. The DNS server entry remains independent of whether or not the
host roams between different networks.
3. Activate the connection:
# nmcli connection up example-loopback
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Verification
1. Display the settings of the lo interface:
# ip address show lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16384 qdisc noqueue state UNKNOWN group
default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft
forever preferred_lft forever inet 192.0.2.1/24 brd 192.0.2.255 scope global lo valid_lft forever
preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2. Verify the DNS address:
# cat /etc/resolv.conf
...
nameserver 192.0.2.0
...
15.2. PERMANENTLY CONFIGURING A DEVICE AS UNMANAGED IN
NETWORKMANAGER
You can permanently configure devices as unmanaged based on several criteria, such as the interface
name, MAC address, or device type.
To temporarily configure network devices as unmanaged, see Temporarily configuring a device as
unmanaged in NetworkManager.
Procedure
1. Optional: Display the list of devices to identify the device or MAC address you want to set as
unmanaged:
# ip link show
...
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
mode DEFAULT group default qlen 1000
link/ether 52:54:00:74:79:56 brd ff:ff:ff:ff:ff:ff
...
2. Create the /etc/NetworkManager/conf.d/99-unmanaged-devices.conf file with the following
content:
To configure a specific interface as unmanaged, add:
[keyfile]
unmanaged-devices=interface-name:enp1s0
To configure a device with a specific MAC address as unmanaged, add:
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217
[keyfile]
unmanaged-devices=mac:52:54:00:74:79:56
To configure all devices of a specific type as unmanaged, add:
[keyfile]
unmanaged-devices=type:ethernet
To set multiple devices as unmanaged, separate the entries in the unmanaged-devices
parameter with a semicolon, for example:
[keyfile]
unmanaged-devices=interface-name:enp1s0;interface-name:enp7s0
3. Reload the NetworkManager service:
# systemctl reload NetworkManager
Verification
Display the list of devices:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp1s0 ethernet unmanaged --
...
The unmanaged state next to the enp1s0 device indicates that NetworkManager does not
manage this device.
Troubleshooting
If the device is not shown as unmanaged, display the NetworkManager configuration:
# NetworkManager --print-config
...
[keyfile]
unmanaged-devices=interface-name:enp1s0
...
If the output does not match the settings that you configured, ensure that no configuration file
with a higher priority overrides your settings. For details about how NetworkManager merges
multiple configuration files, see the NetworkManager.conf(5) man page.
15.3. TEMPORARILY CONFIGURING A DEVICE AS UNMANAGED IN
NETWORKMANAGER
You can temporarily configure devices as unmanaged.
Use this method, for example, for testing purposes. To permanently configure network devices as
unmanaged, see Permanently configuring a device as unmanaged in NetworkManager .
Procedure
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Procedure
1. Optional: Display the list of devices to identify the device you want to set as unmanaged:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp1s0 ethernet disconnected --
...
2. Set the enp1s0 device to the unmanaged state:
# nmcli device set enp1s0 managed no
Verification
Display the list of devices:
# nmcli device status
DEVICE TYPE STATE CONNECTION
enp1s0 ethernet unmanaged --
...
The unmanaged state next to the enp1s0 device indicates that NetworkManager does not
manage this device.
Additional resources
NetworkManager.conf(5) man page
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219
CHAPTER 16. CREATING A DUMMY INTERFACE
As a Red Hat Enterprise Linux user, you can create and use dummy network interfaces for debugging
and testing purposes. A dummy interface provides a device to route packets without actually
transmitting them. It enables you to create additional loopback-like devices managed by
NetworkManager and makes an inactive SLIP (Serial Line Internet Protocol) address look like a real
address for local programs.
16.1. CREATING A DUMMY INTERFACE WITH BOTH AN IPV4 AND IPV6
ADDRESS BY USING NMCLI
You can create a dummy interface with various settings, such as IPv4 and IPv6 addresses. After creating
the interface, NetworkManager automatically assigns it to the default public firewalld zone.
Procedure
Create a dummy interface named dummy0 with static IPv4 and IPv6 addresses:
# nmcli connection add type dummy ifname dummy0 ipv4.method manual
ipv4.addresses 192.0.2.1/24 ipv6.method manual ipv6.addresses 2001:db8:2::1/64
NOTE
To configure a dummy interface without IPv4 and IPv6 addresses, set both the
ipv4.method and ipv6.method parameters to disabled. Otherwise, IP auto-
configuration fails, and NetworkManager deactivates the connection and
removes the device.
Verification
List the connection profiles:
# nmcli connection show
NAME UUID TYPE DEVICE
dummy-dummy0 aaf6eb56-73e5-4746-9037-eed42caa8a65 dummy dummy0
Additional resources
nm-settings(5) man page
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CHAPTER 17. USING NETWORKMANAGER TO DISABLE IPV6
FOR A SPECIFIC CONNECTION
On a system that uses NetworkManager to manage network interfaces, you can disable the IPv6
protocol if the network only uses IPv4. If you disable IPv6, NetworkManager automatically sets the
corresponding sysctl values in the Kernel.
NOTE
If disabling IPv6 using kernel tunables or kernel boot parameters, additional consideration
must be given to system configuration. For more information, see the How do I disable or
enable the IPv6 protocol in RHEL? article.
17.1. DISABLING IPV6 ON A CONNECTION USING NMCLI
You can use the nmcli utility to disable the IPv6 protocol on the command line.
Prerequisites
The system uses NetworkManager to manage network interfaces.
Procedure
1. Optional: Display the list of network connections:
# nmcli connection show
NAME UUID TYPE DEVICE
Example 7a7e0151-9c18-4e6f-89ee-65bb2d64d365 ethernet enp1s0
...
2. Set the ipv6.method parameter of the connection to disabled:
# nmcli connection modify Example ipv6.method "disabled"
3. Restart the network connection:
# nmcli connection up Example
Verification
1. Display the IP settings of the device:
# ip address show enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
group default qlen 1000
link/ether 52:54:00:6b:74:be brd ff:ff:ff:ff:ff:ff
inet 192.0.2.1/24 brd 192.10.2.255 scope global noprefixroute enp1s0
valid_lft forever preferred_lft forever
If no inet6 entry is displayed, IPv6 is disabled on the device.
2. Verify that the /proc/sys/net/ipv6/conf/enp1s0/disable_ipv6 file now contains the value 1:
CHAPTER 17. USING NETWORKMANAGER TO DISABLE IPV6 FOR A SPECIFIC CONNECTION
221
# cat /proc/sys/net/ipv6/conf/enp1s0/disable_ipv6
1
The value 1 means that IPv6 is disabled for the device.
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CHAPTER 18. CHANGING A HOSTNAME
The hostname of a system is the name on the system itself. You can set the name when you install
RHEL, and you can change it afterwards.
18.1. CHANGING A HOSTNAME BY USING NMCLI
You can use the nmcli utility to update the system hostname. Note that other utilities might use a
different term, such as static or persistent hostname.
Procedure
1. Optional: Display the current hostname setting:
# nmcli general hostname
old-hostname.example.com
2. Set the new hostname:
# nmcli general hostname new-hostname.example.com
3. NetworkManager automatically restarts the systemd-hostnamed to activate the new name.
For the changes to take effect, reboot the host:
# reboot
Alternatively, if you know which services use the hostname:
a. Restart all services that only read the hostname when the service starts:
# systemctl restart <service_name>
b. Active shell users must re-login for the changes to take effect.
Verification
Display the hostname:
# nmcli general hostname
new-hostname.example.com
18.2. CHANGING A HOSTNAME BY USING HOSTNAMECTL
You can use the hostnamectl utility to update the hostname. By default, this utility sets the following
hostname types:
Static hostname: Stored in the /etc/hostname file. Typically, services use this name as the
hostname.
Pretty hostname: A descriptive name, such as Proxy server in data center A.
Transient hostname: A fall-back value that is typically received from the network configuration.
CHAPTER 18. CHANGING A HOSTNAME
223
Procedure
1. Optional: Display the current hostname setting:
# hostnamectl status --static
old-hostname.example.com
2. Set the new hostname:
# hostnamectl set-hostname new-hostname.example.com
This command sets the static, pretty, and transient hostname to the new value. To set only a
specific type, pass the --static, --pretty, or --transient option to the command.
3. The hostnamectl utility automatically restarts the systemd-hostnamed to activate the new
name. For the changes to take effect, reboot the host:
# reboot
Alternatively, if you know which services use the hostname:
a. Restart all services that only read the hostname when the service starts:
# systemctl restart <service_name>
b. Active shell users must re-login for the changes to take effect.
Verification
Display the hostname:
# hostnamectl status --static
new-hostname.example.com
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CHAPTER 19. CONFIGURING NETWORKMANAGER DHCP
SETTINGS
NetworkManager provides different configuration options related to DHCP. For example, you can
configure NetworkManager to use the build-in DHCP client (default) or an external client, and you can
influence DHCP settings of individual profiles.
19.1. CHANGING THE DHCP CLIENT OF NETWORKMANAGER
By default, NetworkManager uses its internal DHCP client. However, if you require a DHCP client with
features that the built-in client does not provide, you can alternatively configure NetworkManager to
use dhclient.
Note that RHEL does not provide dhcpcd and, therefore, NetworkManager can not use this client.
Procedure
1. Create the /etc/NetworkManager/conf.d/dhcp-client.conf file with the following content:
[main]
dhcp=dhclient
You can set the dhcp parameter to internal (default) or dhclient.
2. If you set the dhcp parameter to dhclient, install the dhcp-client package:
# dnf install dhcp-client
3. Restart NetworkManager:
# systemctl restart NetworkManager
Note that the restart temporarily interrupts all network connections.
Verification
Search in the /var/log/messages log file for an entry similar to the following:
Apr 26 09:54:19 server NetworkManager[27748]: <info> [1650959659.8483] dhcp-init: Using
DHCP client 'dhclient'
This log entry confirms that NetworkManager uses dhclient as DHCP client.
Additional resources
NetworkManager.conf(5) man page
19.2. CONFIGURING THE DHCP BEHAVIOR OF A NETWORKMANAGER
CONNECTION
A Dynamic Host Configuration Protocol (DHCP) client requests the dynamic IP address and
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225
A Dynamic Host Configuration Protocol (DHCP) client requests the dynamic IP address and
corresponding configuration information from a DHCP server each time a client connects to the
network.
When you configured a connection to retrieve an IP address from a DHCP server, the NetworkManager
requests an IP address from a DHCP server. By default, the client waits 45 seconds for this request to be
completed. When a DHCP connection is started, a dhcp client requests an IP address from a DHCP
server.
Prerequisites
A connection that uses DHCP is configured on the host.
Procedure
1. Set the ipv4.dhcp-timeout and ipv6.dhcp-timeout properties. For example, to set both
options to 30 seconds, enter:
# nmcli connection modify <connection_name> ipv4.dhcp-timeout 30 ipv6.dhcp-
timeout 30
Alternatively, set the parameters to infinity to configure that NetworkManager does not stop
trying to request and renew an IP address until it is successful.
2. Optional: Configure the behavior if NetworkManager does not receive an IPv4 address before
the timeout:
# nmcli connection modify <connection_name> ipv4.may-fail <value>
If you set the ipv4.may-fail option to:
yes, the status of the connection depends on the IPv6 configuration:
If the IPv6 configuration is enabled and successful, NetworkManager activates the IPv6
connection and no longer tries to activate the IPv4 connection.
If the IPv6 configuration is disabled or not configured, the connection fails.
no, the connection is deactivated. In this case:
If the autoconnect property of the connection is enabled, NetworkManager retries to
activate the connection as many times as set in the autoconnect-retries property. The
default is 4.
If the connection still cannot acquire a DHCP address, auto-activation fails. Note that
after 5 minutes, the auto-connection process starts again to acquire an IP address from
the DHCP server.
3. Optional: Configure the behavior if NetworkManager does not receive an IPv6 address before
the timeout:
# nmcli connection modify <connection_name> ipv6.may-fail <value>
Additional resources
nm-settings(5) man page
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CHAPTER 20. RUNNING DHCLIENT EXIT HOOKS USING
NETWORKMANAGER A DISPATCHER SCRIPT
You can use a NetworkManager dispatcher script to execute dhclient exit hooks.
20.1. THE CONCEPT OF NETWORKMANAGER DISPATCHER SCRIPTS
The NetworkManager-dispatcher service executes user-provided scripts in alphabetical order when
network events happen. These scripts are typically shell scripts, but can be any executable script or
application. You can use dispatcher scripts, for example, to adjust network-related settings that you
cannot manage with NetworkManager.
You can store dispatcher scripts in the following directories:
/etc/NetworkManager/dispatcher.d/: The general location for dispatcher scripts the root user
can edit.
/usr/lib/NetworkManager/dispatcher.d/: For pre-deployed immutable dispatcher scripts.
For security reasons, the NetworkManager-dispatcher service executes scripts only if the following
conditions met:
The script is owned by the root user.
The script is only readable and writable by root.
The setuid bit is not set on the script.
The NetworkManager-dispatcher service runs each script with two arguments:
1. The interface name of the device the operation happened on.
2. The action, such as up, when the interface has been activated.
The Dispatcher scripts section in the NetworkManager(8) man page provides an overview of actions
and environment variables you can use in scripts.
The NetworkManager-dispatcher service runs one script at a time, but asynchronously from the main
NetworkManager process. Note that, if a script is queued, the service will always run it, even if a later
event makes it obsolete. However, the NetworkManager-dispatcher service runs scripts that are
symbolic links referring to files in /etc/NetworkManager/dispatcher.d/no-wait.d/ immediately, without
waiting for the termination of previous scripts, and in parallel.
Additional resources
NetworkManager(8) man page
20.2. CREATING A NETWORKMANAGER DISPATCHER SCRIPT THAT
RUNS DHCLIENT EXIT HOOKS
When a DHCP server assigns or updates an IPv4 address, NetworkManager can run a dispatcher script
stored in the /etc/dhcp/dhclient-exit-hooks.d/ directory. This dispatcher script can then, for example,
run dhclient exit hooks.
Prerequisites
CHAPTER 20. RUNNING DHCLIENT EXIT HOOKS USING NETWORKMANAGER A DISPATCHER SCRIPT
227
Prerequisites
The dhclient exit hooks are stored in the /etc/dhcp/dhclient-exit-hooks.d/ directory.
Procedure
1. Create the /etc/NetworkManager/dispatcher.d/12-dhclient-down file with the following
content:
2. Set the root user as owner of the file:
# chown root:root /etc/NetworkManager/dispatcher.d/12-dhclient-down
3. Set the permissions so that only the root user can execute it:
# chmod 0700 /etc/NetworkManager/dispatcher.d/12-dhclient-down
4. Restore the SELinux context:
# restorecon /etc/NetworkManager/dispatcher.d/12-dhclient-down
Additional resources
NetworkManager(8) man page
#!/bin/bash
# Run dhclient.exit-hooks.d scripts
if [ -n "$DHCP4_DHCP_LEASE_TIME" ] ; then
if [ "$2" = "dhcp4-change" ] || [ "$2" = "up" ] ; then
if [ -d /etc/dhcp/dhclient-exit-hooks.d ] ; then
for f in /etc/dhcp/dhclient-exit-hooks.d/*.sh ; do
if [ -x "${f}" ]; then
. "${f}"
fi
done
fi
fi
fi
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CHAPTER 21. MANUALLY CONFIGURING THE
/ETC/RESOLV.CONF FILE
By default, NetworkManager dynamically updates the /etc/resolv.conf file with the DNS settings from
active NetworkManager connection profiles. However, you can disable this behavior and manually
configure DNS settings in /etc/resolv.conf.
NOTE
Alternatively, if you require a specific order of DNS servers in /etc/resolv.conf, see
Configuring the order of DNS servers .
21.1. DISABLING DNS PROCESSING IN THE NETWORKMANAGER
CONFIGURATION
By default, NetworkManager manages DNS settings in the /etc/resolv.conf file, and you can configure
the order of DNS servers. Alternatively, you can disable DNS processing in NetworkManager if you
prefer to manually configure DNS settings in /etc/resolv.conf.
Procedure
1. As the root user, create the /etc/NetworkManager/conf.d/90-dns-none.conf file with the
following content by using a text editor:
[main]
dns=none
2. Reload the NetworkManager service:
# systemctl reload NetworkManager
NOTE
After you reload the service, NetworkManager no longer updates the
/etc/resolv.conf file. However, the last contents of the file are preserved.
3. Optional: Remove the Generated by NetworkManager comment from /etc/resolv.conf to
avoid confusion.
Verification
1. Edit the /etc/resolv.conf file and manually update the configuration.
2. Reload the NetworkManager service:
# systemctl reload NetworkManager
3. Display the /etc/resolv.conf file:
# cat /etc/resolv.conf
If you successfully disabled DNS processing, NetworkManager did not override the manually
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229
If you successfully disabled DNS processing, NetworkManager did not override the manually
configured settings.
Troubleshooting
Display the NetworkManager configuration to ensure that no other configuration file with a
higher priority overrode the setting:
# NetworkManager --print-config
...
dns=none
...
Additional resources
NetworkManager.conf(5) man page
Configuring the order of DNS servers using NetworkManager
21.2. REPLACING /ETC/RESOLV.CONF WITH A SYMBOLIC LINK TO
MANUALLY CONFIGURE DNS SETTINGS
By default, NetworkManager manages DNS settings in the /etc/resolv.conf file, and you can configure
the order of DNS servers. Alternatively, you can disable DNS processing in NetworkManager if you
prefer to manually configure DNS settings in /etc/resolv.conf. For example, NetworkManager does not
automatically update the DNS configuration if /etc/resolv.conf is a symbolic link.
Prerequisites
The NetworkManager rc-manager configuration option is not set to file. To verify, use the
NetworkManager --print-config command.
Procedure
1. Create a file, such as /etc/resolv.conf.manually-configured, and add the DNS configuration for
your environment to it. Use the same parameters and syntax as in the original /etc/resolv.conf.
2. Remove the /etc/resolv.conf file:
# rm /etc/resolv.conf
3. Create a symbolic link named /etc/resolv.conf that refers to /etc/resolv.conf.manually-
configured:
# ln -s /etc/resolv.conf.manually-configured /etc/resolv.conf
Additional resources
resolv.conf(5) man page
NetworkManager.conf(5) man page
Configuring the order of DNS servers using NetworkManager
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CHAPTER 22. CONFIGURING THE ORDER OF DNS SERVERS
Most applications use the getaddrinfo() function of the glibc library to resolve DNS requests. By
default, glibc sends all DNS requests to the first DNS server specified in the /etc/resolv.conf file. If this
server does not reply, RHEL uses the next server in this file. NetworkManager enables you to influence
the order of DNS servers in etc/resolv.conf.
22.1. HOW NETWORKMANAGER ORDERS DNS SERVERS IN
/ETC/RESOLV.CONF
NetworkManager orders DNS servers in the /etc/resolv.conf file based on the following rules:
If only one connection profile exists, NetworkManager uses the order of IPv4 and IPv6 DNS
server specified in that connection.
If multiple connection profiles are activated, NetworkManager orders DNS servers based on a
DNS priority value. If you set DNS priorities, the behavior of NetworkManager depends on the
value set in the dns parameter. You can set this parameter in the [main] section in the
/etc/NetworkManager/NetworkManager.conf file:
dns=default or if the dns parameter is not set:
NetworkManager orders the DNS servers from different connections based on the
ipv4.dns-priority and ipv6.dns-priority parameter in each connection.
If you set no value or you set ipv4.dns-priority and ipv6.dns-priority to 0,
NetworkManager uses the global default value. See Default values of DNS priority
parameters.
dns=dnsmasq or dns=systemd-resolved:
When you use one of these settings, NetworkManager sets either 127.0.0.1 for dnsmasq or
127.0.0.53 as nameserver entry in the /etc/resolv.conf file.
Both the dnsmasq and systemd-resolved services forward queries for the search domain
set in a NetworkManager connection to the DNS server specified in that connection, and
forwardes queries to other domains to the connection with the default route. When multiple
connections have the same search domain set, dnsmasq and systemd-resolved forward
queries for this domain to the DNS server set in the connection with the lowest priority
value.
Default values of DNS priority parameters
NetworkManager uses the following default values for connections:
50 for VPN connections
100 for other connections
Valid DNS priority values:
You can set both the global default and connection-specific ipv4.dns-priority and ipv6.dns-priority
parameters to a value between -2147483647 and 2147483647.
A lower value has a higher priority.
Negative values have the special effect of excluding other configurations with a greater value.
For example, if at least one connection with a negative priority value exists, NetworkManager
uses only the DNS servers specified in the connection profile with the lowest priority.
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If multiple connections have the same DNS priority, NetworkManager prioritizes the DNS in the
following order:
a. VPN connections
b. Connection with an active default route. The active default route is the default route with
the lowest metric.
Additional resources
nm-settings(5) man page
Using different DNS servers for different domains
22.2. SETTING A NETWORKMANAGER-WIDE DEFAULT DNS SERVER
PRIORITY VALUE
NetworkManager uses the following DNS priority default values for connections:
50 for VPN connections
100 for other connections
You can override these system-wide defaults with a custom default value for IPv4 and IPv6
connections.
Procedure
1. Edit the /etc/NetworkManager/NetworkManager.conf file:
a. Add the [connection] section, if it does not exist:
[connection]
b. Add the custom default values to the [connection] section. For example, to set the new
default for both IPv4 and IPv6 to 200, add:
ipv4.dns-priority=200
ipv6.dns-priority=200
You can set the parameters to a value between -2147483647 and 2147483647. Note that
setting the parameters to 0 enables the built-in defaults ( 50 for VPN connections and 100
for other connections).
2. Reload the NetworkManager service:
# systemctl reload NetworkManager
Additional resources
NetworkManager.conf(5) man page
22.3. SETTING THE DNS PRIORITY OF A NETWORKMANAGER
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22.3. SETTING THE DNS PRIORITY OF A NETWORKMANAGER
CONNECTION
If you require a specific order of DNS servers you can set priority values in connection profiles.
NetworkManager uses these values to order the servers when the service creates or updates the
/etc/resolv.conf file.
Note that setting DNS priorities makes only sense if you have multiple connections with different DNS
servers configured. If you have only one connection with multiple DNS servers configured, manually set
the DNS servers in the preferred order in the connection profile.
Prerequisites
The system has multiple NetworkManager connections configured.
The system either has no dns parameter set in the
/etc/NetworkManager/NetworkManager.conf file or the parameter is set to default.
Procedure
1. Optional: Display the available connections:
# nmcli connection show
NAME UUID TYPE DEVICE
Example_con_1 d17ee488-4665-4de2-b28a-48befab0cd43 ethernet enp1s0
Example_con_2 916e4f67-7145-3ffa-9f7b-e7cada8f6bf7 ethernet enp7s0
...
2. Set the ipv4.dns-priority and ipv6.dns-priority parameters. For example, to set both
parameters to 10, enter:
# nmcli connection modify <connection_name> ipv4.dns-priority 10 ipv6.dns-priority
10
3. Optional: Repeat the previous step for other connections.
4. Re-activate the connection you updated:
# nmcli connection up <connection_name>
Verification
Display the contents of the /etc/resolv.conf file to verify that the DNS server order is correct:
# cat /etc/resolv.conf
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233
CHAPTER 23. USING DIFFERENT DNS SERVERS FOR
DIFFERENT DOMAINS
By default, Red Hat Enterprise Linux (RHEL) sends all DNS requests to the first DNS server specified in
the /etc/resolv.conf file. If this server does not reply, RHEL uses the next server in this file. In
environments where one DNS server cannot resolve all domains, administrators can configure RHEL to
send DNS requests for a specific domain to a selected DNS server.
For example, you connect a server to a Virtual Private Network (VPN), and hosts in the VPN use the
example.com domain. In this case, you can configure RHEL to process DNS queries in the following
way:
Send only DNS requests for example.com to the DNS server in the VPN network.
Send all other requests to the DNS server that is configured in the connection profile with the
default gateway.
23.1. USING DNSMASQ IN NETWORKMANAGER TO SEND DNS
REQUESTS FOR A SPECIFIC DOMAIN TO A SELECTED DNS SERVER
You can configure NetworkManager to start an instance of dnsmasq. This DNS caching server then
listens on port 53 on the loopback device. Consequently, this service is only reachable from the local
system and not from the network.
With this configuration, NetworkManager adds the nameserver 127.0.0.1 entry to the /etc/resolv.conf
file, and dnsmasq dynamically routes DNS requests to the corresponding DNS servers specified in the
NetworkManager connection profiles.
Prerequisites
The system has multiple NetworkManager connections configured.
A DNS server and search domain are configured in the NetworkManager connection profile that
is responsible for resolving a specific domain.
For example, to ensure that the DNS server specified in a VPN connection resolves queries for
the example.com domain, the VPN connection profile must contain the following settings:
A DNS server that can resolve example.com
A search domain set to example.com in the ipv4.dns-search and ipv6.dns-search
parameters
The dnsmasq service is not running or configured to listen on a different interface then
localhost.
Procedure
1. Install the dnsmasq package:
# dnf install dnsmasq
2. Edit the /etc/NetworkManager/NetworkManager.conf file, and set the following entry in the
[main] section:
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dns=dnsmasq
3. Reload the NetworkManager service:
# systemctl reload NetworkManager
Verification
1. Search in the systemd journal of the NetworkManager unit for which domains the service uses
a different DNS server:
# journalctl -xeu NetworkManager
...
Jun 02 13:30:17 <client_hostname>_ dnsmasq[5298]: using nameserver 198.51.100.7#53
for domain example.com
...
2. Use the tcpdump packet sniffer to verify the correct route of DNS requests:
a. Install the tcpdump package:
# dnf install tcpdump
b. On one terminal, start tcpdump to capture DNS traffic on all interfaces:
# tcpdump -i any port 53
c. On a different terminal, resolve host names for a domain for which an exception exists and
another domain, for example:
# host -t A www.example.com
# host -t A www.redhat.com
d. Verify in the tcpdump output that Red Hat Enterprise Linux sends only DNS queries for the
example.com domain to the designated DNS server and through the corresponding
interface:
...
13:52:42.234533 tun0 Out IP server.43534 > 198.51.100.7.domain: 50121+ A?
www.example.com. (33)
...
13:52:57.753235 enp1s0 Out IP server.40864 > 192.0.2.1.domain: 6906+ A?
www.redhat.com. (33)
...
Red Hat Enterprise Linux sends the DNS query for www.example.com to the DNS server
on 198.51.100.7 and the query for www.redhat.com to 192.0.2.1.
Troubleshooting
1. Verify that the nameserver entry in the /etc/resolv.conf file refers to 127.0.0.1:
CHAPTER 23. USING DIFFERENT DNS SERVERS FOR DIFFERENT DOMAINS
235
# cat /etc/resolv.conf
nameserver 127.0.0.1
If the entry is missing, check the dns parameter in the
/etc/NetworkManager/NetworkManager.conf file.
2. Verify that the dnsmasq service listens on port 53 on the loopback device:
# ss -tulpn | grep "127.0.0.1:53"
udp UNCONN 0 0 127.0.0.1:53 0.0.0.0:* users:(("dnsmasq",pid=7340,fd=18))
tcp LISTEN 0 32 127.0.0.1:53 0.0.0.0:* users:(("dnsmasq",pid=7340,fd=19))
If the service does not listen on 127.0.0.1:53, check the journal entries of the NetworkManager
unit:
# journalctl -u NetworkManager
23.2. USING SYSTEMD-RESOLVED IN NETWORKMANAGER TO SEND
DNS REQUESTS FOR A SPECIFIC DOMAIN TO A SELECTED DNS
SERVER
You can configure NetworkManager to start an instance of systemd-resolved. This DNS stub resolver
then listens on port 53 on IP address 127.0.0.53. Consequently, this stub resolver is only reachable from
the local system and not from the network.
With this configuration, NetworkManager adds the nameserver 127.0.0.53 entry to the
/etc/resolv.conf file, and systemd-resolved dynamically routes DNS requests to the corresponding
DNS servers specified in the NetworkManager connection profiles.
IMPORTANT
The systemd-resolved service is provided as a Technology Preview only. Technology
Preview features are not supported with Red Hat production Service Level Agreements
(SLAs), might not be functionally complete, and Red Hat does not recommend using
them for production. These previews provide early access to upcoming product features,
enabling customers to test functionality and provide feedback during the development
process.
See Technology Preview Features Support Scope on the Red Hat Customer Portal for
information about the support scope for Technology Preview features.
For a supported solution, see Using dnsmasq in NetworkManager to send DNS requests
for a specific domain to a selected DNS server.
Prerequisites
The system has multiple NetworkManager connections configured.
A DNS server and search domain are configured in the NetworkManager connection profile that
is responsible for resolving a specific domain.
For example, to ensure that the DNS server specified in a VPN connection resolves queries for
the example.com domain, the VPN connection profile must contain the following settings:
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A DNS server that can resolve example.com
A search domain set to example.com in the ipv4.dns-search and ipv6.dns-search
parameters
Procedure
1. Enable and start the systemd-resolved service:
# systemctl --now enable systemd-resolved
2. Edit the /etc/NetworkManager/NetworkManager.conf file, and set the following entry in the
[main] section:
dns=systemd-resolved
3. Reload the NetworkManager service:
# systemctl reload NetworkManager
Verification
1. Display the DNS servers systemd-resolved uses and for which domains the service uses a
different DNS server:
# resolvectl
...
Link 2 (enp1s0)
Current Scopes: DNS
Protocols: +DefaultRoute ...
Current DNS Server: 192.0.2.1
DNS Servers: 192.0.2.1
Link 3 (tun0)
Current Scopes: DNS
Protocols: -DefaultRoute ...
Current DNS Server: 198.51.100.7
DNS Servers: 198.51.100.7 203.0.113.19
DNS Domain: example.com
The output confirms that systemd-resolved uses different DNS servers for the example.com
domain.
2. Use the tcpdump packet sniffer to verify the correct route of DNS requests:
a. Install the tcpdump package:
# dnf install tcpdump
b. On one terminal, start tcpdump to capture DNS traffic on all interfaces:
# tcpdump -i any port 53
c. On a different terminal, resolve host names for a domain for which an exception exists and
CHAPTER 23. USING DIFFERENT DNS SERVERS FOR DIFFERENT DOMAINS
237
c. On a different terminal, resolve host names for a domain for which an exception exists and
another domain, for example:
# host -t A www.example.com
# host -t A www.redhat.com
d. Verify in the tcpdump output that Red Hat Enterprise Linux sends only DNS queries for the
example.com domain to the designated DNS server and through the corresponding
interface:
...
13:52:42.234533 tun0 Out IP server.43534 > 198.51.100.7.domain: 50121+ A?
www.example.com. (33)
...
13:52:57.753235 enp1s0 Out IP server.40864 > 192.0.2.1.domain: 6906+ A?
www.redhat.com. (33)
...
Red Hat Enterprise Linux sends the DNS query for www.example.com to the DNS server
on 198.51.100.7 and the query for www.redhat.com to 192.0.2.1.
Troubleshooting
1. Verify that the nameserver entry in the /etc/resolv.conf file refers to 127.0.0.53:
# cat /etc/resolv.conf
nameserver 127.0.0.53
If the entry is missing, check the dns parameter in the
/etc/NetworkManager/NetworkManager.conf file.
2. Verify that the systemd-resolved service listens on port 53 on the local IP address 127.0.0.53:
# ss -tulpn | grep "127.0.0.53"
udp UNCONN 0 0 127.0.0.53%lo:53 0.0.0.0:* users:(("systemd-
resolve",pid=1050,fd=12))
tcp LISTEN 0 4096 127.0.0.53%lo:53 0.0.0.0:* users:(("systemd-
resolve",pid=1050,fd=13))
If the service does not listen on 127.0.0.53:53, check if the systemd-resolved service is running.
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CHAPTER 24. MANAGING THE DEFAULT GATEWAY SETTING
The default gateway is a router that forwards network packets when no other route matches the
destination of a packet. In a local network, the default gateway is typically the host that is one hop closer
to the internet.
24.1. SETTING THE DEFAULT GATEWAY ON AN EXISTING
CONNECTION BY USING NMCLI
In most situations, administrators set the default gateway when they create a connection. However, you
can also set or update the default gateway setting on a previously created connection by using the
nmcli utility.
Prerequisites
At least one static IP address must be configured on the connection on which the default
gateway will be set.
If the user is logged in on a physical console, user permissions are sufficient. Otherwise, user
must have root permissions.
Procedure
1. Set the IP addresses of the default gateway:
To set the IPv4 default gateway, enter:
# nmcli connection modify <connection_name> ipv4.gateway
"<IPv4_gateway_address>"
To set the IPv6 default gateway, enter:
# nmcli connection modify <connection_name> ipv6.gateway
"<IPv6_gateway_address>"
2. Restart the network connection for changes to take effect:
# nmcli connection up <connection_name>
WARNING
All connections currently using this network connection are temporarily
interrupted during the restart.
Verification
Verify that the route is active:
a. To display the IPv4 default gateway, enter:
CHAPTER 24. MANAGING THE DEFAULT GATEWAY SETTING
239
# ip -4 route
default via 192.0.2.1 dev example proto static metric 100
b. To display the IPv6 default gateway, enter:
# ip -6 route
default via 2001:db8:1::1 dev example proto static metric 100 pref medium
24.2. SETTING THE DEFAULT GATEWAY ON AN EXISTING
CONNECTION BY USING THE NMCLI INTERACTIVE MODE
In most situations, administrators set the default gateway when they create a connection. However, you
can also set or update the default gateway setting on a previously created connection by using the
interactive mode of the nmcli utility.
Prerequisites
At least one static IP address must be configured on the connection on which the default
gateway will be set.
If the user is logged in on a physical console, user permissions are sufficient. Otherwise, the user
must have root permissions.
Procedure
1. Open the nmcli interactive mode for the required connection:
# nmcli connection edit <connection_name>
2. Set the default gateway
To set the IPv4 default gateway, enter:
nmcli> set ipv4.gateway "<IPv4_gateway_address>"
To set the IPv6 default gateway, enter:
nmcli> set ipv6.gateway "<IPv6_gateway_address>"
3. Optional: Verify that the default gateway was set correctly:
nmcli> print
...
ipv4.gateway: <IPv4_gateway_address>
...
ipv6.gateway: <IPv6_gateway_address>
...
4. Save the configuration:
nmcli> save persistent
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5. Restart the network connection for changes to take effect:
nmcli> activate <connection_name>
WARNING
All connections currently using this network connection are temporarily
interrupted during the restart.
6. Leave the nmcli interactive mode:
nmcli> quit
Verification
Verify that the route is active:
a. To display the IPv4 default gateway, enter:
# ip -4 route
default via 192.0.2.1 dev example proto static metric 100
b. To display the IPv6 default gateway, enter:
# ip -6 route
default via 2001:db8:1::1 dev example proto static metric 100 pref medium
24.3. SETTING THE DEFAULT GATEWAY ON AN EXISTING
CONNECTION BY USING NM-CONNECTION-EDITOR
In most situations, administrators set the default gateway when they create a connection. However, you
can also set or update the default gateway setting on a previously created connection using the nm-
connection-editor application.
Prerequisites
At least one static IP address must be configured on the connection on which the default
gateway will be set.
Procedure
1. Open a terminal, and enter nm-connection-editor:
# nm-connection-editor
2. Select the connection to modify, and click the gear wheel icon to edit the existing connection.
3. Set the IPv4 default gateway. For example, to set the IPv4 address of the default gateway on
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241
3. Set the IPv4 default gateway. For example, to set the IPv4 address of the default gateway on
the connection to 192.0.2.1:
a. Open the IPv4 Settings tab.
b. Enter the address in the gateway field next to the IP range the gateway’s address is within:
4. Set the IPv6 default gateway. For example, to set the IPv6 address of the default gateway on
the connection to 2001:db8:1::1:
a. Open the IPv6 tab.
b. Enter the address in the gateway field next to the IP range the gateway’s address is within:
5. Click OK.
6. Click Save.
7. Restart the network connection for changes to take effect. For example, to restart the example
connection using the command line:
# nmcli connection up example
WARNING
All connections currently using this network connection are temporarily
interrupted during the restart.
Verification
1. Verify that the route is active.
To display the IPv4 default gateway:
# ip -4 route
default via 192.0.2.1 dev example proto static metric 100
To display the IPv6 default gateway:
# ip -6 route
default via 2001:db8:1::1 dev example proto static metric 100 pref medium
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Additional resources
Configuring an Ethernet connection by using nm-connection-editor
24.4. SETTING THE DEFAULT GATEWAY ON AN EXISTING
CONNECTION BY USING CONTROL-CENTER
In most situations, administrators set the default gateway when they create a connection. However, you
can also set or update the default gateway setting on a previously created connection using the control-
center application.
Prerequisites
At least one static IP address must be configured on the connection on which the default
gateway will be set.
The network configuration of the connection is open in the control-center application.
Procedure
1. Set the IPv4 default gateway. For example, to set the IPv4 address of the default gateway on
the connection to 192.0.2.1:
a. Open the IPv4 tab.
b. Enter the address in the gateway field next to the IP range the gateway’s address is within:
2. Set the IPv6 default gateway. For example, to set the IPv6 address of the default gateway on
the connection to 2001:db8:1::1:
a. Open the IPv6 tab.
b. Enter the address in the gateway field next to the IP range the gateway’s address is within:
3. Click Apply.
4. Back in the Network window, disable and re-enable the connection by switching the button for
the connection to Off and back to On for changes to take effect.
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243
WARNING
All connections currently using this network connection are temporarily
interrupted during the restart.
Verification
1. Verify that the route is active.
To display the IPv4 default gateway:
$ ip -4 route
default via 192.0.2.1 dev example proto static metric 100
To display the IPv6 default gateway:
$ ip -6 route
default via 2001:db8:1::1 dev example proto static metric 100 pref medium
Additional resources
Configuring an Ethernet connection by using control-center
24.5. SETTING THE DEFAULT GATEWAY ON AN EXISTING
CONNECTION BY USING NMSTATECTL
In most situations, administrators set the default gateway when they create a connection. However, you
can also set or update the default gateway setting on a previously created connection by using the
nmstatectl utility.
Use the nmstatectl utility to set the default gateway through the Nmstate API. The Nmstate API
ensures that, after setting the configuration, the result matches the configuration file. If anything fails,
nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.
Prerequisites
At least one static IP address must be configured on the connection on which the default
gateway will be set.
The enp1s0 interface is configured, and the IP address of the default gateway is within the
subnet of the IP configuration of this interface.
The nmstate package is installed.
Procedure
1. Create a YAML file, for example ~/set-default-gateway.yml, with the following content:
---
routes:
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These settings define 192.0.2.1 as the default gateway, and the default gateway is reachable
through the enp1s0 interface.
2. Apply the settings to the system:
# nmstatectl apply ~/set-default-gateway.yml
Additional resources
nmstatectl(8) man page
/usr/share/doc/nmstate/examples/ directory
24.6. SETTING THE DEFAULT GATEWAY ON AN EXISTING
CONNECTION BY USING THE NETWORK RHEL SYSTEM ROLE
A host forwards a network packet to its default gateway if the packet’s destination can neither be
reached through the directly-connected networks nor through any of the routes configured on the host.
To configure the default gateway of a host, set it in the NetworkManager connection profile of the
interface that is connected to the same network as the default gateway. By using Ansible and the
network RHEL system role, you can automate this process and remotely configure connection profiles
on the hosts defined in a playbook.
In most situations, administrators set the default gateway when they create a connection. However, you
can also set or update the default gateway setting on a previously-created connection.
WARNING
You cannot use the network RHEL system role to update only specific values in an
existing connection profile. The role ensures that a connection profile exactly
matches the settings in a playbook. If a connection profile with the same name
already exists, the role applies the settings from the playbook and resets all other
settings in the profile to their defaults. To prevent resetting values, always specify
the whole configuration of the network connection profile in the playbook, including
the settings that you do not want to change.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
config:
- destination: 0.0.0.0/0
next-hop-address: 192.0.2.1
next-hop-interface: enp1s0
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245
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
Query the Ansible facts of the managed node and verify the active network settings:
# ansible managed-node-01.example.com -m ansible.builtin.setup
...
"ansible_default_ipv4": {
...
"gateway": "198.51.100.254",
"interface": "enp1s0",
...
},
---
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: Ethernet connection profile with static IP address settings
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
- name: enp1s0
type: ethernet
autoconnect: yes
ip:
address:
- 198.51.100.20/24
- 2001:db8:1::1/64
gateway4: 198.51.100.254
gateway6: 2001:db8:1::fffe
dns:
- 198.51.100.200
- 2001:db8:1::ffbb
dns_search:
- example.com
state: up
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"ansible_default_ipv6": {
...
"gateway": "2001:db8:1::fffe",
"interface": "enp1s0",
...
}
...
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
24.7. HOW NETWORKMANAGER MANAGES MULTIPLE DEFAULT
GATEWAYS
In certain situations, for example for fallback reasons, you set multiple default gateways on a host.
However, to avoid asynchronous routing issues, each default gateway of the same protocol requires a
separate metric value. Note that RHEL only uses the connection to the default gateway that has the
lowest metric set.
You can set the metric for both the IPv4 and IPv6 gateway of a connection using the following
command:
# nmcli connection modify <connection_name> ipv4.route-metric <value> ipv6.route-metric
<value>
IMPORTANT
Do not set the same metric value for the same protocol in multiple connection profiles to
avoid routing issues.
If you set a default gateway without a metric value, NetworkManager automatically sets the metric value
based on the interface type. For that, NetworkManager assigns the default value of this network type to
the first connection that is activated, and sets an incremented value to each other connection of the
same type in the order they are activated. For example, if two Ethernet connections with a default
gateway exist, NetworkManager sets a metric of 100 on the route to the default gateway of the
connection that you activate first. For the second connection, NetworkManager sets 101.
The following is an overview of frequently-used network types and their default metrics:
Connection type Default metric value
VPN 50
Ethernet 100
MACsec 125
InfiniBand 150
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Bond 300
Team 350
VLAN 400
Bridge 425
TUN 450
Wi-Fi 600
IP tunnel 675
Connection type Default metric value
Additional resources
Configuring policy-based routing to define alternative routes
24.8. CONFIGURING NETWORKMANAGER TO AVOID USING A
SPECIFIC PROFILE TO PROVIDE A DEFAULT GATEWAY
You can configure that NetworkManager never uses a specific profile to provide the default gateway.
Follow this procedure for connection profiles that are not connected to the default gateway.
Prerequisites
The NetworkManager connection profile for the connection that is not connected to the default
gateway exists.
Procedure
1. If the connection uses a dynamic IP configuration, configure that NetworkManager does not
use the connection as the default route for IPv4 and IPv6 connections:
# nmcli connection modify <connection_name> ipv4.never-default yes ipv6.never-
default yes
Note that setting ipv4.never-default and ipv6.never-default to yes, automatically removes the
default gateway’s IP address for the corresponding protocol from the connection profile.
2. Activate the connection:
# nmcli connection up <connection_name>
Verification
Use the ip -4 route and ip -6 route commands to verify that RHEL does not use the network
interface for the default route for the IPv4 and IPv6 protocol.
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24.9. FIXING UNEXPECTED ROUTING BEHAVIOR DUE TO MULTIPLE
DEFAULT GATEWAYS
There are only a few scenarios, such as when using Multipath TCP, in which you require multiple default
gateways on a host. In most cases, you configure only a single default gateway to avoid unexpected
routing behavior or asynchronous routing issues.
NOTE
To route traffic to different internet providers, use policy-based routing instead of
multiple default gateways.
Prerequisites
The host uses NetworkManager to manage network connections, which is the default.
The host has multiple network interfaces.
The host has multiple default gateways configured.
Procedure
1. Display the routing table:
For IPv4, enter:
# ip -4 route
default via 192.0.2.1 dev enp1s0 proto static metric 101
default via 198.51.100.1 dev enp7s0 proto static metric 102
...
For IPv6, enter:
# ip -6 route
default via 2001:db8:1::1 dev enp1s0 proto static metric 101 pref medium
default via 2001:db8:2::1 dev enp7s0 proto static metric 102 pref medium
...
Entries starting with default indicate a default route. Note the interface names of these entries
displayed next to dev.
2. Use the following commands to display the NetworkManager connections that use the
interfaces you identified in the previous step:
# nmcli -f GENERAL.CONNECTION,IP4.GATEWAY,IP6.GATEWAY device show enp1s0
GENERAL.CONNECTION: Corporate-LAN
IP4.GATEWAY: 192.0.2.1
IP6.GATEWAY: 2001:db8:1::1
# nmcli -f GENERAL.CONNECTION,IP4.GATEWAY,IP6.GATEWAY device show enp7s0
GENERAL.CONNECTION: Internet-Provider
IP4.GATEWAY: 198.51.100.1
IP6.GATEWAY: 2001:db8:2::1
In these examples, the profiles named Corporate-LAN and Internet-Provider have the default
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In these examples, the profiles named Corporate-LAN and Internet-Provider have the default
gateways set. Because, in a local network, the default gateway is typically the host that is one
hop closer to the internet, the rest of this procedure assumes that the default gateways in the
Corporate-LAN are incorrect.
3. Configure that NetworkManager does not use the Corporate-LAN connection as the default
route for IPv4 and IPv6 connections:
# nmcli connection modify Corporate-LAN ipv4.never-default yes ipv6.never-default
yes
Note that setting ipv4.never-default and ipv6.never-default to yes, automatically removes the
default gateway’s IP address for the corresponding protocol from the connection profile.
4. Activate the Corporate-LAN connection:
# nmcli connection up Corporate-LAN
Verification
Display the IPv4 and IPv6 routing tables and verify that only one default gateway is available for
each protocol:
For IPv4, enter:
# ip -4 route
default via 192.0.2.1 dev enp1s0 proto static metric 101
...
For IPv6, enter:
# ip -6 route
default via 2001:db8:1::1 dev enp1s0 proto static metric 101 pref medium
...
Additional resources
Configuring policy-based routing to define alternative routes
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CHAPTER 25. CONFIGURING A STATIC ROUTE
Routing ensures that you can send and receive traffic between mutually-connected networks. In larger
environments, administrators typically configure services so that routers can dynamically learn about
other routers. In smaller environments, administrators often configure static routes to ensure that traffic
can reach from one network to the next.
You need static routes to achieve a functioning communication among multiple networks if all of these
conditions apply:
The traffic has to pass multiple networks.
The exclusive traffic flow through the default gateways is not sufficient.
The Example of a network that requires static routes section describes scenarios and how the traffic
flows between different networks when you do not configure static routes.
25.1. EXAMPLE OF A NETWORK THAT REQUIRES STATIC ROUTES
You require static routes in this example because not all IP networks are directly connected through one
router. Without the static routes, some networks cannot communicate with each other. Additionally,
traffic from some networks flows only in one direction.
NOTE
The network topology in this example is artificial and only used to explain the concept of
static routing. It is not a recommended topology in production environments.
For a functioning communication among all networks in this example, configure a static route to Raleigh
(198.51.100.0/24) with next the hop Router 2 ( 203.0.113.10). The IP address of the next hop is the one
of Router 2 in the data center network (203.0.113.0/24).
You can configure the static route as follows:
For a simplified configuration, set this static route only on Router 1. However, this increases the
traffic on Router 1 because hosts from the data center (203.0.113.0/24) send traffic to Raleigh
(198.51.100.0/24) always through Router 1 to Router 2.
For a more complex configuration, configure this static route on all hosts in the data center
(203.0.113.0/24). All hosts in this subnet then send traffic directly to Router 2 ( 203.0.113.10)
that is closer to Raleigh (198.51.100.0/24).
For more details between which networks traffic flows or not, see the explanations below the diagram.
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251
In case that the required static routes are not configured, the following are the situations in which the
communication works and when it does not:
Hosts in the Berlin network (192.0.2.0/24):
Can communicate with other hosts in the same subnet because they are directly connected.
Can communicate with the internet because Router 1 is in the Berlin network (192.0.2.0/24)
and has a default gateway, which leads to the internet.
Can communicate with the data center network (203.0.113.0/24) because Router 1 has
interfaces in both the Berlin (192.0.2.0/24) and the data center (203.0.113.0/24) networks.
Cannot communicate with the Raleigh network (198.51.100.0/24) because Router 1 has no
interface in this network. Therefore, Router 1 sends the traffic to its own default gateway
(internet).
Hosts in the data center network (203.0.113.0/24):
Can communicate with other hosts in the same subnet because they are directly connected.
Can communicate with the internet because they have their default gateway set to Router 1,
and Router 1 has interfaces in both networks, the data center (203.0.113.0/24) and to the
internet.
Can communicate with the Berlin network (192.0.2.0/24) because they have their default
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Can communicate with the Berlin network (192.0.2.0/24) because they have their default
gateway set to Router 1, and Router 1 has interfaces in both the data center (203.0.113.0/24)
and the Berlin (192.0.2.0/24) networks.
Cannot communicate with the Raleigh network (198.51.100.0/24) because the data center
network has no interface in this network. Therefore, hosts in the data center
(203.0.113.0/24) send traffic to their default gateway (Router 1). Router 1 also has no
interface in the Raleigh network (198.51.100.0/24) and, as a result, Router 1 sends this traffic
to its own default gateway (internet).
Hosts in the Raleigh network (198.51.100.0/24):
Can communicate with other hosts in the same subnet because they are directly connected.
Cannot communicate with hosts on the internet. Router 2 sends the traffic to Router 1
because of the default gateway settings. The actual behavior of Router 1 depends on the
reverse path filter (rp_filter) system control (sysctl) setting. By default on RHEL, Router 1
drops the outgoing traffic instead of routing it to the internet. However, regardless of the
configured behavior, communication is not possible without the static route.
Cannot communicate with the data center network (203.0.113.0/24). The outgoing traffic
reaches the destination through Router 2 because of the default gateway setting. However,
replies to packets do not reach the sender because hosts in the data center network
(203.0.113.0/24) send replies to their default gateway (Router 1). Router 1 then sends the
traffic to the internet.
Cannot communicate with the Berlin network (192.0.2.0/24). Router 2 sends the traffic to
Router 1 because of the default gateway settings. The actual behavior of Router 1 depends
on the rp_filter sysctl setting. By default on RHEL, Router 1 drops the outgoing traffic
instead of sending it to the Berlin network (192.0.2.0/24). However, regardless of the
configured behavior, communication is not possible without the static route.
NOTE
In addition to configuring the static routes, you must enable IP forwarding on both
routers.
Additional resources
Why cannot a server be pinged if net.ipv4.conf.all.rp_filter is set on the server?
Enabling IP forwarding
25.2. HOW TO USE THE NMCLI UTILITY TO CONFIGURE A STATIC
ROUTE
To configure a static route, use the nmcli utility with the following syntax:
$ nmcli connection modify connection_name ipv4.routes "ip[/prefix] [next_hop] [metric]
[attribute=value] [attribute=value] ..."
The command supports the following route attributes:
cwnd=n: Sets the congestion window (CWND) size, defined in number of packets.
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lock-cwnd=true|false: Defines whether or not the kernel can update the CWND value.
lock-mtu=true|false: Defines whether or not the kernel can update the MTU to path MTU
discovery.
lock-window=true|false: Defines whether or not the kernel can update the maximum window
size for TCP packets.
mtu=<mtu_value>: Sets the maximum transfer unit (MTU) to use along the path to the
destination.
onlink=true|false: Defines whether the next hop is directly attached to this link even if it does
not match any interface prefix.
scope=<scope>: For an IPv4 route, this attribute sets the scope of the destinations covered by
the route prefix. Set the value as an integer (0-255).
src=<source_address>: Sets the source address to prefer when sending traffic to the
destinations covered by the route prefix.
table=<table_id>: Sets the ID of the table the route should be added to. If you omit this
parameter, NetworkManager uses the main table.
tos=<type_of_service_key>: Sets the type of service (TOS) key. Set the value as an integer
(0-255).
type=<route_type>: Sets the route type. NetworkManager supports the unicast, local,
blackhole, unreachable, prohibit, and throw route types. The default is unicast.
window=<window_size>: Sets the maximal window size for TCP to advertise to these
destinations, measured in bytes.
IMPORTANT
If you use the ipv4.routes option without a preceding + sign, nmcli overrides all current
settings of this parameter.
To create an additional route, enter:
$ nmcli connection modify connection_name +ipv4.routes "<route>"
To remove a specific route, enter:
$ nmcli connection modify connection_name -ipv4.routes "<route>"
25.3. CONFIGURING A STATIC ROUTE BY USING NMCLI
You can add a static route to an existing NetworkManager connection profile using the nmcli
connection modify command.
The procedure below configures the following routes:
An IPv4 route to the remote 198.51.100.0/24 network. The corresponding gateway with the IP
address 192.0.2.10 is reachable through the LAN connection profile.
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An IPv6 route to the remote 2001:db8:2::/64 network. The corresponding gateway with the IP
address 2001:db8:1::10 is reachable through the LAN connection profile.
Prerequisites
The LAN connection profile exists and it configures this host to be in the same IP subnet as the
gateways.
Procedure
1. Add the static IPv4 route to the LAN connection profile:
# nmcli connection modify LAN +ipv4.routes "198.51.100.0/24 192.0.2.10"
To set multiple routes in one step, pass the individual routes comma-separated to the
command:
# nmcli connection modify <connection_profile> +ipv4.routes
"<remote_network_1>/<subnet_mask_1> <gateway_1>,
<remote_network_n>/<subnet_mask_n> <gateway_n>, ..."
2. Add the static IPv6 route to the LAN connection profile:
# nmcli connection modify LAN +ipv6.routes "2001:db8:2::/64 2001:db8:1::10"
3. Re-activate the connection:
# nmcli connection up LAN
Verification
1. Display the IPv4 routes:
# ip -4 route
...
198.51.100.0/24 via 192.0.2.10 dev enp1s0
2. Display the IPv6 routes:
# ip -6 route
...
2001:db8:2::/64 via 2001:db8:1::10 dev enp1s0 metric 1024 pref medium
25.4. CONFIGURING A STATIC ROUTE BY USING NMTUI
The nmtui application provides a text-based user interface for NetworkManager. You can use nmtui to
configure static routes on a host without a graphical interface.
For example, the procedure below adds a route to the 192.0.2.0/24 network that uses the gateway
running on 198.51.100.1, which is reachable through an existing connection profile.
NOTE
CHAPTER 25. CONFIGURING A STATIC ROUTE
255
NOTE
In nmtui:
Navigate by using the cursor keys.
Press a button by selecting it and hitting Enter.
Select and clear checkboxes by using Space.
Prerequisites
The network is configured.
The gateway for the static route must be directly reachable on the interface.
If the user is logged in on a physical console, user permissions are sufficient. Otherwise, the
command requires root permissions.
Procedure
1. Start nmtui:
# nmtui
2. Select Edit a connection, and press Enter.
3. Select the connection profile through which you can reach the next hop to the destination
network, and press Enter.
4. Depending on whether it is an IPv4 or IPv6 route, press the Show button next to the protocol’s
configuration area.
5. Press the Edit button next to Routing. This opens a new window where you configure static
routes:
a. Press the Add button and fill in:
The destination network, including the prefix in Classless Inter-Domain Routing (CIDR)
format
The IP address of the next hop
A metric value, if you add multiple routes to the same network and want to prioritize the
routes by efficiency
b. Repeat the previous step for every route you want to add and that is reachable through this
connection profile.
c. Press the OK button to return to the window with the connection settings.
Figure 25.1. Example of a static route without metric
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Figure 25.1. Example of a static route without metric
6. Press the OK button to return to the nmtui main menu.
7. Select Activate a connection and press Enter.
8. Select the connection profile that you edited, and press Enter twice to deactivate and activate
it again.
IMPORTANT
Skip this step if you run nmtui over a remote connection, such as SSH, that uses
the connection profile you want to reactivate. In this case, if you would deactivate
it in nmtui, the connection is terminated and, consequently, you cannot activate
it again. To avoid this problem, use the nmcli connection <connection_profile>
up command to reactivate the connection in the mentioned scenario.
9. Press the Back button to return to the main menu.
10. Select Quit, and press Enter to close the nmtui application.
Verification
Verify that the route is active:
$ ip route
...
192.0.2.0/24 via 198.51.100.1 dev example proto static metric 100
25.5. CONFIGURING A STATIC ROUTE BY USING CONTROL-CENTER
You can use control-center in GNOME to add a static route to the configuration of a network
connection.
The procedure below configures the following routes:
An IPv4 route to the remote 198.51.100.0/24 network. The corresponding gateway has the IP
address 192.0.2.10.
An IPv6 route to the remote 2001:db8:2::/64 network. The corresponding gateway has the IP
address 2001:db8:1::10.
Prerequisites
The network is configured.
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257
This host is in the same IP subnet as the gateways.
The network configuration of the connection is opened in the control-center application. See
Configuring an Ethernet connection by using nm-connection-editor .
Procedure
1. On the IPv4 tab:
a. Optional: Disable automatic routes by clicking the On button in the Routes section of the
IPv4 tab to use only static routes. If automatic routes are enabled, Red Hat Enterprise Linux
uses static routes and routes received from a DHCP server.
b. Enter the address, netmask, gateway, and optionally a metric value of the IPv4 route:
2. On the IPv6 tab:
a. Optional: Disable automatic routes by clicking the On button i the Routes section of the
IPv4 tab to use only static routes.
b. Enter the address, netmask, gateway, and optionally a metric value of the IPv6 route:
3. Click Apply.
4. Back in the Network window, disable and re-enable the connection by switching the button for
the connection to Off and back to On for changes to take effect.
WARNING
Restarting the connection briefly disrupts connectivity on that interface.
Verification
1. Display the IPv4 routes:
# ip -4 route
...
198.51.100.0/24 via 192.0.2.10 dev enp1s0
2. Display the IPv6 routes:
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# ip -6 route
...
2001:db8:2::/64 via 2001:db8:1::10 dev enp1s0 metric 1024 pref medium
25.6. CONFIGURING A STATIC ROUTE BY USING NM-CONNECTION-
EDITOR
You can use the nm-connection-editor application to add a static route to the configuration of a
network connection.
The procedure below configures the following routes:
An IPv4 route to the remote 198.51.100.0/24 network. The corresponding gateway with the IP
address 192.0.2.10 is reachable through the example connection.
An IPv6 route to the remote 2001:db8:2::/64 network. The corresponding gateway with the IP
address 2001:db8:1::10 is reachable through the example connection.
Prerequisites
The network is configured.
This host is in the same IP subnet as the gateways.
Procedure
1. Open a terminal, and enter nm-connection-editor:
$ nm-connection-editor
2. Select the example connection profile, and click the gear wheel icon to edit the existing
connection.
3. On the IPv4 Settings tab:
a. Click the Routes button.
b. Click the Add button and enter the address, netmask, gateway, and optionally a metric
value.
c. Click OK.
4. On the IPv6 Settings tab:
a. Click the Routes button.
b. Click the Add button and enter the address, netmask, gateway, and optionally a metric
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259
b. Click the Add button and enter the address, netmask, gateway, and optionally a metric
value.
c. Click OK.
5. Click Save.
6. Restart the network connection for changes to take effect. For example, to restart the example
connection using the command line:
# nmcli connection up example
Verification
1. Display the IPv4 routes:
# ip -4 route
...
198.51.100.0/24 via 192.0.2.10 dev enp1s0
2. Display the IPv6 routes:
# ip -6 route
...
2001:db8:2::/64 via 2001:db8:1::10 dev enp1s0 metric 1024 pref medium
25.7. CONFIGURING A STATIC ROUTE BY USING THE NMCLI
INTERACTIVE MODE
You can use the interactive mode of the nmcli utility to add a static route to the configuration of a
network connection.
The procedure below configures the following routes:
An IPv4 route to the remote 198.51.100.0/24 network. The corresponding gateway with the IP
address 192.0.2.10 is reachable through the example connection.
An IPv6 route to the remote 2001:db8:2::/64 network. The corresponding gateway with the IP
address 2001:db8:1::10 is reachable through the example connection.
Prerequisites
The example connection profile exists and it configures this host to be in the same IP subnet as
the gateways.
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Procedure
1. Open the nmcli interactive mode for the example connection:
# nmcli connection edit example
2. Add the static IPv4 route:
nmcli> set ipv4.routes 198.51.100.0/24 192.0.2.10
3. Add the static IPv6 route:
nmcli> set ipv6.routes 2001:db8:2::/64 2001:db8:1::10
4. Optional: Verify that the routes were added correctly to the configuration:
nmcli> print
...
ipv4.routes: { ip = 198.51.100.0/24, nh = 192.0.2.10 }
...
ipv6.routes: { ip = 2001:db8:2::/64, nh = 2001:db8:1::10 }
...
The ip attribute displays the network to route and the nh attribute the gateway (next hop).
5. Save the configuration:
nmcli> save persistent
6. Restart the network connection:
nmcli> activate example
7. Leave the nmcli interactive mode:
nmcli> quit
Verification
1. Display the IPv4 routes:
# ip -4 route
...
198.51.100.0/24 via 192.0.2.10 dev enp1s0
2. Display the IPv6 routes:
# ip -6 route
...
2001:db8:2::/64 via 2001:db8:1::10 dev enp1s0 metric 1024 pref medium
Additional resources
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261
Additional resources
nmcli(1) man page
nm-settings-nmcli(5) man page
25.8. CONFIGURING A STATIC ROUTE BY USING NMSTATECTL
Use the nmstatectl utility to configure a static route through the Nmstate API. The Nmstate API
ensures that, after setting the configuration, the result matches the configuration file. If anything fails,
nmstatectl automatically rolls back the changes to avoid leaving the system in an incorrect state.
Prerequisites
The enp1s0 network interface is configured and is in the same IP subnet as the gateways.
The nmstate package is installed.
Procedure
1. Create a YAML file, for example ~/add-static-route-to-enp1s0.yml, with the following content:
These settings define the following static routes:
An IPv4 route to the remote 198.51.100.0/24 network. The corresponding gateway with the
IP address 192.0.2.10 is reachable through the enp1s0 interface.
An IPv6 route to the remote 2001:db8:2::/64 network. The corresponding gateway with the
IP address 2001:db8:1::10 is reachable through the enp1s0 interface.
2. Apply the settings to the system:
# nmstatectl apply ~/add-static-route-to-enp1s0.yml
Verification
1. Display the IPv4 routes:
# ip -4 route
...
198.51.100.0/24 via 192.0.2.10 dev enp1s0
2. Display the IPv6 routes:
---
routes:
config:
- destination: 198.51.100.0/24
next-hop-address: 192.0.2.10
next-hop-interface: enp1s0
- destination: 2001:db8:2::/64
next-hop-address: 2001:db8:1::10
next-hop-interface: enp1s0
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# ip -6 route
...
2001:db8:2::/64 via 2001:db8:1::10 dev enp1s0 metric 1024 pref medium
Additional resources
nmstatectl(8) man page
/usr/share/doc/nmstate/examples/ directory
25.9. CONFIGURING A STATIC ROUTE BY USING THE NETWORK RHEL
SYSTEM ROLE
A static route ensures that you can send traffic to a destination that cannot be reached through the
default gateway. You configure static routes in the NetworkManager connection profile of the interface
that is connected to the same network as the next hop. By using Ansible and the network RHEL system
role, you can automate this process and remotely configure connection profiles on the hosts defined in a
playbook.
WARNING
You cannot use the network RHEL system role to update only specific values in an
existing connection profile. The role ensures that a connection profile exactly
matches the settings in a playbook. If a connection profile with the same name
already exists, the role applies the settings from the playbook and resets all other
settings in the profile to their defaults. To prevent resetting values, always specify
the whole configuration of the network connection profile in the playbook, including
the settings that you do not want to change.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
---
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: Ethernet connection profile with static IP address settings
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
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For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
1. Display the IPv4 routes:
# ansible managed-node-01.example.com -m command -a 'ip -4 route'
managed-node-01.example.com | CHANGED | rc=0 >>
...
198.51.100.0/24 via 192.0.2.10 dev enp7s0
2. Display the IPv6 routes:
# ansible managed-node-01.example.com -m command -a 'ip -6 route'
managed-node-01.example.com | CHANGED | rc=0 >>
...
2001:db8:2::/64 via 2001:db8:1::10 dev enp7s0 metric 1024 pref medium
network_connections:
- name: enp7s0
type: ethernet
autoconnect: yes
ip:
address:
- 192.0.2.1/24
- 2001:db8:1::1/64
gateway4: 192.0.2.254
gateway6: 2001:db8:1::fffe
dns:
- 192.0.2.200
- 2001:db8:1::ffbb
dns_search:
- example.com
route:
- network: 198.51.100.0
prefix: 24
gateway: 192.0.2.10
- network: 2001:db8:2::
prefix: 64
gateway: 2001:db8:1::10
state: up
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Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
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CHAPTER 26. CONFIGURING POLICY-BASED ROUTING TO
DEFINE ALTERNATIVE ROUTES
By default, the kernel in RHEL decides where to forward network packets based on the destination
address using a routing table. Policy-based routing enables you to configure complex routing scenarios.
For example, you can route packets based on various criteria, such as the source address, packet
metadata, or protocol.
26.1. ROUTING TRAFFIC FROM A SPECIFIC SUBNET TO A DIFFERENT
DEFAULT GATEWAY BY USING NMCLI
You can use policy-based routing to configure a different default gateway for traffic from certain
subnets. For example, you can configure RHEL as a router that, by default, routes all traffic to internet
provider A using the default route. However, traffic received from the internal workstations subnet is
routed to provider B.
The procedure assumes the following network topology:
Prerequisites
The system uses NetworkManager to configure the network, which is the default.
The RHEL router you want to set up in the procedure has four network interfaces:
The enp7s0 interface is connected to the network of provider A. The gateway IP in the
provider’s network is 198.51.100.2, and the network uses a /30 network mask.
The enp1s0 interface is connected to the network of provider B. The gateway IP in the
provider’s network is 192.0.2.2, and the network uses a /30 network mask.
The enp8s0 interface is connected to the 10.0.0.0/24 subnet with internal workstations.
The enp9s0 interface is connected to the 203.0.113.0/24 subnet with the company’s
servers.
Hosts in the internal workstations subnet use 10.0.0.1 as the default gateway. In the procedure,
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Hosts in the internal workstations subnet use 10.0.0.1 as the default gateway. In the procedure,
you assign this IP address to the enp8s0 network interface of the router.
Hosts in the server subnet use 203.0.113.1 as the default gateway. In the procedure, you assign
this IP address to the enp9s0 network interface of the router.
The firewalld service is enabled and active.
Procedure
1. Configure the network interface to provider A:
# nmcli connection add type ethernet con-name Provider-A ifname enp7s0
ipv4.method manual ipv4.addresses 198.51.100.1/30 ipv4.gateway 198.51.100.2
ipv4.dns 198.51.100.200 connection.zone external
The nmcli connection add command creates a NetworkManager connection profile. The
command uses the following options:
type ethernet: Defines that the connection type is Ethernet.
con-name <connection_name>: Sets the name of the profile. Use a meaningful name to
avoid confusion.
ifname <network_device>: Sets the network interface.
ipv4.method manual: Enables to configure a static IP address.
ipv4.addresses <IP_address>/<subnet_mask>: Sets the IPv4 addresses and subnet mask.
ipv4.gateway <IP_address>: Sets the default gateway address.
ipv4.dns <IP_of_DNS_server>: Sets the IPv4 address of the DNS server.
connection.zone <firewalld_zone>: Assigns the network interface to the defined firewalld
zone. Note that firewalld automatically enables masquerading for interfaces assigned to
the external zone.
2. Configure the network interface to provider B:
# nmcli connection add type ethernet con-name Provider-B ifname enp1s0
ipv4.method manual ipv4.addresses 192.0.2.1/30 ipv4.routes "0.0.0.0/0 192.0.2.2
table=5000" connection.zone external
This command uses the ipv4.routes parameter instead of ipv4.gateway to set the default
gateway. This is required to assign the default gateway for this connection to a different routing
table (5000) than the default. NetworkManager automatically creates this new routing table
when the connection is activated.
3. Configure the network interface to the internal workstations subnet:
# nmcli connection add type ethernet con-name Internal-Workstations ifname enp8s0
ipv4.method manual ipv4.addresses 10.0.0.1/24 ipv4.routes "10.0.0.0/24 table=5000"
ipv4.routing-rules "priority 5 from 10.0.0.0/24 table 5000" connection.zone trusted
This command uses the ipv4.routes parameter to add a static route to the routing table with ID
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267
This command uses the ipv4.routes parameter to add a static route to the routing table with ID
5000. This static route for the 10.0.0.0/24 subnet uses the IP of the local network interface to
provider B (192.0.2.1) as next hop.
Additionally, the command uses the ipv4.routing-rules parameter to add a routing rule with
priority 5 that routes traffic from the 10.0.0.0/24 subnet to table 5000. Low values have a high
priority.
Note that the syntax in the ipv4.routing-rules parameter is the same as in an ip rule add
command, except that ipv4.routing-rules always requires specifying a priority.
4. Configure the network interface to the server subnet:
# nmcli connection add type ethernet con-name Servers ifname enp9s0 ipv4.method
manual ipv4.addresses 203.0.113.1/24 connection.zone trusted
Verification
1. On a RHEL host in the internal workstation subnet:
a. Install the traceroute package:
# dnf install traceroute
b. Use the traceroute utility to display the route to a host on the internet:
# traceroute redhat.com
traceroute to redhat.com (209.132.183.105), 30 hops max, 60 byte packets
1 10.0.0.1 (10.0.0.1) 0.337 ms 0.260 ms 0.223 ms
2 192.0.2.1 (192.0.2.1) 0.884 ms 1.066 ms 1.248 ms
...
The output of the command displays that the router sends packets over 192.0.2.1, which is
the network of provider B.
2. On a RHEL host in the server subnet:
a. Install the traceroute package:
# dnf install traceroute
b. Use the traceroute utility to display the route to a host on the internet:
# traceroute redhat.com
traceroute to redhat.com (209.132.183.105), 30 hops max, 60 byte packets
1 203.0.113.1 (203.0.113.1) 2.179 ms 2.073 ms 1.944 ms
2 198.51.100.2 (198.51.100.2) 1.868 ms 1.798 ms 1.549 ms
...
The output of the command displays that the router sends packets over 198.51.100.2, which
is the network of provider A.
Troubleshooting steps
On the RHEL router:
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1. Display the rule list:
# ip rule list
0: from all lookup local
5: from 10.0.0.0/24 lookup 5000
32766: from all lookup main
32767: from all lookup default
By default, RHEL contains rules for the tables local, main, and default.
2. Display the routes in table 5000:
# ip route list table 5000
0.0.0.0/0 via 192.0.2.2 dev enp1s0 proto static metric 100
10.0.0.0/24 dev enp8s0 proto static scope link src 192.0.2.1 metric 102
3. Display the interfaces and firewall zones:
# firewall-cmd --get-active-zones
external
interfaces: enp1s0 enp7s0
trusted
interfaces: enp8s0 enp9s0
4. Verify that the external zone has masquerading enabled:
# firewall-cmd --info-zone=external
external (active)
target: default
icmp-block-inversion: no
interfaces: enp1s0 enp7s0
sources:
services: ssh
ports:
protocols:
masquerade: yes
...
Additional resources
nm-settings(5) man page
nmcli(1) man page
26.2. ROUTING TRAFFIC FROM A SPECIFIC SUBNET TO A DIFFERENT
DEFAULT GATEWAY BY USING THE NETWORK RHEL SYSTEM ROLE
You can use policy-based routing to configure a different default gateway for traffic from certain
subnets. For example, you can configure RHEL as a router that, by default, routes all traffic to internet
provider A using the default route. However, traffic received from the internal workstations subnet is
routed to provider B. By using Ansible and the network RHEL system role, you can automate this
process and remotely configure connection profiles on the hosts defined in a playbook.
You can use the network RHEL system role to configure the connection profiles, including routing
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269
You can use the network RHEL system role to configure the connection profiles, including routing
tables and rules.
This procedure assumes the following network topology:
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
The managed nodes uses the NetworkManager and firewalld services.
The managed nodes you want to configure has four network interfaces:
The enp7s0 interface is connected to the network of provider A. The gateway IP in the
provider’s network is 198.51.100.2, and the network uses a /30 network mask.
The enp1s0 interface is connected to the network of provider B. The gateway IP in the
provider’s network is 192.0.2.2, and the network uses a /30 network mask.
The enp8s0 interface is connected to the 10.0.0.0/24 subnet with internal workstations.
The enp9s0 interface is connected to the 203.0.113.0/24 subnet with the company’s
servers.
Hosts in the internal workstations subnet use 10.0.0.1 as the default gateway. In the procedure,
you assign this IP address to the enp8s0 network interface of the router.
Hosts in the server subnet use 203.0.113.1 as the default gateway. In the procedure, you assign
this IP address to the enp9s0 network interface of the router.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
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---
- name: Configuring policy-based routing
hosts: managed-node-01.example.com
tasks:
- name: Routing traffic from a specific subnet to a different default gateway
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
- name: Provider-A
interface_name: enp7s0
type: ethernet
autoconnect: True
ip:
address:
- 198.51.100.1/30
gateway4: 198.51.100.2
dns:
- 198.51.100.200
state: up
zone: external
- name: Provider-B
interface_name: enp1s0
type: ethernet
autoconnect: True
ip:
address:
- 192.0.2.1/30
route:
- network: 0.0.0.0
prefix: 0
gateway: 192.0.2.2
table: 5000
state: up
zone: external
- name: Internal-Workstations
interface_name: enp8s0
type: ethernet
autoconnect: True
ip:
address:
- 10.0.0.1/24
route:
- network: 10.0.0.0
prefix: 24
table: 5000
routing_rule:
- priority: 5
from: 10.0.0.0/24
table: 5000
state: up
zone: trusted
- name: Servers
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The settings specified in the example playbook include the following:
table: <value>
Assigns the route from the same list entry as the table variable to the specified routing table.
routing_rule: <list>
Defines the priority of the specified routing rule and from a connection profile to which
routing table the rule is assigned.
zone: <zone_name>
Assigns the network interface from a connection profile to the specified firewalld zone.
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
1. On a RHEL host in the internal workstation subnet:
a. Install the traceroute package:
# dnf install traceroute
b. Use the traceroute utility to display the route to a host on the internet:
# traceroute redhat.com
traceroute to redhat.com (209.132.183.105), 30 hops max, 60 byte packets
1 10.0.0.1 (10.0.0.1) 0.337 ms 0.260 ms 0.223 ms
2 192.0.2.1 (192.0.2.1) 0.884 ms 1.066 ms 1.248 ms
...
The output of the command displays that the router sends packets over 192.0.2.1, which is
the network of provider B.
2. On a RHEL host in the server subnet:
a. Install the traceroute package:
interface_name: enp9s0
type: ethernet
autoconnect: True
ip:
address:
- 203.0.113.1/24
state: up
zone: trusted
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a. Install the traceroute package:
# dnf install traceroute
b. Use the traceroute utility to display the route to a host on the internet:
# traceroute redhat.com
traceroute to redhat.com (209.132.183.105), 30 hops max, 60 byte packets
1 203.0.113.1 (203.0.113.1) 2.179 ms 2.073 ms 1.944 ms
2 198.51.100.2 (198.51.100.2) 1.868 ms 1.798 ms 1.549 ms
...
The output of the command displays that the router sends packets over 198.51.100.2, which
is the network of provider A.
3. On the RHEL router that you configured using the RHEL system role:
a. Display the rule list:
# ip rule list
0: from all lookup local
5: from 10.0.0.0/24 lookup 5000
32766: from all lookup main
32767: from all lookup default
By default, RHEL contains rules for the tables local, main, and default.
b. Display the routes in table 5000:
# ip route list table 5000
0.0.0.0/0 via 192.0.2.2 dev enp1s0 proto static metric 100
10.0.0.0/24 dev enp8s0 proto static scope link src 192.0.2.1 metric 102
c. Display the interfaces and firewall zones:
# firewall-cmd --get-active-zones
external
interfaces: enp1s0 enp7s0
trusted
interfaces: enp8s0 enp9s0
d. Verify that the external zone has masquerading enabled:
# firewall-cmd --info-zone=external
external (active)
target: default
icmp-block-inversion: no
interfaces: enp1s0 enp7s0
sources:
services: ssh
ports:
protocols:
masquerade: yes
...
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Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
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CHAPTER 27. REUSING THE SAME IP ADDRESS ON
DIFFERENT INTERFACES
With Virtual routing and forwarding (VRF), administrators can use multiple routing tables simultaneously
on the same host. For that, VRF partitions a network at layer 3. This enables the administrator to isolate
traffic using separate and independent route tables per VRF domain. This technique is similar to virtual
LANs (VLAN), which partitions a network at layer 2, where the operating system uses different VLAN
tags to isolate traffic sharing the same physical medium.
One benefit of VRF over partitioning on layer 2 is that routing scales better considering the number of
peers involved.
Red Hat Enterprise Linux uses a virtual vrt device for each VRF domain and adds routes to a VRF
domain by adding existing network devices to a VRF device. Addresses and routes previously attached
to the original device will be moved inside the VRF domain.
Note that each VRF domain is isolated from each other.
27.1. PERMANENTLY REUSING THE SAME IP ADDRESS ON DIFFERENT
INTERFACES
You can use the virtual routing and forwarding (VRF) feature to permanently use the same IP address
on different interfaces in one server.
IMPORTANT
To enable remote peers to contact both VRF interfaces while reusing the same IP
address, the network interfaces must belong to different broadcasting domains. A
broadcast domain in a network is a set of nodes, which receive broadcast traffic sent by
any of them. In most configurations, all nodes connected to the same switch belong to
the same broadcasting domain.
Prerequisites
You are logged in as the root user.
The network interfaces are not configured.
Procedure
1. Create and configure the first VRF device:
a. Create a connection for the VRF device and assign it to a routing table. For example, to
create a VRF device named vrf0 that is assigned to the 1001 routing table:
# nmcli connection add type vrf ifname vrf0 con-name vrf0 table 1001 ipv4.method
disabled ipv6.method disabled
b. Enable the vrf0 device:
# nmcli connection up vrf0
c. Assign a network device to the VRF just created. For example, to add the enp1s0 Ethernet
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275
c. Assign a network device to the VRF just created. For example, to add the enp1s0 Ethernet
device to the vrf0 VRF device and assign an IP address and the subnet mask to enp1s0,
enter:
# nmcli connection add type ethernet con-name vrf.enp1s0 ifname enp1s0
controller vrf0 ipv4.method manual ipv4.address 192.0.2.1/24
d. Activate the vrf.enp1s0 connection:
# nmcli connection up vrf.enp1s0
2. Create and configure the next VRF device:
a. Create the VRF device and assign it to a routing table. For example, to create a VRF device
named vrf1 that is assigned to the 1002 routing table, enter:
# nmcli connection add type vrf ifname vrf1 con-name vrf1 table 1002 ipv4.method
disabled ipv6.method disabled
b. Activate the vrf1 device:
# nmcli connection up vrf1
c. Assign a network device to the VRF just created. For example, to add the enp7s0 Ethernet
device to the vrf1 VRF device and assign an IP address and the subnet mask to enp7s0,
enter:
# nmcli connection add type ethernet con-name vrf.enp7s0 ifname enp7s0
controller vrf1 ipv4.method manual ipv4.address 192.0.2.1/24
d. Activate the vrf.enp7s0 device:
# nmcli connection up vrf.enp7s0
27.2. TEMPORARILY REUSING THE SAME IP ADDRESS ON DIFFERENT
INTERFACES
You can use the virtual routing and forwarding (VRF) feature to temporarily use the same IP address on
different interfaces in one server. Use this procedure only for testing purposes, because the
configuration is temporary and lost after you reboot the system.
IMPORTANT
To enable remote peers to contact both VRF interfaces while reusing the same IP
address, the network interfaces must belong to different broadcasting domains. A
broadcast domain in a network is a set of nodes which receive broadcast traffic sent by
any of them. In most configurations, all nodes connected to the same switch belong to
the same broadcasting domain.
Prerequisites
You are logged in as the root user.
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The network interfaces are not configured.
Procedure
1. Create and configure the first VRF device:
a. Create the VRF device and assign it to a routing table. For example, to create a VRF device
named blue that is assigned to the 1001 routing table:
# ip link add dev blue type vrf table 1001
b. Enable the blue device:
# ip link set dev blue up
c. Assign a network device to the VRF device. For example, to add the enp1s0 Ethernet
device to the blue VRF device:
# ip link set dev enp1s0 master blue
d. Enable the enp1s0 device:
# ip link set dev enp1s0 up
e. Assign an IP address and subnet mask to the enp1s0 device. For example, to set it to
192.0.2.1/24:
# ip addr add dev enp1s0 192.0.2.1/24
2. Create and configure the next VRF device:
a. Create the VRF device and assign it to a routing table. For example, to create a VRF device
named red that is assigned to the 1002 routing table:
# ip link add dev red type vrf table 1002
b. Enable the red device:
# ip link set dev red up
c. Assign a network device to the VRF device. For example, to add the enp7s0 Ethernet
device to the red VRF device:
# ip link set dev enp7s0 master red
d. Enable the enp7s0 device:
# ip link set dev enp7s0 up
e. Assign the same IP address and subnet mask to the enp7s0 device as you used for enp1s0
in the blue VRF domain:
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277
# ip addr add dev enp7s0 192.0.2.1/24
3. Optional: Create further VRF devices as described above.
27.3. ADDITIONAL RESOURCES
/usr/share/doc/kernel-doc-<kernel_version>/Documentation/networking/vrf.txt from the
kernel-doc package
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CHAPTER 28. STARTING A SERVICE WITHIN AN ISOLATED
VRF NETWORK
With virtual routing and forwarding (VRF), you can create isolated networks with a routing table that is
different to the main routing table of the operating system. You can then start services and applications
so that they have only access to the network defined in that routing table.
28.1. CONFIGURING A VRF DEVICE
To use virtual routing and forwarding (VRF), you create a VRF device and attach a physical or virtual
network interface and routing information to it.
WARNING
To prevent that you lock out yourself out remotely, perform this procedure on the
local console or remotely over a network interface that you do not want to assign to
the VRF device.
Prerequisites
You are logged in locally or using a network interface that is different to the one you want to
assign to the VRF device.
Procedure
1. Create the vrf0 connection with a same-named virtual device, and attach it to routing table
1000:
# nmcli connection add type vrf ifname vrf0 con-name vrf0 table 1000 ipv4.method
disabled ipv6.method disabled
2. Add the enp1s0 device to the vrf0 connection, and configure the IP settings:
# nmcli connection add type ethernet con-name enp1s0 ifname enp1s0 controller vrf0
ipv4.method manual ipv4.address 192.0.2.1/24 ipv4.gateway 192.0.2.254
This command creates the enp1s0 connection as a port of the vrf0 connection. Due to this
configuration, the routing information are automatically assigned to the routing table 1000 that
is associated with the vrf0 device.
3. If you require static routes in the isolated network:
a. Add the static routes:
# nmcli connection modify enp1s0 +ipv4.routes "198.51.100.0/24 192.0.2.2"
This adds a route to the 198.51.100.0/24 network that uses 192.0.2.2 as the router.
b. Activate the connection:
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279
# nmcli connection up enp1s0
Verification
1. Display the IP settings of the device that is associated with vrf0:
# ip -br addr show vrf vrf0
enp1s0 UP 192.0.2.1/24
2. Display the VRF devices and their associated routing table:
# ip vrf show
Name Table
-----------------------
vrf0 1000
3. Display the main routing table:
# ip route show
default via 203.0.113.0/24 dev enp7s0 proto static metric 100
The main routing table does not mention any routes associated with the device enp1s0 device
or the 192.0.2.1/24 subnet.
4. Display the routing table 1000:
# ip route show table 1000
default via 192.0.2.254 dev enp1s0 proto static metric 101
broadcast 192.0.2.0 dev enp1s0 proto kernel scope link src 192.0.2.1
192.0.2.0/24 dev enp1s0 proto kernel scope link src 192.0.2.1 metric 101
local 192.0.2.1 dev enp1s0 proto kernel scope host src 192.0.2.1
broadcast 192.0.2.255 dev enp1s0 proto kernel scope link src 192.0.2.1
198.51.100.0/24 via 192.0.2.2 dev enp1s0 proto static metric 101
The default entry indicates that services that use this routing table, use 192.0.2.254 as their
default gateway and not the default gateway in the main routing table.
5. Execute the traceroute utility in the network associated with vrf0 to verify that the utility uses
the route from table 1000:
# ip vrf exec vrf0 traceroute 203.0.113.1
traceroute to 203.0.113.1 (203.0.113.1), 30 hops max, 60 byte packets
1 192.0.2.254 (192.0.2.254) 0.516 ms 0.459 ms 0.430 ms
...
The first hop is the default gateway that is assigned to the routing table 1000 and not the
default gateway from the system’s main routing table.
Additional resources
ip-vrf(8) man page
28.2. STARTING A SERVICE WITHIN AN ISOLATED VRF NETWORK
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You can configure a service, such as the Apache HTTP Server, to start within an isolated virtual routing
and forwarding (VRF) network.
IMPORTANT
Services can only bind to local IP addresses that are in the same VRF network.
Prerequisites
You configured the vrf0 device.
You configured Apache HTTP Server to listen only on the IP address that is assigned to the
interface associated with the vrf0 device.
Procedure
1. Display the content of the httpd systemd service:
# systemctl cat httpd
...
[Service]
ExecStart=/usr/sbin/httpd $OPTIONS -DFOREGROUND
...
You require the content of the ExecStart parameter in a later step to run the same command
within the isolated VRF network.
2. Create the /etc/systemd/system/httpd.service.d/ directory:
# mkdir /etc/systemd/system/httpd.service.d/
3. Create the /etc/systemd/system/httpd.service.d/override.conf file with the following content:
[Service]
ExecStart=
ExecStart=/usr/sbin/ip vrf exec vrf0 /usr/sbin/httpd $OPTIONS -DFOREGROUND
To override the ExecStart parameter, you first need to unset it and then set it to the new value
as shown.
4. Reload systemd.
# systemctl daemon-reload
5. Restart the httpd service.
# systemctl restart httpd
Verification
1. Display the process IDs (PID) of httpd processes:
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281
# pidof -c httpd
1904 ...
2. Display the VRF association for the PIDs, for example:
# ip vrf identify 1904
vrf0
3. Display all PIDs associated with the vrf0 device:
# ip vrf pids vrf0
1904 httpd
...
Additional resources
ip-vrf(8) man page
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CHAPTER 29. CONFIGURING ETHTOOL SETTINGS IN
NETWORKMANAGER CONNECTION PROFILES
NetworkManager can configure certain network driver and hardware settings persistently. Compared to
using the ethtool utility to manage these settings, this has the benefit of not losing the settings after a
reboot.
You can set the following ethtool settings in NetworkManager connection profiles:
Offload features
Network interface controllers can use the TCP offload engine (TOE) to offload processing certain
operations to the network controller. This improves the network throughput.
Interrupt coalesce settings
By using interrupt coalescing, the system collects network packets and generates a single interrupt
for multiple packets. This increases the amount of data sent to the kernel with one hardware
interrupt, which reduces the interrupt load, and maximizes the throughput.
Ring buffers
These buffers store incoming and outgoing network packets. You can increase the ring buffer sizes
to reduce a high packet drop rate.
Channel settings
A network interface manages its associated number of channels along with hardware settings and
network drivers. All devices associated with a network interface communicate with each other
through interrupt requests (IRQ). Each device queue holds pending IRQ and communicates with
each other over a data line known as channel. Types of queues are associated with specific channel
types. These channel types include:
rx for receiving queues
tx for transmit queues
other for link interrupts or single root input/output virtualization (SR-IOV) coordination
combined for hardware capacity-based multipurpose channels
29.1. CONFIGURING AN ETHTOOL OFFLOAD FEATURE BY USING NMCLI
You can use NetworkManager to enable and disable ethtool offload features in a connection profile.
Procedure
1. For example, to enable the RX offload feature and disable TX offload in the enp1s0 connection
profile, enter:
# nmcli con modify enp1s0 ethtool.feature-rx on ethtool.feature-tx off
This command explicitly enables RX offload and disables TX offload.
2. To remove the setting of an offload feature that you previously enabled or disabled, set the
feature’s parameter to a null value. For example, to remove the configuration for TX offload,
enter:
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# nmcli con modify enp1s0 ethtool.feature-tx ""
3. Reactivate the network profile:
# nmcli connection up enp1s0
Verification
Use the ethtool -k command to display the current offload features of a network device:
# ethtool -k network_device
Additional resources
nm-settings-nmcli(5) man page
29.2. CONFIGURING AN ETHTOOL OFFLOAD FEATURE BY USING THE
NETWORK RHEL SYSTEM ROLE
Network interface controllers can use the TCP offload engine (TOE) to offload processing certain
operations to the network controller. This improves the network throughput. You configure offload
features in the connection profile of the network interface. By using Ansible and the network RHEL
system role, you can automate this process and remotely configure connection profiles on the hosts
defined in a playbook.
WARNING
You cannot use the network RHEL system role to update only specific values in an
existing connection profile. The role ensures that a connection profile exactly
matches the settings in a playbook. If a connection profile with the same name
already exists, the role applies the settings from the playbook and resets all other
settings in the profile to their defaults. To prevent resetting values, always specify
the whole configuration of the network connection profile in the playbook, including
the settings that you do not want to change.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
---
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The settings specified in the example playbook include the following:
gro: no
Disables Generic receive offload (GRO).
gso: yes
Enables Generic segmentation offload (GSO).
tx_sctp_segmentation: no
Disables TX stream control transmission protocol (SCTP) segmentation.
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
Query the Ansible facts of the managed node and verify the offload settings:
# ansible managed-node-01.example.com -m ansible.builtin.setup
...
"ansible_enp1s0": {
"active": true,
"device": "enp1s0",
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: Ethernet connection profile with dynamic IP address settings and offload features
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
- name: enp1s0
type: ethernet
autoconnect: yes
ip:
dhcp4: yes
auto6: yes
ethtool:
features:
gro: no
gso: yes
tx_sctp_segmentation: no
state: up
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"features": {
...
"rx_gro_hw": "off,
...
"tx_gso_list": "on,
...
"tx_sctp_segmentation": "off",
...
}
...
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
29.3. CONFIGURING AN ETHTOOL COALESCE SETTINGS BY USING
NMCLI
You can use NetworkManager to set ethtool coalesce settings in connection profiles.
Procedure
1. For example, to set the maximum number of received packets to delay to 128 in the enp1s0
connection profile, enter:
# nmcli connection modify enp1s0 ethtool.coalesce-rx-frames 128
2. To remove a coalesce setting, set it to a null value. For example, to remove the
ethtool.coalesce-rx-frames setting, enter:
# nmcli connection modify enp1s0 ethtool.coalesce-rx-frames ""
3. To reactivate the network profile:
# nmcli connection up enp1s0
Verification
1. Use the ethtool -c command to display the current offload features of a network device:
# ethtool -c network_device
Additional resources
nm-settings-nmcli(5) man page
29.4. CONFIGURING AN ETHTOOL COALESCE SETTINGS BY USING THE
NETWORK RHEL SYSTEM ROLE
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By using interrupt coalescing, the system collects network packets and generates a single interrupt for
multiple packets. This increases the amount of data sent to the kernel with one hardware interrupt, which
reduces the interrupt load, and maximizes the throughput. You configure coalesce settings in the
connection profile of the network interface. By using Ansible and the network RHEL role, you can
automate this process and remotely configure connection profiles on the hosts defined in a playbook.
WARNING
You cannot use the network RHEL system role to update only specific values in an
existing connection profile. The role ensures that a connection profile exactly
matches the settings in a playbook. If a connection profile with the same name
already exists, the role applies the settings from the playbook and resets all other
settings in the profile to their defaults. To prevent resetting values, always specify
the whole configuration of the network connection profile in the playbook, including
the settings that you do not want to change.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
The settings specified in the example playbook include the following:
---
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: Ethernet connection profile with dynamic IP address settings and coalesce
settings
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
- name: enp1s0
type: ethernet
autoconnect: yes
ip:
dhcp4: yes
auto6: yes
ethtool:
coalesce:
rx_frames: 128
tx_frames: 128
state: up
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rx_frames: <value>
Sets the number of RX frames.
gso: <value>
Sets the number of TX frames.
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
$ ansible-playbook ~/playbook.yml
Verification
Display the current offload features of the network device:
# ansible managed-node-01.example.com -m command -a 'ethtool -c enp1s0'
managed-node-01.example.com | CHANGED | rc=0 >>
...
rx-frames: 128
...
tx-frames: 128
...
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
29.5. INCREASING THE RING BUFFER SIZE TO REDUCE A HIGH
PACKET DROP RATE BY USING NMCLI
Increase the size of an Ethernet device’s ring buffers if the packet drop rate causes applications to
report a loss of data, timeouts, or other issues.
Receive ring buffers are shared between the device driver and network interface controller (NIC). The
card assigns a transmit (TX) and receive (RX) ring buffer. As the name implies, the ring buffer is a
circular buffer where an overflow overwrites existing data. There are two ways to move data from the
NIC to the kernel, hardware interrupts and software interrupts, also called SoftIRQs.
The kernel uses the RX ring buffer to store incoming packets until the device driver can process them.
The device driver drains the RX ring, typically by using SoftIRQs, which puts the incoming packets into a
kernel data structure called an sk_buff or skb to begin its journey through the kernel and up to the
application that owns the relevant socket.
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The kernel uses the TX ring buffer to hold outgoing packets which should be sent to the network. These
ring buffers reside at the bottom of the stack and are a crucial point at which packet drop can occur,
which in turn will adversely affect network performance.
Procedure
1. Display the packet drop statistics of the interface:
# ethtool -S enp1s0
...
rx_queue_0_drops: 97326
rx_queue_1_drops: 63783
...
Note that the output of the command depends on the network card and the driver.
High values in discard or drop counters indicate that the available buffer fills up faster than the
kernel can process the packets. Increasing the ring buffers can help to avoid such loss.
2. Display the maximum ring buffer sizes:
# ethtool -g enp1s0
Ring parameters for enp1s0:
Pre-set maximums:
RX: 4096
RX Mini: 0
RX Jumbo: 16320
TX: 4096
Current hardware settings:
RX: 255
RX Mini: 0
RX Jumbo: 0
TX: 255
If the values in the Pre-set maximums section are higher than in the Current hardware
settings section, you can change the settings in the next steps.
3. Identify the NetworkManager connection profile that uses the interface:
# nmcli connection show
NAME UUID TYPE DEVICE
Example-Connection a5eb6490-cc20-3668-81f8-0314a27f3f75 ethernet enp1s0
4. Update the connection profile, and increase the ring buffers:
To increase the RX ring buffer, enter:
# nmcli connection modify Example-Connection ethtool.ring-rx 4096
To increase the TX ring buffer, enter:
# nmcli connection modify Example-Connection ethtool.ring-tx 4096
5. Reload the NetworkManager connection:
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289
# nmcli connection up Example-Connection
IMPORTANT
Depending on the driver your NIC uses, changing in the ring buffer can shortly
interrupt the network connection.
Additional resources
ifconfig and ip commands report packet drops
Should I be concerned about a 0.05% packet drop rate?
ethtool(8) man page
29.6. INCREASING THE RING BUFFER SIZE TO REDUCE A HIGH
PACKET DROP RATE BY USING THE NETWORK RHEL SYSTEM ROLE
Increase the size of an Ethernet device’s ring buffers if the packet drop rate causes applications to
report a loss of data, timeouts, or other issues.
Ring buffers are circular buffers where an overflow overwrites existing data. The network card assigns a
transmit (TX) and receive (RX) ring buffer. Receive ring buffers are shared between the device driver
and the network interface controller (NIC). Data can move from NIC to the kernel through either
hardware interrupts or software interrupts, also called SoftIRQs.
The kernel uses the RX ring buffer to store incoming packets until the device driver can process them.
The device driver drains the RX ring, typically by using SoftIRQs, which puts the incoming packets into a
kernel data structure called an sk_buff or skb to begin its journey through the kernel and up to the
application that owns the relevant socket.
The kernel uses the TX ring buffer to hold outgoing packets which should be sent to the network. These
ring buffers reside at the bottom of the stack and are a crucial point at which packet drop can occur,
which in turn will adversely affect network performance.
You configure ring buffer settings in the NetworkManager connection profiles. By using Ansible and the
network RHEL system role, you can automate this process and remotely configure connection profiles
on the hosts defined in a playbook.
WARNING
You cannot use the network RHEL system role to update only specific values in an
existing connection profile. The role ensures that a connection profile exactly
matches the settings in a playbook. If a connection profile with the same name
already exists, the role applies the settings from the playbook and resets all other
settings in the profile to their defaults. To prevent resetting values, always specify
the whole configuration of the network connection profile in the playbook, including
the settings that you do not want to change.
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Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
You know the maximum ring buffer sizes that the device supports.
Procedure
1. Create a playbook file, for example ~/playbook.yml, with the following content:
The settings specified in the example playbook include the following:
rx: <value>
Sets the maximum number of received ring buffer entries.
tx: <value>
Sets the maximum number of transmitted ring buffer entries.
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
2. Validate the playbook syntax:
$ ansible-playbook --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
3. Run the playbook:
---
- name: Configure the network
hosts: managed-node-01.example.com
tasks:
- name: Ethernet connection profile with dynamic IP address setting and increased ring
buffer sizes
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
- name: enp1s0
type: ethernet
autoconnect: yes
ip:
dhcp4: yes
auto6: yes
ethtool:
ring:
rx: 4096
tx: 4096
state: up
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$ ansible-playbook ~/playbook.yml
Verification
Display the maximum ring buffer sizes:
# ansible managed-node-01.example.com -m command -a 'ethtool -g enp1s0'
managed-node-01.example.com | CHANGED | rc=0 >>
...
Current hardware settings:
RX: 4096
RX Mini: 0
RX Jumbo: 0
TX: 4096
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
29.7. CONFIGURING AN ETHTOOL CHANNELS SETTINGS BY USING
NMCLI
By using NetworkManager, you can manage network devices and connections. The ethtool utility
manages the link speed and related settings of a network interface card. ethtool handles IRQ based
communication with associated devices to manage related channels settings in connection profiles.
Procedure
1. Display the channels associated with a network device:
# ethtool --show-channels enp1s0
Channel parameters for enp1s0:
Pre-set maximums:
RX: 4
TX: 3
Other: 10
Combined: 63
Current hardware settings:
RX: 1
TX: 1
Other: 1
Combined: 1
2. Update the channel settings of a network interface:
# nmcli connection modify enp1s0 ethtool.channels-rx 4 ethtool.channels-tx 3
ethtools.channels-other 9 ethtool.channels-combined 50
3. Reactivate the network profile:
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# nmcli connection up enp1s0
Verification
Check the updated channel settings associated with the network device:
# ethtool --show-channels enp1s0
Channel parameters for enp1s0:
Pre-set maximums:
RX: 4
TX: 3
Other: 10
Combined: 63
Current hardware settings:
RX: 4
TX: 3
Other: 9
Combined: 50
Additional resources
The nmcli(5) man page
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CHAPTER 30. INTRODUCTION TO NETWORKMANAGER
DEBUGGING
Increasing the log levels for all or certain domains helps to log more details of the operations that
NetworkManager performs. You can use this information to troubleshoot problems. NetworkManager
provides different levels and domains to produce logging information. The
/etc/NetworkManager/NetworkManager.conf file is the main configuration file for NetworkManager.
The logs are stored in the journal.
30.1. INTRODUCTION TO NETWORKMANAGER REAPPLY METHOD
The NetworkManager service uses a profile to manage the connection settings of a device. Desktop
Bus (D-Bus) API can create, modify, and delete these connection settings. For any changes in a profile,
D-Bus API clones the existing settings to the modified settings of a connection. Despite cloning,
changes do not apply to the modified settings. To make it effective, reactivate the existing settings of a
connection or use the reapply() method.
The reapply() method has the following features:
1. Updating modified connection settings without deactivation or restart of a network interface.
2. Removing pending changes from the modified connection settings. As NetworkManager does
not revert the manual changes, you can reconfigure the device and revert external or manual
parameters.
3. Creating different modified connection settings than that of the existing connection settings.
Also, reapply() method supports the following attributes:
bridge.ageing-time
bridge.forward-delay
bridge.group-address
bridge.group-forward-mask
bridge.hello-time
bridge.max-age
bridge.multicast-hash-max
bridge.multicast-last-member-count
bridge.multicast-last-member-interval
bridge.multicast-membership-interval
bridge.multicast-querier
bridge.multicast-querier-interval
bridge.multicast-query-interval
bridge.multicast-query-response-interval
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bridge.multicast-query-use-ifaddr
bridge.multicast-router
bridge.multicast-snooping
bridge.multicast-startup-query-count
bridge.multicast-startup-query-interval
bridge.priority
bridge.stp
bridge.VLAN-filtering
bridge.VLAN-protocol
bridge.VLANs
802-3-ethernet.accept-all-mac-addresses
802-3-ethernet.cloned-mac-address
IPv4.addresses
IPv4.dhcp-client-id
IPv4.dhcp-iaid
IPv4.dhcp-timeout
IPv4.DNS
IPv4.DNS-priority
IPv4.DNS-search
IPv4.gateway
IPv4.ignore-auto-DNS
IPv4.ignore-auto-routes
IPv4.may-fail
IPv4.method
IPv4.never-default
IPv4.route-table
IPv4.routes
IPv4.routing-rules
IPv6.addr-gen-mode
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IPv6.addresses
IPv6.dhcp-duid
IPv6.dhcp-iaid
IPv6.dhcp-timeout
IPv6.DNS
IPv6.DNS-priority
IPv6.DNS-search
IPv6.gateway
IPv6.ignore-auto-DNS
IPv6.may-fail
IPv6.method
IPv6.never-default
IPv6.ra-timeout
IPv6.route-metric
IPv6.route-table
IPv6.routes
IPv6.routing-rules
Additional resources
nm-settings-nmcli(5) man page
30.2. SETTING THE NETWORKMANAGER LOG LEVEL
By default, all the log domains are set to record the INFO log level. Disable rate-limiting before
collecting debug logs. With rate-limiting, systemd-journald drops messages if there are too many of
them in a short time. This can occur when the log level is TRACE.
This procedure disables rate-limiting and enables recording debug logs for the all (ALL) domains.
Procedure
1. To disable rate-limiting, edit the /etc/systemd/journald.conf file, uncomment the
RateLimitBurst parameter in the [Journal] section, and set its value as 0:
RateLimitBurst=0
2. Restart the systemd-journald service.
# systemctl restart systemd-journald
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3. Create the /etc/NetworkManager/conf.d/95-nm-debug.conf file with the following content:
[logging]
domains=ALL:TRACE
The domains parameter can contain multiple comma-separated domain:level pairs.
4. Restart the NetworkManager service.
# systemctl restart NetworkManager
Verification
Query the systemd journal to display the journal entries of the NetworkManager unit:
# journalctl -u NetworkManager
...
Jun 30 15:24:32 server NetworkManager[164187]: <debug> [1656595472.4939] active-
connection[0x5565143c80a0]: update activation type from assume to managed
Jun 30 15:24:32 server NetworkManager[164187]: <trace> [1656595472.4939]
device[55b33c3bdb72840c] (enp1s0): sys-iface-state: assume -> managed
Jun 30 15:24:32 server NetworkManager[164187]: <trace> [1656595472.4939]
l3cfg[4281fdf43e356454,ifindex=3]: commit type register (type "update", source "device",
existing a369f23014b9ede3) -> a369f23014b9ede3
Jun 30 15:24:32 server NetworkManager[164187]: <info> [1656595472.4940] manager:
NetworkManager state is now CONNECTED_SITE
...
30.3. TEMPORARILY SETTING LOG LEVELS AT RUN TIME USING NMCLI
You can change the log level at run time using nmcli.
Procedure
1. Optional: Display the current logging settings:
# nmcli general logging
LEVEL DOMAINS
INFO
PLATFORM,RFKILL,ETHER,WIFI,BT,MB,DHCP4,DHCP6,PPP,WIFI_SCAN,IP4,IP6,A
UTOIP4,DNS,VPN,SHARING,SUPPLICANT,AGENTS,SETTINGS,SUSPEND,CORE,DEVIC
E,OLPC,
WIMAX,INFINIBAND,FIREWALL,ADSL,BOND,VLAN,BRIDGE,DBUS_PROPS,TEAM,CONC
HECK,DC
B,DISPATCH
2. To modify the logging level and domains, use the following options:
To set the log level for all domains to the same LEVEL, enter:
# nmcli general logging level LEVEL domains ALL
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To change the level for specific domains, enter:
# nmcli general logging level LEVEL domains DOMAINS
Note that updating the logging level using this command disables logging for all the other
domains.
To change the level of specific domains and preserve the level of all other domains, enter:
# nmcli general logging level KEEP domains DOMAIN:LEVEL,DOMAIN:LEVEL
30.4. VIEWING NETWORKMANAGER LOGS
You can view the NetworkManager logs for troubleshooting.
Procedure
To view the logs, enter:
# journalctl -u NetworkManager -b
Additional resources
NetworkManager.conf(5) man page
journalctl(1) man page
30.5. DEBUGGING LEVELS AND DOMAINS
You can use the levels and domains parameters to manage the debugging for NetworkManager. The
level defines the verbosity level, whereas the domains define the category of the messages to record
the logs with given severity (level).
Log levels Description
OFF Does not log any messages about NetworkManager
ERR Logs only critical errors
WARN Logs warnings that can reflect the operation
INFO Logs various informational messages that are useful for tracking state and
operations
DEBUG Enables verbose logging for debugging purposes
TRACE Enables more verbose logging than the DEBUG level
Note that subsequent levels log all messages from earlier levels. For example, setting the log level to
INFO also logs messages contained in the ERR and WARN log level.
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Additional resources
NetworkManager.conf(5) man page
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CHAPTER 31. USING LLDP TO DEBUG NETWORK
CONFIGURATION PROBLEMS
You can use the Link Layer Discovery Protocol (LLDP) to debug network configuration problems in the
topology. This means that, LLDP can report configuration inconsistencies with other hosts or routers
and switches.
31.1. DEBUGGING AN INCORRECT VLAN CONFIGURATION USING
LLDP INFORMATION
If you configured a switch port to use a certain VLAN and a host does not receive these VLAN packets,
you can use the Link Layer Discovery Protocol (LLDP) to debug the problem. Perform this procedure on
the host that does not receive the packets.
Prerequisites
The nmstate package is installed.
The switch supports LLDP.
LLDP is enabled on neighbor devices.
Procedure
1. Create the ~/enable-LLDP-enp1s0.yml file with the following content:
2. Use the ~/enable-LLDP-enp1s0.yml file to enable LLDP on interface enp1s0:
# nmstatectl apply ~/enable-LLDP-enp1s0.yml
3. Display the LLDP information:
# nmstatectl show enp1s0
- name: enp1s0
type: ethernet
state: up
ipv4:
enabled: false
dhcp: false
ipv6:
enabled: false
autoconf: false
dhcp: false
lldp:
enabled: true
neighbors:
- - type: 5
interfaces:
- name: enp1s0
type: ethernet
lldp:
enabled: true
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system-name: Summit300-48
- type: 6
system-description: Summit300-48 - Version 7.4e.1 (Build 5)
05/27/05 04:53:11
- type: 7
system-capabilities:
- MAC Bridge component
- Router
- type: 1
_description: MAC address
chassis-id: 00:01:30:F9:AD:A0
chassis-id-type: 4
- type: 2
_description: Interface name
port-id: 1/1
port-id-type: 5
- type: 127
ieee-802-1-vlans:
- name: v2-0488-03-0505
vid: 488
oui: 00:80:c2
subtype: 3
- type: 127
ieee-802-3-mac-phy-conf:
autoneg: true
operational-mau-type: 16
pmd-autoneg-cap: 27648
oui: 00:12:0f
subtype: 1
- type: 127
ieee-802-1-ppvids:
- 0
oui: 00:80:c2
subtype: 2
- type: 8
management-addresses:
- address: 00:01:30:F9:AD:A0
address-subtype: MAC
interface-number: 1001
interface-number-subtype: 2
- type: 127
ieee-802-3-max-frame-size: 1522
oui: 00:12:0f
subtype: 4
mac-address: 82:75:BE:6F:8C:7A
mtu: 1500
4. Verify the output to ensure that the settings match your expected configuration. For example,
the LLDP information of the interface connected to the switch shows that the switch port this
host is connected to uses VLAN ID 448:
If the network configuration of the enp1s0 interface uses a different VLAN ID, change it
- type: 127
ieee-802-1-vlans:
- name: v2-0488-03-0505
vid: 488
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CHAPTER 32. LINUX TRAFFIC CONTROL
Linux offers tools for managing and manipulating the transmission of packets. The Linux Traffic Control
(TC) subsystem helps in policing, classifying, shaping, and scheduling network traffic. TC also mangles
the packet content during classification by using filters and actions. The TC subsystem achieves this by
using queuing disciplines (qdisc), a fundamental element of the TC architecture.
The scheduling mechanism arranges or rearranges the packets before they enter or exit different
queues. The most common scheduler is the First-In-First-Out (FIFO) scheduler. You can do the qdiscs
operations temporarily using the tc utility or permanently using NetworkManager.
In Red Hat Enterprise Linux, you can configure default queueing disciplines in various ways to manage
the traffic on a network interface.
32.1. OVERVIEW OF QUEUING DISCIPLINES
Queuing disciplines (qdiscs) help with queuing up and, later, scheduling of traffic transmission by a
network interface. A qdisc has two operations;
enqueue requests so that a packet can be queued up for later transmission and
dequeue requests so that one of the queued-up packets can be chosen for immediate
transmission.
Every qdisc has a 16-bit hexadecimal identification number called a handle, with an attached colon, such
as 1: or abcd:. This number is called the qdisc major number. If a qdisc has classes, then the identifiers
are formed as a pair of two numbers with the major number before the minor, <major>:<minor>, for
example abcd:1. The numbering scheme for the minor numbers depends on the qdisc type. Sometimes
the numbering is systematic, where the first-class has the ID <major>:1, the second one <major>:2, and
so on. Some qdiscs allow the user to set class minor numbers arbitrarily when creating the class.
Classful qdiscs
Different types of qdiscs exist and help in the transfer of packets to and from a networking
interface. You can configure qdiscs with root, parent, or child classes. The point where children can
be attached are called classes. Classes in qdisc are flexible and can always contain either multiple
children classes or a single child, qdisc. There is no prohibition against a class containing a classful
qdisc itself, this facilitates complex traffic control scenarios.
Classful qdiscs do not store any packets themselves. Instead, they enqueue and dequeue requests
down to one of their children according to criteria specific to the qdisc. Eventually, this recursive
packet passing ends up where the packets are stored (or picked up from in the case of dequeuing).
Classless qdiscs
Some qdiscs contain no child classes and they are called classless qdiscs. Classless qdiscs require
less customization compared to classful qdiscs. It is usually enough to attach them to an interface.
Additional resources
tc(8) man page
tc-actions(8) man page
32.2. INTRODUCTION TO CONNECTION TRACKING
At a firewall, the Netfilter framework filters packets from an external network. After a packet arrives,
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Netfilter assigns a connection tracking entry. Connection tracking is a Linux kernel networking feature
for logical networks that tracks connections and identifies packet flow in those connections. This feature
filters and analyzes every packet, sets up the connection tracking table to store connection status, and
updates the connection status based on identified packets. For example, in the case of FTP connection,
Netfilter assigns a connection tracking entry to ensure all packets of FTP connection work in the same
manner. The connection tracking entry stores a Netfilter mark and tracks the connection state
information in the memory table in which a new packet tuple maps with an existing entry. If the packet
tuple does not map with an existing entry, the packet adds a new connection tracking entry that groups
packets of the same connection.
You can control and analyze traffic on the network interface. The tc traffic controller utility uses the
qdisc discipline to configure the packet scheduler in the network. The qdisc kernel-configured queuing
discipline enqueues packets to the interface. By using qdisc, Kernel catches all the traffic before a
network interface transmits it. Also, to limit the bandwidth rate of packets belonging to the same
connection, use the tc qdisc command.
To retrieve data from connection tracking marks into various fields, use the tc utility with the ctinfo
module and the connmark functionality. For storing packet mark information, the ctinfo module copies
the Netfilter mark and the connection state information into a socket buffer ( skb) mark metadata field.
Transmitting a packet over a physical medium removes all the metadata of a packet. Before the packet
loses its metadata, the ctinfo module maps and copies the Netfilter mark value to a specific value of the
Diffserv code point (DSCP) in the packet’s IP field.
Additional resources
tc(8) and tc-ctinfo(8) man pages
32.3. INSPECTING QDISCS OF A NETWORK INTERFACE USING THE TC
UTILITY
By default, Red Hat Enterprise Linux systems use fq_codel qdisc. You can inspect the qdisc counters
using the tc utility.
Procedure
1. Optional: View your current qdisc:
# tc qdisc show dev enp0s1
2. Inspect the current qdisc counters:
# tc -s qdisc show dev enp0s1
qdisc fq_codel 0: root refcnt 2 limit 10240p flows 1024 quantum 1514 target 5.0ms interval
100.0ms memory_limit 32Mb ecn
Sent 1008193 bytes 5559 pkt (dropped 233, overlimits 55 requeues 77)
backlog 0b 0p requeues 0
dropped - the number of times a packet is dropped because all queues are full
overlimits - the number of times the configured link capacity is filled
sent - the number of dequeues
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32.4. UPDATING THE DEFAULT QDISC
If you observe networking packet losses with the current qdisc, you can change the qdisc based on your
network-requirements.
Procedure
1. View the current default qdisc:
# sysctl -a | grep qdisc
net.core.default_qdisc = fq_codel
2. View the qdisc of current Ethernet connection:
# tc -s qdisc show dev enp0s1
qdisc fq_codel 0: root refcnt 2 limit 10240p flows 1024 quantum 1514 target 5.0ms interval
100.0ms memory_limit 32Mb ecn
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
maxpacket 0 drop_overlimit 0 new_flow_count 0 ecn_mark 0
new_flows_len 0 old_flows_len 0
3. Update the existing qdisc:
# sysctl -w net.core.default_qdisc=pfifo_fast
4. To apply the changes, reload the network driver:
# modprobe -r NETWORKDRIVERNAME
# modprobe NETWORKDRIVERNAME
5. Start the network interface:
# ip link set enp0s1 up
Verification
View the qdisc of the Ethernet connection:
# tc -s qdisc show dev enp0s1
qdisc pfifo_fast 0: root refcnt 2 bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
Sent 373186 bytes 5333 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
....
Additional resources
How to set sysctl variables on Red Hat Enterprise Linux
32.5. TEMPORARILY SETTING THE CURRENT QDISC OF A NETWORK
INTERFACE USING THE TC UTILITY
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305
You can update the current qdisc without changing the default one.
Procedure
1. Optional: View the current qdisc:
# tc -s qdisc show dev enp0s1
2. Update the current qdisc:
# tc qdisc replace dev enp0s1 root htb
Verification
View the updated current qdisc:
# tc -s qdisc show dev enp0s1
qdisc htb 8001: root refcnt 2 r2q 10 default 0 direct_packets_stat 0 direct_qlen 1000
Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
32.6. PERMANENTLY SETTING THE CURRENT QDISC OF A NETWORK
INTERFACE USING NETWORKMANAGER
You can update the current qdisc value of a NetworkManager connection.
Procedure
1. Optional: View the current qdisc:
# tc qdisc show dev enp0s1
qdisc fq_codel 0: root refcnt 2
2. Update the current qdisc:
# nmcli connection modify enp0s1 tc.qdiscs 'root pfifo_fast'
3. Optional: To add another qdisc over the existing qdisc, use the +tc.qdisc option:
# nmcli connection modify enp0s1 +tc.qdisc 'ingress handle ffff:'
4. Activate the changes:
# nmcli connection up enp0s1
Verification
View current qdisc the network interface:
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# tc qdisc show dev enp0s1
qdisc pfifo_fast 8001: root refcnt 2 bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
qdisc ingress ffff: parent ffff:fff1 ----------------
Additional resources
nm-settings(5) man page
32.7. CONFIGURING THE RATE LIMITING OF PACKETS BY USING THE
TC-CTINFO UTILITY
You can limit network traffic and prevent the exhaustion of resources in the network by using rate
limiting. With rate limiting, you can also reduce the load on servers by limiting repetitive packet requests
in a specific time frame. In addition, you can manage bandwidth rate by configuring traffic control in the
kernel with the tc-ctinfo utility.
The connection tracking entry stores the Netfilter mark and connection information. When a router
forwards a packet from the firewall, the router either removes or modifies the connection tracking entry
from the packet. The connection tracking information (ctinfo) module retrieves data from connection
tracking marks into various fields. This kernel module preserves the Netfilter mark by copying it into
socket buffer (skb) mark metadata field.
Prerequisites
The iperf3 utility is installed on a server and a client.
Procedure
1. Perform the following steps on the server:
a. Add a virtual link to the network interface:
# ip link add name ifb4eth0 numtxqueues 48 numrxqueues 48 type ifb
This command has the following parameters:
name ifb4eth0
Sets new virtual device interface.
numtxqueues 48
Sets the number of transmit queues.
numrxqueues 48
Sets the number of receive queues.
type ifb
Sets the type of the new device.
b. Change the state of the interface:
# ip link set dev ifb4eth0 up
c. Add the qdisc attribute on the physical network interface and apply it to the incoming
traffic:
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307
# tc qdisc add dev enp1s0 handle ffff: ingress
In the handle ffff: option, the handle parameter assigns the major number ffff: as a default
value to a classful qdisc on the enp1s0 physical network interface, where qdisc is a
queueing discipline parameter to analyze traffic control.
d. Add a filter on the physical interface of the ip protocol to classify packets:
# tc filter add dev enp1s0 parent ffff: protocol ip u32 match u32 0 0 action ctinfo
cpmark 100 action mirred egress redirect dev ifb4eth0
This command has the following attributes:
parent ffff:
Sets major number ffff: for the parent qdisc.
u32 match u32 0 0
Sets the u32 filter to match the IP headers of u32 pattern. The first 0 represents the
second byte of IP header while the other 0 is for the mask match telling the filter which
bits to match.
action ctinfo
Sets action to retrieve data from the connection tracking mark into various fields.
cpmark 100
Copies the connection tracking mark (connmark) 100 into the packet IP header field.
action mirred egress redirect dev ifb4eth0
Sets action mirred to redirect the received packets to the ifb4eth0 destination
interface.
e. Add a classful qdisc to the interface:
# tc qdisc add dev ifb4eth0 root handle 1: htb default 1000
This command sets the major number 1 to root qdisc and uses the htb hierarchy token
bucket with classful qdisc of minor-id 1000.
f. Limit the traffic on the interface to 1 Mbit/s with an upper limit of 2 Mbit/s:
# tc class add dev ifb4eth0 parent 1:1 classid 1:100 htb ceil 2mbit rate 1mbit prio
100
This command has the following parameters:
parent 1:1
Sets parent with classid as 1 and root as 1.
classid 1:100
Sets classid as 1:100 where 1 is the number of parent qdisc and 100 is the number of
classes of the parent qdisc.
htb ceil 2mbit
The htb classful qdisc allows upper limit bandwidth of 2 Mbit/s as the ceil rate limit.
g. Apply the Stochastic Fairness Queuing (sfq) of classless qdisc to interface with a time
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g. Apply the Stochastic Fairness Queuing (sfq) of classless qdisc to interface with a time
interval of 60 seconds to reduce queue algorithm perturbation:
# tc qdisc add dev ifb4eth0 parent 1:100 sfq perturb 60
h. Add the firewall mark (fw) filter to the interface:
# tc filter add dev ifb4eth0 parent 1:0 protocol ip prio 100 handle 100 fw classid
1:100
i. Restore the packet meta mark from the connection mark (CONNMARK):
# nft add rule ip mangle PREROUTING counter meta mark set ct mark
In this command, the nft utility has a mangle table with the PREROUTING chain rule
specification that alters incoming packets before routing to replace the packet mark with
CONNMARK.
j. If no nft table and chain exist, create a table and add a chain rule:
# nft add table ip mangle
# nft add chain ip mangle PREROUTING {type filter hook prerouting priority
mangle \;}
k. Set the meta mark on tcp packets that are received on the specified destination address
192.0.2.3:
# nft add rule ip mangle PREROUTING ip daddr 192.0.2.3 counter meta mark set
0x64
l. Save the packet mark into the connection mark:
# nft add rule ip mangle PREROUTING counter ct mark set mark
m. Run the iperf3 utility as the server on a system by using the -s parameter and the server
then waits for the response of the client connection:
# iperf3 -s
2. On the client, run iperf3 as a client and connect to the server that listens on IP address
192.0.2.3 for periodic HTTP request-response timestamp:
# iperf3 -c 192.0.2.3 -t TCP_STREAM | tee rate
192.0.2.3 is the IP address of the server while 192.0.2.4 is the IP address of the client.
3. Terminate the iperf3 utility on the server by pressing Ctrl+C:
Accepted connection from 192.0.2.4, port 52128
[5] local 192.0.2.3 port 5201 connected to 192.0.2.4 port 52130
[ID] Interval Transfer Bitrate
[5] 0.00-1.00 sec 119 KBytes 973 Kbits/sec
[5] 1.00-2.00 sec 116 KBytes 950 Kbits/sec
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309
...
[ID] Interval Transfer Bitrate
[5] 0.00-14.81 sec 1.51 MBytes 853 Kbits/sec receiver
iperf3: interrupt - the server has terminated
4. Terminate the iperf3 utility on the client by pressing Ctrl+C:
Connecting to host 192.0.2.3, port 5201
[5] local 192.0.2.4 port 52130 connected to 192.0.2.3 port 5201
[ID] Interval Transfer Bitrate Retr Cwnd
[5] 0.00-1.00 sec 481 KBytes 3.94 Mbits/sec 0 76.4 KBytes
[5] 1.00-2.00 sec 223 KBytes 1.83 Mbits/sec 0 82.0 KBytes
...
[ID] Interval Transfer Bitrate Retr
[5] 0.00-14.00 sec 3.92 MBytes 2.35 Mbits/sec 32 sender
[5] 0.00-14.00 sec 0.00 Bytes 0.00 bits/sec receiver
iperf3: error - the server has terminated
Verification
1. Display the statistics about packet counts of the htb and sfq classes on the interface:
# tc -s qdisc show dev ifb4eth0
qdisc htb 1: root
...
Sent 26611455 bytes 3054 pkt (dropped 76, overlimits 4887 requeues 0)
...
qdisc sfq 8001: parent
...
Sent 26535030 bytes 2296 pkt (dropped 76, overlimits 0 requeues 0)
...
2. Display the statistics of packet counts for the mirred and ctinfo actions:
# tc -s filter show dev enp1s0 ingress
filter parent ffff: protocol ip pref 49152 u32 chain 0
filter parent ffff: protocol ip pref 49152 u32 chain 0 fh 800: ht divisor 1
filter parent ffff: protocol ip pref 49152 u32 chain 0 fh 800::800 order 2048 key ht 800 bkt 0
terminal flowid not_in_hw (rule hit 8075 success 8075)
match 00000000/00000000 at 0 (success 8075 )
action order 1: ctinfo zone 0 pipe
index 1 ref 1 bind 1 cpmark 0x00000064 installed 3105 sec firstused 3105 sec DSCP set
0 error 0
CPMARK set 7712
Action statistics:
Sent 25891504 bytes 3137 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0
action order 2: mirred (Egress Redirect to device ifb4eth0) stolen
index 1 ref 1 bind 1 installed 3105 sec firstused 3105 sec
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Action statistics:
Sent 25891504 bytes 3137 pkt (dropped 0, overlimits 61 requeues 0)
backlog 0b 0p requeues 0
3. Display the statistics of the htb rate-limiter and its configuration:
# tc -s class show dev ifb4eth0
class htb 1:100 root leaf 8001: prio 7 rate 1Mbit ceil 2Mbit burst 1600b cburst 1600b
Sent 26541716 bytes 2373 pkt (dropped 61, overlimits 4887 requeues 0)
backlog 0b 0p requeues 0
lended: 7248 borrowed: 0 giants: 0
tokens: 187250 ctokens: 93625
Additional resources
tc(8) and tc-ctinfo(8) man page
nft(8) man page
32.8. AVAILABLE QDISCS IN RHEL
Each qdisc addresses unique networking-related issues. The following is the list of qdiscs available in
RHEL. You can use any of the following qdisc to shape network traffic based on your networking
requirements.
Table 32.1. Available schedulers in RHEL
qdisc name Included in Offload support
Asynchronous Transfer Mode
(ATM)
kernel-modules-extra
Class-Based Queueing kernel-modules-extra
Credit-Based Shaper kernel-modules-extra Yes
CHOose and Keep for responsive
flows, CHOose and Kill for
unresponsive flows (CHOKE)
kernel-modules-extra
Controlled Delay (CoDel) kernel-core
Deficit Round Robin (DRR) kernel-modules-extra
Differentiated Services marker
(DSMARK)
kernel-modules-extra
Enhanced Transmission Selection
(ETS)
kernel-modules-extra Yes
Fair Queue (FQ) kernel-core
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311
Fair Queuing Controlled Delay
(FQ_CODel)
kernel-core
Generalized Random Early
Detection (GRED)
kernel-modules-extra
Hierarchical Fair Service Curve
(HSFC)
kernel-core
Heavy-Hitter Filter (HHF) kernel-core
Hierarchy Token Bucket (HTB) kernel-core
INGRESS kernel-core Yes
Multi Queue Priority (MQPRIO) kernel-modules-extra Yes
Multiqueue (MULTIQ) kernel-modules-extra Yes
Network Emulator (NETEM) kernel-modules-extra
Proportional Integral-controller
Enhanced (PIE)
kernel-core
PLUG kernel-core
Quick Fair Queueing (QFQ) kernel-modules-extra
Random Early Detection (RED) kernel-modules-extra Yes
Stochastic Fair Blue (SFB) kernel-modules-extra
Stochastic Fairness Queueing
(SFQ)
kernel-core
Token Bucket Filter (TBF) kernel-core Yes
Trivial Link Equalizer (TEQL) kernel-modules-extra
qdisc name Included in Offload support
IMPORTANT
The qdisc offload requires hardware and driver support on NIC.
Additional resources
tc(8) man page
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CHAPTER 33. AUTHENTICATING A RHEL CLIENT TO THE
NETWORK BY USING THE 802.1X STANDARD WITH A
CERTIFICATE STORED ON THE FILE SYSTEM
Administrators frequently use port-based Network Access Control (NAC) based on the IEEE 802.1X
standard to protect a network from unauthorized LAN and Wi-Fi clients. To enable a client to connect to
such networks, you must configure 802.1X authentication on this clients.
33.1. CONFIGURING 802.1X NETWORK AUTHENTICATION ON AN
EXISTING ETHERNET CONNECTION BY USING NMCLI
You can use the nmcli utility to configure an Ethernet connection with 802.1X network authentication
on the command line.
Prerequisites
The network supports 802.1X network authentication.
The Ethernet connection profile exists in NetworkManager and has a valid IP configuration.
The following files required for TLS authentication exist on the client:
The client key stored is in the /etc/pki/tls/private/client.key file, and the file is owned and
only readable by the root user.
The client certificate is stored in the /etc/pki/tls/certs/client.crt file.
The Certificate Authority (CA) certificate is stored in the /etc/pki/tls/certs/ca.crt file.
The wpa_supplicant package is installed.
Procedure
1. Set the Extensible Authentication Protocol (EAP) to tls and the paths to the client certificate
and key file:
# nmcli connection modify enp1s0 802-1x.eap tls 802-1x.client-cert
/etc/pki/tls/certs/client.crt 802-1x.private-key /etc/pki/tls/certs/certs/client.key
Note that you must set the 802-1x.eap, 802-1x.client-cert, and 802-1x.private-key parameters
in a single command.
2. Set the path to the CA certificate:
# nmcli connection modify enp1s0 802-1x.ca-cert /etc/pki/tls/certs/ca.crt
3. Set the identity of the user used in the certificate:
# nmcli connection modify enp1s0 802-1x.identity user@example.com
4. Optional: Store the password in the configuration:
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313
# nmcli connection modify enp1s0 802-1x.private-key-password password
IMPORTANT
By default, NetworkManager stores the password in clear text in the connection
profile on the disk, but the file is readable only by the root user. However, clear
text passwords in a configuration file can be a security risk.
To increase the security, set the 802-1x.password-flags parameter to 0x1. With
this setting, on servers with the GNOME desktop environment or the nm-applet
running, NetworkManager retrieves the password from these services. In other
cases, NetworkManager prompts for the password.
5. Activate the connection profile:
# nmcli connection up enp1s0
Verification
Access resources on the network that require network authentication.
Additional resources
Configuring an Ethernet connection
33.2. CONFIGURING A STATIC ETHERNET CONNECTION WITH 802.1X
NETWORK AUTHENTICATION BY USING NMSTATECTL
Use the nmstatectl utility to configure an Ethernet connection with 802.1X network authentication
through the Nmstate API. The Nmstate API ensures that, after setting the configuration, the result
matches the configuration file. If anything fails, nmstatectl automatically rolls back the changes to avoid
leaving the system in an incorrect state.
NOTE
The nmstate library only supports the TLS Extensible Authentication Protocol (EAP)
method.
Prerequisites
The network supports 802.1X network authentication.
The managed node uses NetworkManager.
The following files required for TLS authentication exist on the client:
The client key stored is in the /etc/pki/tls/private/client.key file, and the file is owned and
only readable by the root user.
The client certificate is stored in the /etc/pki/tls/certs/client.crt file.
The Certificate Authority (CA) certificate is stored in the /etc/pki/tls/certs/ca.crt file.
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Procedure
1. Create a YAML file, for example ~/create-ethernet-profile.yml, with the following content:
These settings define an Ethernet connection profile for the enp1s0 device with the following
settings:
A static IPv4 address - 192.0.2.1 with a /24 subnet mask
A static IPv6 address - 2001:db8:1::1 with a /64 subnet mask
An IPv4 default gateway - 192.0.2.254
An IPv6 default gateway - 2001:db8:1::fffe
---
interfaces:
- name: enp1s0
type: ethernet
state: up
ipv4:
enabled: true
address:
- ip: 192.0.2.1
prefix-length: 24
dhcp: false
ipv6:
enabled: true
address:
- ip: 2001:db8:1::1
prefix-length: 64
autoconf: false
dhcp: false
802.1x:
ca-cert: /etc/pki/tls/certs/ca.crt
client-cert: /etc/pki/tls/certs/client.crt
eap-methods:
- tls
identity: client.example.org
private-key: /etc/pki/tls/private/client.key
private-key-password: password
routes:
config:
- destination: 0.0.0.0/0
next-hop-address: 192.0.2.254
next-hop-interface: enp1s0
- destination: ::/0
next-hop-address: 2001:db8:1::fffe
next-hop-interface: enp1s0
dns-resolver:
config:
search:
- example.com
server:
- 192.0.2.200
- 2001:db8:1::ffbb
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315
An IPv4 DNS server - 192.0.2.200
An IPv6 DNS server - 2001:db8:1::ffbb
A DNS search domain - example.com
802.1X network authentication using the TLS EAP protocol
2. Apply the settings to the system:
# nmstatectl apply ~/create-ethernet-profile.yml
Verification
Access resources on the network that require network authentication.
33.3. CONFIGURING A STATIC ETHERNET CONNECTION WITH 802.1X
NETWORK AUTHENTICATION BY USING THE NETWORK
RHEL SYSTEM ROLE
Network Access Control (NAC) protects a network from unauthorized clients. You can specify the
details that are required for the authentication in NetworkManager connection profiles to enable clients
to access the network. By using Ansible and the network RHEL system role, you can automate this
process and remotely configure connection profiles on the hosts defined in a playbook.
You can use an Ansible playbook to copy a private key, a certificate, and the CA certificate to the client,
and then use the network RHEL system role to configure a connection profile with 802.1X network
authentication.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
The network supports 802.1X network authentication.
The managed nodes use NetworkManager.
The following files required for the TLS authentication exist on the control node:
The client key is stored in the /srv/data/client.key file.
The client certificate is stored in the /srv/data/client.crt file.
The Certificate Authority (CA) certificate is stored in the /srv/data/ca.crt file.
Procedure
1. Store your sensitive variables in an encrypted file:
a. Create the vault:
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$ ansible-vault create vault.yml
New Vault password: <vault_password>
Confirm New Vault password: <vault_password>
b. After the ansible-vault create command opens an editor, enter the sensitive data in the
<key>: <value> format:
c. Save the changes, and close the editor. Ansible encrypts the data in the vault.
2. Create a playbook file, for example ~/playbook.yml, with the following content:
pwd: <password>
---
- name: Configure an Ethernet connection with 802.1X authentication
hosts: managed-node-01.example.com
vars_files:
- vault.yml
tasks:
- name: Copy client key for 802.1X authentication
ansible.builtin.copy:
src: "/srv/data/client.key"
dest: "/etc/pki/tls/private/client.key"
mode: 0600
- name: Copy client certificate for 802.1X authentication
ansible.builtin.copy:
src: "/srv/data/client.crt"
dest: "/etc/pki/tls/certs/client.crt"
- name: Copy CA certificate for 802.1X authentication
ansible.builtin.copy:
src: "/srv/data/ca.crt"
dest: "/etc/pki/ca-trust/source/anchors/ca.crt"
- name: Ethernet connection profile with static IP address settings and 802.1X
ansible.builtin.include_role:
name: rhel-system-roles.network
vars:
network_connections:
- name: enp1s0
type: ethernet
autoconnect: yes
ip:
address:
- 192.0.2.1/24
- 2001:db8:1::1/64
gateway4: 192.0.2.254
gateway6: 2001:db8:1::fffe
dns:
- 192.0.2.200
- 2001:db8:1::ffbb
dns_search:
- example.com
ieee802_1x:
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The settings specified in the example playbook include the following:
ieee802_1x
This variable contains the 802.1X-related settings.
eap: tls
Configures the profile to use the certificate-based TLS authentication method for the
Extensible Authentication Protocol (EAP).
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
3. Validate the playbook syntax:
$ ansible-playbook --ask-vault-pass --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
4. Run the playbook:
$ ansible-playbook --ask-vault-pass ~/playbook.yml
Verification
Access resources on the network that require network authentication.
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
Ansible vault
33.4. CONFIGURING A WIFI CONNECTION WITH 802.1X NETWORK
AUTHENTICATION BY USING THE NETWORK RHEL SYSTEM ROLE
Network Access Control (NAC) protects a network from unauthorized clients. You can specify the
details that are required for the authentication in NetworkManager connection profiles to enable clients
to access the network. By using Ansible and the network RHEL system role, you can automate this
process and remotely configure connection profiles on the hosts defined in a playbook.
You can use an Ansible playbook to copy a private key, a certificate, and the CA certificate to the client,
identity: <user_name>
eap: tls
private_key: "/etc/pki/tls/private/client.key"
private_key_password: "{{ pwd }}"
client_cert: "/etc/pki/tls/certs/client.crt"
ca_cert: "/etc/pki/ca-trust/source/anchors/ca.crt"
domain_suffix_match: example.com
state: up
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You can use an Ansible playbook to copy a private key, a certificate, and the CA certificate to the client,
and then use the network RHEL system role to configure a connection profile with 802.1X network
authentication.
Prerequisites
You have prepared the control node and the managed nodes
You are logged in to the control node as a user who can run playbooks on the managed nodes.
The account you use to connect to the managed nodes has sudo permissions on them.
The network supports 802.1X network authentication.
You installed the wpa_supplicant package on the managed node.
DHCP is available in the network of the managed node.
The following files required for TLS authentication exist on the control node:
The client key is stored in the /srv/data/client.key file.
The client certificate is stored in the /srv/data/client.crt file.
The CA certificate is stored in the /srv/data/ca.crt file.
Procedure
1. Store your sensitive variables in an encrypted file:
a. Create the vault:
$ ansible-vault create vault.yml
New Vault password: <vault_password>
Confirm New Vault password: <vault_password>
b. After the ansible-vault create command opens an editor, enter the sensitive data in the
<key>: <value> format:
c. Save the changes, and close the editor. Ansible encrypts the data in the vault.
2. Create a playbook file, for example ~/playbook.yml, with the following content:
pwd: <password>
---
- name: Configure a wifi connection with 802.1X authentication
hosts: managed-node-01.example.com
tasks:
- name: Copy client key for 802.1X authentication
ansible.builtin.copy:
src: "/srv/data/client.key"
dest: "/etc/pki/tls/private/client.key"
mode: 0400
- name: Copy client certificate for 802.1X authentication
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The settings specified in the example playbook include the following:
ieee802_1x
This variable contains the 802.1X-related settings.
eap: tls
Configures the profile to use the certificate-based TLS authentication method for the
Extensible Authentication Protocol (EAP).
For details about all variables used in the playbook, see the /usr/share/ansible/roles/rhel-
system-roles.network/README.md file on the control node.
3. Validate the playbook syntax:
$ ansible-playbook --ask-vault-pass --syntax-check ~/playbook.yml
Note that this command only validates the syntax and does not protect against a wrong but valid
configuration.
4. Run the playbook:
ansible.builtin.copy:
src: "/srv/data/client.crt"
dest: "/etc/pki/tls/certs/client.crt"
- name: Copy CA certificate for 802.1X authentication
ansible.builtin.copy:
src: "/srv/data/ca.crt"
dest: "/etc/pki/ca-trust/source/anchors/ca.crt"
- name: Wifi connection profile with dynamic IP address settings and 802.1X
ansible.builtin.import_role:
name: rhel-system-roles.network
vars:
network_connections:
- name: Wifi connection profile with dynamic IP address settings and 802.1X
interface_name: wlp1s0
state: up
type: wireless
autoconnect: yes
ip:
dhcp4: true
auto6: true
wireless:
ssid: "Example-wifi"
key_mgmt: "wpa-eap"
ieee802_1x:
identity: <user_name>
eap: tls
private_key: "/etc/pki/tls/client.key"
private_key_password: "{{ pwd }}"
private_key_password_flags: none
client_cert: "/etc/pki/tls/client.pem"
ca_cert: "/etc/pki/tls/cacert.pem"
domain_suffix_match: "example.com"
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$ ansible-playbook --ask-vault-pass ~/playbook.yml
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
/usr/share/doc/rhel-system-roles/network/ directory
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CHAPTER 34. SETTING UP AN 802.1X NETWORK
AUTHENTICATION SERVICE FOR LAN CLIENTS BY USING
HOSTAPD WITH FREERADIUS BACKEND
The IEEE 802.1X standard defines secure authentication and authorization methods to protect networks
from unauthorized clients. By using the hostapd service and FreeRADIUS, you can provide network
access control (NAC) in your network.
In this documentation, the RHEL host acts as a bridge to connect different clients with an existing
network. However, the RHEL host grants only authenticated clients access to the network.
34.1. PREREQUISITES
A clean installation of the freeradius package.
If the package is already installed, remove the /etc/raddb/ directory, uninstall and then install
the package again. Do not reinstall the package by using the dnf reinstall command, because
the permissions and symbolic links in the /etc/raddb/ directory are then different.
34.2. SETTING UP THE BRIDGE ON THE AUTHENTICATOR
A network bridge is a link-layer device which forwards traffic between hosts and networks based on a
table of MAC addresses. If you set up RHEL as an 802.1X authenticator, add both the interfaces on
which to perform authentication and the LAN interface to the bridge.
Prerequisites
The server has multiple Ethernet interfaces.
Procedure
1. Create the bridge interface:
# nmcli connection add type bridge con-name br0 ifname br0
2. Assign the Ethernet interfaces to the bridge:
# nmcli connection add type ethernet port-type bridge con-name br0-port1 ifname
enp1s0 controller br0
# nmcli connection add type ethernet port-type bridge con-name br0-port2 ifname
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enp7s0 controller br0
# nmcli connection add type ethernet port-type bridge con-name br0-port3 ifname
enp8s0 controller br0
# nmcli connection add type ethernet port-type bridge con-name br0-port4 ifname
enp9s0 controller br0
3. Enable the bridge to forward extensible authentication protocol over LAN (EAPOL) packets:
# nmcli connection modify br0 group-forward-mask 8
4. Configure the connection to automatically activate the ports:
# nmcli connection modify br0 connection.autoconnect-ports 1
5. Activate the connection:
# nmcli connection up br0
Verification
1. Display the link status of Ethernet devices that are ports of a specific bridge:
# ip link show master br0
3: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel master
br0 state UP mode DEFAULT group default qlen 1000
link/ether 52:54:00:62:61:0e brd ff:ff:ff:ff:ff:ff
...
2. Verify if forwarding of EAPOL packets is enabled on the br0 device:
# cat /sys/class/net/br0/bridge/group_fwd_mask
0x8
If the command returns 0x8, forwarding is enabled.
Additional resources
nm-settings(5) man page
34.3. CERTIFICATE REQUIREMENTS BY FREERADIUS
For a secure FreeRADIUS service, you require TLS certificates for different purposes:
A TLS server certificate for encrypted connections to the server. Use a trusted certificate
authority (CA) to issue the certificate.
The server certificate requires the extended key usage (EKU) field set to TLS Web Server
Authentication.
Client certificates issued by the same CA for extended authentication protocol transport layer
security (EAP-TLS). EAP-TLS provides certificate-based authentication and is enabled by
default.
The client certificates require their EKU field set to TLS Web Client Authentication.
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WARNING
To secure connection, use your company’s CA or create your own CA to issue
certificates for FreeRADIUS. If you use a public CA, you allow it to authenticate
users and issue client certificates for EAP-TLS.
34.4. CREATING A SET OF CERTIFICATES ON A FREERADIUS SERVER
FOR TESTING PURPOSES
For testing purposes, the freeradius package installs scripts and configuration files in the
/etc/raddb/certs/ directory to create your own certificate authority (CA) and issue certificates.
IMPORTANT
If you use the default configuration, certificates generated by these scripts expire after
60 days and keys use an insecure password ("whatever"). However, you can customize
the CA, server, and client configuration.
After you perform the procedure, the following files, which you require later in this documentation, are
created:
/etc/raddb/certs/ca.pem: CA certificate
/etc/raddb/certs/server.key: Private key of the server certificate
/etc/raddb/certs/server.pem: Server certificate
/etc/raddb/certs/client.key: Private key of the client certificate
/etc/raddb/certs/client.pem: Client certificate
Prerequisites
You installed the freeradius package.
Procedure
1. Change into the /etc/raddb/certs/ directory:
# cd /etc/raddb/certs/
2. Optional: Customize the CA configuration in the /etc/raddb/certs/ca.cnf file:
...
[ req ]
default_bits = 2048
input_password = ca_password
output_password = ca_password
...
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[certificate_authority]
countryName = US
stateOrProvinceName = North Carolina
localityName = Raleigh
organizationName = Example Inc.
emailAddress = admin@example.org
commonName = "Example Certificate Authority"
...
3. Optional: Customize the server configuration in the /etc/raddb/certs/server.cnf file::
...
[ CA_default ]
default_days = 730
...
[ req ]
distinguished_name = server
default_bits = 2048
input_password = key_password
output_password = key_password
...
[server]
countryName = US
stateOrProvinceName = North Carolina
localityName = Raleigh
organizationName = Example Inc.
emailAddress = admin@example.org
commonName = "Example Server Certificate"
...
4. Optional: Customize the client configuration in the /etc/raddb/certs/client.cnf file::
...
[ CA_default ]
default_days = 365
...
[ req ]
distinguished_name = client
default_bits = 2048
input_password = password_on_private_key
output_password = password_on_private_key
...
[client]
countryName = US
stateOrProvinceName = North Carolina
localityName = Raleigh
organizationName = Example Inc.
emailAddress = user@example.org
commonName = user@example.org
...
5. Create the certificates:
# make all
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6. Change the group on the /etc/raddb/certs/server.pem file to radiusd:
# chgrp radiusd /etc/raddb/certs/server.pem
Additional resources
/etc/raddb/certs/README.md
34.5. CONFIGURING FREERADIUS TO AUTHENTICATE NETWORK
CLIENTS SECURELY BY USING EAP
FreeRADIUS supports different methods of the Extensible authentication protocol (EAP). However, for
a secure network, configure FreeRADIUS to support only the following secure EAP authentication
methods:
EAP-TLS (transport layer security) uses a secure TLS connection to authenticate clients by
using certificates. To use EAP-TLS, you need TLS client certificates for each network client and
a server certificate for the server. Note that the same certificate authority (CA) must have
issued the certificates. Always use your own CA to create certificates, because all client
certificates issued by the CA you use can authenticate to your FreeRADIUS server.
EAP-TTLS (tunneled transport layer security) uses a secure TLS connection as the outer
authentication protocol to set up the tunnel. The inner authentication then uses, for example,
the password authentication protocol (PAP) or challenge handshake authentication protocol
(CHAP). To use EAP-TTLS, you need a TLS server certificate.
EAP-PEAP (protected extensible authentication protocol) uses a secure TLS connection as the
outer authentication protocol to set up the tunnel. The authenticator authenticates the
certificate of the RADIUS server. Afterwards, the supplicant authenticates through the
encrypted tunnel by using Microsoft challenge handshake authentication protocol version 2
(MS-CHAPv2) or other methods.
NOTE
The default FreeRADIUS configuration files serve as documentation and describe all
parameters and directives. If you want to disable certain features, comment them out
instead of removing the corresponding parts in the configuration files. This enables you
to preserve the structure of the configuration files and the included documentation.
Prerequisites
You installed the freeradius package.
The configuration files in the /etc/raddb/ directory are unchanged and as provided by the
freeradius package.
The following files exist on the server:
TLS private key of the FreeRADIUS host: /etc/raddb/certs/server.key
TLS server certificate of the FreeRADIUS host: /etc/raddb/certs/server.pem
TLS CA certificate: /etc/raddb/certs/ca.pem
If you store the files in a different location or if they have different names, set the
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If you store the files in a different location or if they have different names, set the
private_key_file, certificate_file, and ca_file parameters in the /etc/raddb/mods-
available/eap file accordingly.
Procedure
1. If the /etc/raddb/certs/dh with Diffie-Hellman (DH) parameters does not exist, create one. For
example, to create a DH file with a 2048 bits prime, enter:
# openssl dhparam -out /etc/raddb/certs/dh 2048
For security reasons, do not use a DH file with less than a 2048 bits prime. Depending on the
number of bits, the creation of the file can take several minutes.
2. Set secure permissions on the TLS private key, server certificate, CA certificate, and the file
with DH parameters:
# chmod 640 /etc/raddb/certs/server.key /etc/raddb/certs/server.pem
/etc/raddb/certs/ca.pem /etc/raddb/certs/dh
# chown root:radiusd /etc/raddb/certs/server.key /etc/raddb/certs/server.pem
/etc/raddb/certs/ca.pem /etc/raddb/certs/dh
3. Edit the /etc/raddb/mods-available/eap file:
a. Set the password of the private key in the private_key_password parameter:
eap {
...
tls-config tls-common {
...
private_key_password = key_password
...
}
}
b. Depending on your environment, set the default_eap_type parameter in the eap directive
to your primary EAP type you use:
eap {
...
default_eap_type = ttls
...
}
For a secure environment, use only ttls, tls, or peap.
c. Comment out the md5 directives to disable the insecure EAP-MD5 authentication method:
eap {
...
# md5 {
# }
...
}
Note that, in the default configuration file, other insecure EAP authentication methods are
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327
Note that, in the default configuration file, other insecure EAP authentication methods are
commented out by default.
4. Edit the /etc/raddb/sites-available/default file, and comment out all authentication methods
other than eap:
authenticate {
...
# Auth-Type PAP {
# pap
# }
# Auth-Type CHAP {
# chap
# }
# Auth-Type MS-CHAP {
# mschap
# }
# mschap
# digest
...
}
This leaves only EAP enabled for the outer authentication and disables plain-text
authentication methods.
5. Edit the /etc/raddb/clients.conf file:
a. Set a secure password in the localhost and localhost_ipv6 client directives:
client localhost {
ipaddr = 127.0.0.1
...
secret = localhost_client_password
...
}
client localhost_ipv6 {
ipv6addr = ::1
secret = localhost_client_password
}
b. Add a client directive for the network authenticator:
client hostapd.example.org {
ipaddr = 192.0.2.2/32
secret = hostapd_client_password
}
c. Optional: If other hosts should also be able to access the FreeRADIUS service, add client
directives for them as well, for example:
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client <hostname_or_description> {
ipaddr = <IP_address_or_range>
secret = <client_password>
}
The ipaddr parameter accepts IPv4 and IPv6 addresses, and you can use the optional
classless inter-domain routing (CIDR) notation to specify ranges. However, you can set only
one value in this parameter. For example, to grant access to both an IPv4 and IPv6 address,
you must add two client directives.
Use a descriptive name for the client directive, such as a hostname or a word that describes
where the IP range is used.
6. If you want to use EAP-TTLS or EAP-PEAP, add the users to the /etc/raddb/users file:
example_user Cleartext-Password := "user_password"
For users who should use certificate-based authentication (EAP-TLS), do not add any entry.
7. Verify the configuration files:
# radiusd -XC
...
Configuration appears to be OK
8. Open the RADIUS ports in the firewalld service:
# firewall-cmd --permanent --add-service=radius
# firewall-cmd --reload
9. Enable and start the radiusd service:
# systemctl enable --now radiusd
Verification
Testing EAP-TTLS authentication against a FreeRADIUS server or authenticator
Testing EAP-TLS authentication against a FreeRADIUS server or authenticator
Troubleshooting
1. Stop the radiusd service:
# systemctl stop radiusd
2. Start the service in debug mode:
# radiusd -X
...
Ready to process requests
3. Perform authentication tests on the FreeRADIUS host, as referenced in the Verification
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329
3. Perform authentication tests on the FreeRADIUS host, as referenced in the Verification
section.
Next steps
Disable no longer required authentication methods and other features you do not use.
34.6. CONFIGURING HOSTAPD AS AN AUTHENTICATOR IN A WIRED
NETWORK
The host access point daemon (hostapd) service can act as an authenticator in a wired network to
provide 802.1X authentication. For this, the hostapd service requires a RADIUS server that
authenticates the clients.
The hostapd service provides an integrated RADIUS server. However, use the integrated RADIUS server
only for testing purposes. For production environments, use FreeRADIUS server, which supports
additional features, such as different authentication methods and access control.
IMPORTANT
The hostapd service does not interact with the traffic plane. The service acts only as an
authenticator. For example, use a script or service that uses the hostapd control
interface to allow or deny traffic based on the result of authentication events.
Prerequisites
You installed the hostapd package.
The FreeRADIUS server has been configured, and it is ready to authenticate clients.
Procedure
1. Create the /etc/hostapd/hostapd.conf file with the following content:
# General settings of hostapd
# ===========================
# Control interface settings
ctrl_interface=/var/run/hostapd
ctrl_interface_group=wheel
# Enable logging for all modules
logger_syslog=-1
logger_stdout=-1
# Log level
logger_syslog_level=2
logger_stdout_level=2
# Wired 802.1X authentication
# ===========================
# Driver interface type
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driver=wired
# Enable IEEE 802.1X authorization
ieee8021x=1
# Use port access entry (PAE) group address
# (01:80:c2:00:00:03) when sending EAPOL frames
use_pae_group_addr=1
# Network interface for authentication requests
interface=br0
# RADIUS client configuration
# ===========================
# Local IP address used as NAS-IP-Address
own_ip_addr=192.0.2.2
# Unique NAS-Identifier within scope of RADIUS server
nas_identifier=hostapd.example.org
# RADIUS authentication server
auth_server_addr=192.0.2.1
auth_server_port=1812
auth_server_shared_secret=hostapd_client_password
# RADIUS accounting server
acct_server_addr=192.0.2.1
acct_server_port=1813
acct_server_shared_secret=hostapd_client_password
For further details about the parameters used in this configuration, see their descriptions in the
/usr/share/doc/hostapd/hostapd.conf example configuration file.
2. Enable and start the hostapd service:
# systemctl enable --now hostapd
Verification
See:
Testing EAP-TTLS authentication against a FreeRADIUS server or authenticator
Testing EAP-TLS authentication against a FreeRADIUS server or authenticator
Troubleshooting
1. Stop the hostapd service:
# systemctl stop hostapd
2. Start the service in debug mode:
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331
# hostapd -d /etc/hostapd/hostapd.conf
3. Perform authentication tests on the FreeRADIUS host, as referenced in the Verification
section.
Additional resources
hostapd.conf(5) man page
/usr/share/doc/hostapd/hostapd.conf file
34.7. TESTING EAP-TTLS AUTHENTICATION AGAINST A FREERADIUS
SERVER OR AUTHENTICATOR
To test if authentication by using extensible authentication protocol (EAP) over tunneled transport layer
security (EAP-TTLS) works as expected, run this procedure:
After you set up the FreeRADIUS server
After you set up the hostapd service as an authenticator for 802.1X network authentication.
The output of the test utilities used in this procedure provide additional information about the EAP
communication and help you to debug problems.
Prerequisites
When you want to authenticate to:
A FreeRADIUS server:
The eapol_test utility, provided by the hostapd package, is installed.
The client, on which you run this procedure, has been authorized in the FreeRADIUS
server’s client databases.
An authenticator, the wpa_supplicant utility, provided by the same-named package, is
installed.
You stored the certificate authority (CA) certificate in the /etc/pki/tls/certs/ca.pem file.
Procedure
1. Create the /etc/wpa_supplicant/wpa_supplicant-TTLS.conf file with the following content:
ap_scan=0
network={
eap=TTLS
eapol_flags=0
key_mgmt=IEEE8021X
# Anonymous identity (sent in unencrypted phase 1)
# Can be any string
anonymous_identity="anonymous"
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# Inner authentication (sent in TLS-encrypted phase 2)
phase2="auth=PAP"
identity="example_user"
password="user_password"
# CA certificate to validate the RADIUS server's identity
ca_cert="/etc/pki/tls/certs/ca.pem"
}
2. To authenticate to:
A FreeRADIUS server, enter:
# eapol_test -c /etc/wpa_supplicant/wpa_supplicant-TTLS.conf -a 192.0.2.1 -s
<client_password>
...
EAP: Status notification: remote certificate verification (param=success)
...
CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
...
SUCCESS
The -a option defines the IP address of the FreeRADIUS server, and the -s option specifies
the password for the host on which you run the command in the FreeRADIUS server’s client
configuration.
An authenticator, enter:
# wpa_supplicant -c /etc/wpa_supplicant/wpa_supplicant-TTLS.conf -D wired -i
enp0s31f6
...
enp0s31f6: CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
...
The -i option specifies the network interface name on which wpa_supplicant sends out
extended authentication protocol over LAN (EAPOL) packets.
For more debugging information, pass the -d option to the command.
Additional resources
/usr/share/doc/wpa_supplicant/wpa_supplicant.conf file
34.8. TESTING EAP-TLS AUTHENTICATION AGAINST A FREERADIUS
SERVER OR AUTHENTICATOR
To test if authentication by using extensible authentication protocol (EAP) transport layer security
(EAP-TLS) works as expected, run this procedure:
After you set up the FreeRADIUS server
After you set up the hostapd service as an authenticator for 802.1X network authentication.
The output of the test utilities used in this procedure provide additional information about the EAP
communication and help you to debug problems.
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Prerequisites
When you want to authenticate to:
A FreeRADIUS server:
The eapol_test utility, provided by the hostapd package, is installed.
The client, on which you run this procedure, has been authorized in the FreeRADIUS
server’s client databases.
An authenticator, the wpa_supplicant utility, provided by the same-named package, is
installed.
You stored the certificate authority (CA) certificate in the /etc/pki/tls/certs/ca.pem file.
The CA that issued the client certificate is the same that issued the server certificate of the
FreeRADIUS server.
You stored the client certificate in the /etc/pki/tls/certs/client.pem file.
You stored the private key of the client in the /etc/pki/tls/private/client.key
Procedure
1. Create the /etc/wpa_supplicant/wpa_supplicant-TLS.conf file with the following content:
ap_scan=0
network={
eap=TLS
eapol_flags=0
key_mgmt=IEEE8021X
identity="user@example.org"
client_cert="/etc/pki/tls/certs/client.pem"
private_key="/etc/pki/tls/private/client.key"
private_key_passwd="password_on_private_key"
# CA certificate to validate the RADIUS server's identity
ca_cert="/etc/pki/tls/certs/ca.pem"
}
2. To authenticate to:
A FreeRADIUS server, enter:
# eapol_test -c /etc/wpa_supplicant/wpa_supplicant-TLS.conf -a 192.0.2.1 -s
<client_password>
...
EAP: Status notification: remote certificate verification (param=success)
...
CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
...
SUCCESS
The -a option defines the IP address of the FreeRADIUS server, and the -s option specifies
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The -a option defines the IP address of the FreeRADIUS server, and the -s option specifies
the password for the host on which you run the command in the FreeRADIUS server’s client
configuration.
An authenticator, enter:
# wpa_supplicant -c /etc/wpa_supplicant/wpa_supplicant-TLS.conf -D wired -i
enp0s31f6
...
enp0s31f6: CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully
...
The -i option specifies the network interface name on which wpa_supplicant sends out
extended authentication protocol over LAN (EAPOL) packets.
For more debugging information, pass the -d option to the command.
Additional resources
/usr/share/doc/wpa_supplicant/wpa_supplicant.conf file
34.9. BLOCKING AND ALLOWING TRAFFIC BASED ON HOSTAPD
AUTHENTICATION EVENTS
The hostapd service does not interact with the traffic plane. The service acts only as an authenticator.
However, you can write a script to allow and deny traffic based on the result of authentication events.
IMPORTANT
This procedure is not supported and is no enterprise-ready solution. It only demonstrates
how to block or allow traffic by evaluating events retrieved by hostapd_cli.
When the 802-1x-tr-mgmt systemd service starts, RHEL blocks all traffic on the listen port of hostapd
except extensible authentication protocol over LAN (EAPOL) packets and uses the hostapd_cli utility
to connect to the hostapd control interface. The /usr/local/bin/802-1x-tr-mgmt script then evaluates
events. Depending on the different events received by hostapd_cli, the script allows or blocks traffic
for MAC addresses. Note that, when the 802-1x-tr-mgmt service stops, all traffic is automatically
allowed again.
Perform this procedure on the hostapd server.
Prerequisites
The hostapd service has been configured, and the service is ready to authenticate clients.
Procedure
1. Create the /usr/local/bin/802-1x-tr-mgmt file with the following content:
#!/bin/sh
if [ "x$1" == "xblock_all" ]
then
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2. Create the /etc/systemd/system/802-1x-tr-mgmt@.service systemd service file with the
following content:
[Unit]
Description=Example 802.1x traffic management for hostapd
After=hostapd.service
After=sys-devices-virtual-net-%i.device
[Service]
Type=simple
ExecStartPre=-/bin/sh -c '/usr/sbin/tc qdisc del dev %i ingress > /dev/null 2>&1'
nft delete table bridge tr-mgmt-br0 2>/dev/null || true
nft -f - << EOF
table bridge tr-mgmt-br0 {
set allowed_macs {
type ether_addr
}
chain accesscontrol {
ether saddr @allowed_macs accept
ether daddr @allowed_macs accept
drop
}
chain forward {
type filter hook forward priority 0; policy accept;
meta ibrname "br0" jump accesscontrol
}
}
EOF
echo "802-1x-tr-mgmt Blocking all traffic through br0. Traffic for given host will be allowed
after 802.1x authentication"
elif [ "x$1" == "xallow_all" ]
then
nft delete table bridge tr-mgmt-br0
echo "802-1x-tr-mgmt Allowed all forwarding again"
fi
case ${2:-NOTANEVENT} in
AP-STA-CONNECTED | CTRL-EVENT-EAP-SUCCESS | CTRL-EVENT-EAP-
SUCCESS2)
nft add element bridge tr-mgmt-br0 allowed_macs { $3 }
echo "$1: Allowed traffic from $3"
;;
AP-STA-DISCONNECTED | CTRL-EVENT-EAP-FAILURE)
nft delete element bridge tr-mgmt-br0 allowed_macs { $3 }
echo "802-1x-tr-mgmt $1: Denied traffic from $3"
;;
esac
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ExecStartPre=-/bin/sh -c '/usr/sbin/tc qdisc del dev %i clsact > /dev/null 2>&1'
ExecStartPre=/usr/sbin/tc qdisc add dev %i clsact
ExecStartPre=/usr/sbin/tc filter add dev %i ingress pref 10000 protocol 0x888e matchall
action ok index 100
ExecStartPre=/usr/sbin/tc filter add dev %i ingress pref 10001 protocol all matchall action
drop index 101
ExecStart=/usr/sbin/hostapd_cli -i %i -a /usr/local/bin/802-1x-tr-mgmt
ExecStopPost=-/usr/sbin/tc qdisc del dev %i clsact
[Install]
WantedBy=multi-user.target
3. Reload systemd:
# systemctl daemon-reload
4. Enable and start the 802-1x-tr-mgmt service with the interface name hostapd is listening on:
# systemctl enable --now 802-1x-tr-mgmt@br0.service
Verification
Authenticate with a client to the network. See:
Testing EAP-TTLS authentication against a FreeRADIUS server or authenticator
Testing EAP-TLS authentication against a FreeRADIUS server or authenticator
Additional resources
systemd.service(5) man page
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CHAPTER 35. GETTING STARTED WITH MULTIPATH TCP
Transmission Control Protocol (TCP) ensures reliable delivery of the data through the internet and
automatically adjusts its bandwidth in response to network load. Multipath TCP (MPTCP) is an extension
to the original TCP protocol (single-path). MPTCP enables a transport connection to operate across
multiple paths simultaneously, and brings network connection redundancy to user endpoint devices.
35.1. UNDERSTANDING MPTCP
The Multipath TCP (MPTCP) protocol allows for simultaneous usage of multiple paths between
connection endpoints. The protocol design improves connection stability and also brings other benefits
compared to the single-path TCP.
NOTE
In MPTCP terminology, links are considered as paths.
The following are some of the advantages of using MPTCP:
It allows a connection to simultaneously use multiple network interfaces.
In case a connection is bound to a link speed, the usage of multiple links can increase the
connection throughput. Note, that in case of the connection is bound to a CPU, the usage of
multiple links causes the connection slowdown.
It increases the resilience to link failures.
For more details about MPTCP, review the Additional resources.
Additional resources
Understanding Multipath TCP: High availability for endpoints and the networking highway of the
future
RFC8684: TCP Extensions for Multipath Operation with Multiple Addresses
35.2. PREPARING RHEL TO ENABLE MPTCP SUPPORT
By default the MPTCP support is disabled in RHEL. Enable MPTCP so that applications that support
this feature can use it. Additionally, you have to configure user space applications to force use MPTCP
sockets if those applications have TCP sockets by default.
Prerequisites
The following packages are installed:
iperf3
mptcpd
systemtap
Procedure
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1. Enable MPTCP sockets in the kernel:
# echo "net.mptcp.enabled=1" > /etc/sysctl.d/90-enable-MPTCP.conf
# sysctl -p /etc/sysctl.d/90-enable-MPTCP.conf
2. Start the iperf3 server, and force it to create MPTCP sockets instead of TCP sockets:
# mptcpize run iperf3 -s
Server listening on 5201
3. Connect the client to the server, and force it to create MPTCP sockets instead of TCP sockets:
# mptcpize iperf3 -c 127.0.0.1 -t 3
4. After the connection is established, verify the ss output to see the subflow-specific status:
# ss -nti '( dport :5201 )'
State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
ESTAB 0 0 127.0.0.1:41842 127.0.0.1:5201
cubic wscale:7,7 rto:205 rtt:4.455/8.878 ato:40 mss:21888 pmtu:65535 rcvmss:536
advmss:65483 cwnd:10 bytes_sent:141 bytes_acked:142 bytes_received:4 segs_out:8
segs_in:7 data_segs_out:3 data_segs_in:3 send 393050505bps lastsnd:2813 lastrcv:2772
lastack:2772 pacing_rate 785946640bps delivery_rate 10944000000bps delivered:4
busy:41ms rcv_space:43690 rcv_ssthresh:43690 minrtt:0.008 tcp-ulp-mptcp flags:Mmec
token:0000(id:0)/2ff053ec(id:0) seq:3e2cbea12d7673d4 sfseq:3 ssnoff:ad3d00f4 maplen:2
5. Verify MPTCP counters:
# nstat MPTcp*
#kernel
MPTcpExtMPCapableSYNRX 2 0.0
MPTcpExtMPCapableSYNTX 2 0.0
MPTcpExtMPCapableSYNACKRX 2 0.0
MPTcpExtMPCapableACKRX 2 0.0
Additional resources
tcp(7) man page
mptcpize(8) man page
35.3. USING IPROUTE2 TO TEMPORARILY CONFIGURE AND ENABLE
MULTIPLE PATHS FOR MPTCP APPLICATIONS
Each MPTCP connection uses a single subflow similar to plain TCP. To get the MPTCP benefits, specify
a higher limit for maximum number of subflows for each MPTCP connection. Then configure additional
endpoints to create those subflows.
IMPORTANT
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IMPORTANT
The configuration in this procedure will not persist after rebooting your machine.
Note that MPTCP does not yet support mixed IPv6 and IPv4 endpoints for the same socket. Use
endpoints belonging to the same address family.
Prerequisites
The mptcpd package is installed
The iperf3 package is installed
Server network interface settings:
enp4s0: 192.0.2.1/24
enp1s0: 198.51.100.1/24
Client network interface settings:
enp4s0f0: 192.0.2.2/24
enp4s0f1: 198.51.100.2/24
Procedure
1. Configure the client to accept up to 1 additional remote address, as provided by the server:
# ip mptcp limits set add_addr_accepted 1
2. Add IP address 198.51.100.1 as a new MPTCP endpoint on the server:
# ip mptcp endpoint add 198.51.100.1 dev enp1s0 signal
The signal option ensures that the ADD_ADDR packet is sent after the three-way-handshake.
3. Start the iperf3 server, and force it to create MPTCP sockets instead of TCP sockets:
# mptcpize run iperf3 -s
Server listening on 5201
4. Connect the client to the server, and force it to create MPTCP sockets instead of TCP sockets:
# mptcpize iperf3 -c 192.0.2.1 -t 3
Verification
1. Verify the connection is established:
# ss -nti '( sport :5201 )'
2. Verify the connection and IP address limit:
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# ip mptcp limit show
3. Verify the newly added endpoint:
# ip mptcp endpoint show
4. Verify MPTCP counters by using the nstat MPTcp* command on a server:
# nstat MPTcp*
#kernel
MPTcpExtMPCapableSYNRX 2 0.0
MPTcpExtMPCapableACKRX 2 0.0
MPTcpExtMPJoinSynRx 2 0.0
MPTcpExtMPJoinAckRx 2 0.0
MPTcpExtEchoAdd 2 0.0
Additional resources
ip-mptcp(8) man page
mptcpize(8) man page
35.4. PERMANENTLY CONFIGURING MULTIPLE PATHS FOR MPTCP
APPLICATIONS
You can configure MultiPath TCP (MPTCP) using the nmcli command to permanently establish
multiple subflows between a source and destination system. The subflows can use different resources,
different routes to the destination, and even different networks. Such as Ethernet, cellular, wifi, and so
on. As a result, you achieve combined connections, which increase network resilience and throughput.
The server uses the following network interfaces in our example:
enp4s0: 192.0.2.1/24
enp1s0: 198.51.100.1/24
enp7s0: 192.0.2.3/24
The client uses the following network interfaces in our example:
enp4s0f0: 192.0.2.2/24
enp4s0f1: 198.51.100.2/24
enp6s0: 192.0.2.5/24
Prerequisites
You configured the default gateway on the relevant interfaces.
Procedure
1. Enable MPTCP sockets in the kernel:
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# echo "net.mptcp.enabled=1" > /etc/sysctl.d/90-enable-MPTCP.conf
# sysctl -p /etc/sysctl.d/90-enable-MPTCP.conf
2. Optional: The RHEL kernel default for subflow limit is 2. If you require more:
a. Create the /etc/systemd/system/set_mptcp_limit.service file with the following content:
[Unit]
Description=Set MPTCP subflow limit to 3
After=network.target
[Service]
ExecStart=ip mptcp limits set subflows 3
Type=oneshot
[Install]
WantedBy=multi-user.target
The oneshot unit executes the ip mptcp limits set subflows 3 command after your
network (network.target) is operational during every boot process.
The ip mptcp limits set subflows 3 command sets the maximum number of additional
subflows for each connection, so 4 in total. It is possible to add maximally 3 additional
subflows.
b. Enable the set_mptcp_limit service:
# systemctl enable --now set_mptcp_limit
3. Enable MPTCP on all connection profiles that you want to use for connection aggregation:
# nmcli connection modify <profile_name> connection.mptcp-flags
signal,subflow,also-without-default-route
The connection.mptcp-flags parameter configures MPTCP endpoints and the IP address
flags. If MPTCP is enabled in a NetworkManager connection profile, the setting will configure
the IP addresses of the relevant network interface as MPTCP endpoints.
By default, NetworkManager does not add MPTCP flags to IP addresses if there is no default
gateway. If you want to bypass that check, you need to use also the also-without-default-route
flag.
Verification
1. Verify that you enabled the MPTCP kernel parameter:
# sysctl net.mptcp.enabled
net.mptcp.enabled = 1
2. Verify that you set the subflow limit correctly, in case the default was not enough:
# ip mptcp limit show
add_addr_accepted 2 subflows 3
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3. Verify that you configured the per-address MPTCP setting correctly:
# ip mptcp endpoint show
192.0.2.1 id 1 subflow dev enp4s0
198.51.100.1 id 2 subflow dev enp1s0
192.0.2.3 id 3 subflow dev enp7s0
192.0.2.4 id 4 subflow dev enp3s0
...
Additional resources
nm-settings-nmcli(5)
ip-mptcp(8)
Section 35.1, “Understanding MPTCP”
Understanding Multipath TCP: High availability for endpoints and the networking highway of the
future
RFC8684: TCP Extensions for Multipath Operation with Multiple Addresses
Using Multipath TCP to better survive outages and increase bandwidth
35.5. MONITORING MPTCP SUB-FLOWS
The life cycle of a multipath TCP (MPTCP) socket can be complex: The main MPTCP socket is created,
the MPTCP path is validated, one or more sub-flows are created and eventually removed. Finally, the
MPTCP socket is terminated.
The MPTCP protocol allows monitoring MPTCP-specific events related to socket and sub-flow creation
and deletion, using the ip utility provided by the iproute package. This utility uses the netlink interface
to monitor MPTCP events.
This procedure demonstrates how to monitor MPTCP events. For that, it simulates a MPTCP server
application, and a client connects to this service. The involved clients in this example use the following
interfaces and IP addresses:
Server: 192.0.2.1
Client (Ethernet connection): 192.0.2.2
Client (WiFi connection): 192.0.2.3
To simplify this example, all interfaces are within the same subnet. This is not a requirement. However, it
is important that routing has been configured correctly, and the client can reach the server via both
interfaces.
Prerequisites
A RHEL client with two network interfaces, such as a laptop with Ethernet and WiFi
The client can connect to the server via both interfaces
A RHEL server
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Both the client and the server run RHEL 9.0 or later
You installed the mptcpd package on both the client and the server
Procedure
1. Set the per connection additional subflow limits to 1 on both client and server:
# ip mptcp limits set add_addr_accepted 0 subflows 1
2. On the server, to simulate a MPTCP server application, start netcat (nc) in listen mode with
enforced MPTCP sockets instead of TCP sockets:
# mptcpize run nc -l -k -p 12345
The -k option causes that nc does not close the listener after the first accepted connection.
This is required to demonstrate the monitoring of sub-flows.
3. On the client:
a. Identify the interface with the lowest metric:
# ip -4 route
192.0.2.0/24 dev enp1s0 proto kernel scope link src 192.0.2.2 metric 100
192.0.2.0/24 dev wlp1s0 proto kernel scope link src 192.0.2.3 metric 600
The enp1s0 interface has a lower metric than wlp1s0. Therefore, RHEL uses enp1s0 by
default.
b. On the first terminal, start the monitoring:
# ip mptcp monitor
c. On the second terminal, start a MPTCP connection to the server:
# mptcpize run nc 192.0.2.1 12345
RHEL uses the enp1s0 interface and its associated IP address as a source for this
connection.
On the monitoring terminal, the ip mptcp monitor command now logs:
[ CREATED] token=63c070d2 remid=0 locid=0 saddr4=192.0.2.2 daddr4=192.0.2.1
sport=36444 dport=12345
The token identifies the MPTCP socket as an unique ID, and later it enables you to correlate
MPTCP events on the same socket.
d. On the terminal with the running nc connection to the server, press Enter. This first data
packet fully establishes the connection. Note that, as long as no data has been sent, the
connection is not established.
On the monitoring terminal, ip mptcp monitor now logs:
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[ ESTABLISHED] token=63c070d2 remid=0 locid=0 saddr4=192.0.2.2
daddr4=192.0.2.1 sport=36444 dport=12345
e. Optional: Display the connections to port 12345 on the server:
# ss -taunp | grep ":12345"
tcp ESTAB 0 0 192.0.2.2:36444 192.0.2.1:12345
At this point, only one connection to the server has been established.
f. On a third terminal, create another endpoint:
# ip mptcp endpoint add dev wlp1s0 192.0.2.3 subflow
This command sets the name and IP address of the WiFi interface of the client in this
command.
On the monitoring terminal, ip mptcp monitor now logs:
[SF_ESTABLISHED] token=63c070d2 remid=0 locid=2 saddr4=192.0.2.3
daddr4=192.0.2.1 sport=53345 dport=12345 backup=0 ifindex=3
The locid field displays the local address ID of the new sub-flow and identifies this sub-flow
even if the connection uses network address translation (NAT). The saddr4 field matches
the endpoint’s IP address from the ip mptcp endpoint add command.
g. Optional: Display the connections to port 12345 on the server:
# ss -taunp | grep ":12345"
tcp ESTAB 0 0 192.0.2.2:36444 192.0.2.1:12345
tcp ESTAB 0 0 192.0.2.3%wlp1s0:53345 192.0.2.1:12345
The command now displays two connections:
The connection with source address 192.0.2.2 corresponds to the first MPTCP sub-
flow that you established previously.
The connection from the sub-flow over the wlp1s0 interface with source address
192.0.2.3.
h. On the third terminal, delete the endpoint:
# ip mptcp endpoint delete id 2
Use the ID from the locid field from the ip mptcp monitor output, or retrieve the endpoint
ID using the ip mptcp endpoint show command.
On the monitoring terminal, ip mptcp monitor now logs:
[ SF_CLOSED] token=63c070d2 remid=0 locid=2 saddr4=192.0.2.3 daddr4=192.0.2.1
sport=53345 dport=12345 backup=0 ifindex=3
i. On the first terminal with the nc client, press Ctrl+C to terminate the session.
On the monitoring terminal, ip mptcp monitor now logs:
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345
[ CLOSED] token=63c070d2
Additional resources
ip-mptcp(1) man page
How NetworkManager manages multiple default gateways
35.6. DISABLING MULTIPATH TCP IN THE KERNEL
You can explicitly disable the MPTCP option in the kernel.
Procedure
Disable the mptcp.enabled option.
# echo "net.mptcp.enabled=0" > /etc/sysctl.d/90-enable-MPTCP.conf
# sysctl -p /etc/sysctl.d/90-enable-MPTCP.conf
Verification
Verify whether the mptcp.enabled is disabled in the kernel.
# sysctl -a | grep mptcp.enabled
net.mptcp.enabled = 0
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CHAPTER 36. MANAGING THE MPTCPD SERVICE
This section describes the basic management of the mptcpd service. The mptcpd package provides
the mptcpize tool, which switches on the mptcp protocol in the TCP environment.
36.1. CONFIGURING MPTCPD
The mptcpd service is a component of the mptcp protocol which provides an instrument to configure
mptcp endpoints. The mptcpd service creates a subflow endpoint for each address by default. The
endpoint list is updated dynamically according to IP addresses modification on the running host. The
mptcpd service creates the list of endpoints automatically. It enables multiple paths as an alternative to
using the ip utility.
Prerequisites
The mptcpd package installed
Procedure
1. Enable mptcp.enabled option in the kernel with the following command:
# echo "net.mptcp.enabled=1" > /etc/sysctl.d/90-enable-MPTCP.conf
# sysctl -p /etc/sysctl.d/90-enable-MPTCP.conf
2. Start the mptcpd service:
# systemctl start mptcp.service
3. Verify endpoint creation:
# ip mptcp endpoint
4. To stop the mptcpd service, use the following command:
# systemctl stop mptcp.service
5. To configure mptcpd service manually, modify the /etc/mptcpd/mptcpd.conf configuration file.
Note, that the endpoint, which mptcpd service creates, lasts till the host shutdown.
Additional resources
mptcpd(8) man page.
36.2. MANAGING APPLICATIONS WITH MPTCPIZE TOOL
Using the mptcpize tool manage applications and services.
The instruction below shows how to use the mptcpize tool to manage applications in the TCP
environment.
Assuming, you need to run the iperf3 utility with the enabled MPTCP socket. You can achieve this goal
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347
Assuming, you need to run the iperf3 utility with the enabled MPTCP socket. You can achieve this goal
by following the procedure below.
Prerequisites
The mptcpd package is installed
The iperf3 package is installed
Procedure
Start iperf3 utility with MPTCP sockets enabled:
# mptcpize run iperf3 -s &
36.3. ENABLING MPTCP SOCKETS FOR A SERVICES USING THE
MPTCPIZE UTILITY
The following set of commands instruct you how to manage services using the mptcpize tool. You can
enable or disable the mptcp socket for a service.
Assuming, you need to manage mptcp socket for the nginx service. You can achieve this goal by
following the procedure below.
Prerequisites
The mptcpd package is installed
The nginx package is installed
Procedure
1. Enable MPTCP sockets for a service:
# mptcpize enable nginx
2. Disable the MPTCP sockets for a service:
# mptcpize disable nginx
3. Restart the service to make the changes to take effect:
# systemctl restart nginx
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CHAPTER 37. NETWORKMANAGER CONNECTION PROFILES
IN KEYFILE FORMAT
By default, NetworkManager in Red Hat Enterprise Linux 9 and later stores connection profiles in keyfile
format. Unlike the deprecated ifcfg format, the keyfile format supports all connection settings that
NetworkManager provides.
37.1. THE KEYFILE FORMAT OF NETWORKMANAGER PROFILES
The keyfile format is similar to the INI format. For example, the following is an Ethernet connection
profile in keyfile format:
[connection]
id=example_connection
uuid=82c6272d-1ff7-4d56-9c7c-0eb27c300029
type=ethernet
autoconnect=true
[ipv4]
method=auto
[ipv6]
method=auto
[ethernet]
mac-address=00:53:00:8f:fa:66
WARNING
Typos or incorrect placements of parameters can lead to unexpected behavior.
Therefore, do not manually edit or create NetworkManager profiles.
Use the nmcli utility, the network RHEL system role, or the nmstate API to
manage NetworkManager connections. For example, you can use the nmcli utility in
offline mode to create connection profiles.
Each section corresponds to a NetworkManager setting name as described in the nm-settings(5) and
nm-settings-keyfile(5) man pages. Each key-value-pair in a section is one of the properties listed in the
settings specification of the man page.
Most variables in NetworkManager keyfiles have a one-to-one mapping. This means that a
NetworkManager property is stored in the keyfile as a variable of the same name and in the same
format. However, there are exceptions, mainly to make the keyfile syntax easier to read. For a list of
these exceptions, see the nm-settings-keyfile(5) man page.
IMPORTANT
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349
IMPORTANT
For security reasons, because connection profiles can contain sensitive information, such
as private keys and passphrases, NetworkManager uses only configuration files owned by
the root user and that are only readable and writable by root.
Depending on the purpose of the connection profile, save it in one of the following directories:
/etc/NetworkManager/system-connections/: The location of persistent profiles. If you modify
a persistent profile by using the NetworkManager API, NetworkManager writes and overwrites
files in this directory.
/run/NetworkManager/system-connections/: For temporary profiles that are automatically
removed when you reboot the system.
/usr/lib/NetworkManager/system-connections/: For pre-deployed immutable profiles. When
you edit such a profile using the NetworkManager API, NetworkManager copies this profile to
either the persistent or temporary storage.
NetworkManager does not automatically reload profiles from disk. When you create or update a
connection profile in keyfile format, use the nmcli connection reload command to inform
NetworkManager about the changes.
37.2. USING NMCLI TO CREATE KEYFILE CONNECTION PROFILES IN
OFFLINE MODE
Use NetworkManager utilities, such as nmcli, the network RHEL system role, or the nmstate API to
manage NetworkManager connections, to create and update configuration files. However, you can also
create various connection profiles in the keyfile format in offline mode using the nmcli --offline
connection add command.
The offline mode ensures that nmcli operates without the NetworkManager service to produce keyfile
connection profiles through standard output. This feature can be useful if:
You want to create your connection profiles that need to be pre-deployed somewhere. For
example in a container image, or as an RPM package.
You want to create your connection profiles in an environment where the NetworkManager
service is not available. For example when you want to use the chroot utility. Alternatively, when
you want to create or modify the network configuration of the RHEL system to be installed
through the Kickstart %post script.
You can create the following connection profile types:
static Ethernet connection
dynamic Ethernet connection
network bond
network bridge
VLAN or any kind of supported connections
Procedure
1. Create a new connection profile in the keyfile format. For example, for a connection profile of an
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1. Create a new connection profile in the keyfile format. For example, for a connection profile of an
Ethernet device that does not use DHCP, run a similar nmcli command:
# nmcli --offline connection add type ethernet con-name Example-Connection
ipv4.addresses 192.0.2.1/24 ipv4.dns 192.0.2.200 ipv4.method manual >
/etc/NetworkManager/system-connections/output.nmconnection
NOTE
The connection name you specified with the con-name key is saved into the id
variable of the generated profile. When you use the nmcli command to manage
this connection later, specify the connection as follows:
When the id variable is not omitted, use the connection name, for example
Example-Connection.
When the id variable is omitted, use the file name without the
.nmconnection suffix, for example output.
2. Set permissions to the configuration file so that only the root user can read and update it:
# chmod 600 /etc/NetworkManager/system-connections/output.nmconnection
# chown root:root /etc/NetworkManager/system-connections/output.nmconnection
3. Start the NetworkManager service:
# systemctl start NetworkManager.service
4. If you set the autoconnect variable in the profile to false, activate the connection:
# nmcli connection up Example-Connection
Verification
1. Verify that the NetworkManager service is running:
# systemctl status NetworkManager.service
● NetworkManager.service - Network Manager
Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service; enabled; vendor preset:
enabled)
Active: active (running) since Wed 2022-08-03 13:08:32 CEST; 1min 40s ago
...
2. Verify that NetworkManager can read the profile from the configuration file:
# nmcli -f TYPE,FILENAME,NAME connection
TYPE FILENAME NAME
ethernet /etc/NetworkManager/system-connections/output.nmconnection Example-
Connection
ethernet /etc/sysconfig/network-scripts/ifcfg-enp1s0 enp1s0
...
If the output does not show the newly created connection, verify that the keyfile permissions
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If the output does not show the newly created connection, verify that the keyfile permissions
and the syntax you used are correct.
3. Display the connection profile:
# nmcli connection show Example-Connection
connection.id: Example-Connection
connection.uuid: 232290ce-5225-422a-9228-cb83b22056b4
connection.stable-id: --
connection.type: 802-3-ethernet
connection.interface-name: --
connection.autoconnect: yes
...
Additional resources
nmcli(1)
nm-settings-keyfile(5)
The keyfile format of NetworkManager profiles
Configuring an Ethernet connection by using nmcli
Configuring VLAN tagging by using nmcli
Configuring a network bridge by using nmcli
Configuring a network bond by using nmcli
37.3. MANUALLY CREATING A NETWORKMANAGER PROFILE IN
KEYFILE FORMAT
You can manually create a NetworkManager connection profile in keyfile format.
NOTE
Manually creating or updating the configuration files can result in an unexpected or non-
functional network configuration. As an alternative, you can use nmcli in offline mode.
See Using nmcli to create keyfile connection profiles in offline mode
Procedure
1. If you create a profile for a hardware interface, such as Ethernet, display the MAC address of this
interface:
# ip address show enp1s0
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP
group default qlen 1000
link/ether 00:53:00:8f:fa:66 brd ff:ff:ff:ff:ff:ff
2. Create a connection profile. For example, for a connection profile of an Ethernet device that
uses DHCP, create the /etc/NetworkManager/system-connections/example.nmconnection
file with the following content:
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[connection]
id=example_connection
type=ethernet
autoconnect=true
[ipv4]
method=auto
[ipv6]
method=auto
[ethernet]
mac-address=00:53:00:8f:fa:66
NOTE
You can use any file name with a .nmconnection suffix. However, when you later
use nmcli commands to manage the connection, you must use the connection
name set in the id variable when you refer to this connection. When you omit the
id variable, use the file name without the .nmconnection to refer to this
connection.
3. Set permissions on the configuration file so that only the root user can read and update it:
# chown root:root /etc/NetworkManager/system-connections/example.nmconnection
# chmod 600 /etc/NetworkManager/system-connections/example.nmconnection
4. Reload the connection profiles:
# nmcli connection reload
5. Verify that NetworkManager read the profile from the configuration file:
# nmcli -f NAME,UUID,FILENAME connection
NAME UUID FILENAME
example-connection 86da2486-068d-4d05-9ac7-957ec118afba
/etc/NetworkManager/system-connections/example.nmconnection
...
If the command does not show the newly added connection, verify that the file permissions and
the syntax you used in the file are correct.
6. If you set the autoconnect variable in the profile to false, activate the connection:
# nmcli connection up example_connection
Verification
1. Display the connection profile:
# nmcli connection show example_connection
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Additional resources
nm-settings-keyfile (5)
37.4. THE DIFFERENCES IN INTERFACE RENAMING WITH PROFILES
IN IFCFG AND KEYFILE FORMAT
You can define custom network interface names, such as provider or lan to make interface names more
descriptive. In this case, the udev service renames the interfaces. The renaming process works
differently depending on whether you use connection profiles in ifcfg or keyfile format.
The interface renaming process when using a profile in ifcfg format
1. The /usr/lib/udev/rules.d/60-net.rules udev rule calls the /lib/udev/rename_device helper
utility.
2. The helper utility searches for the HWADDR parameter in /etc/sysconfig/network-
scripts/ifcfg-* files.
3. If the value set in the variable matches the MAC address of an interface, the helper utility
renames the interface to the name set in the DEVICE parameter of the file.
The interface renaming process when using a profile in keyfile format
1. Create a systemd link file or a udev rule to rename an interface.
2. Use the custom interface name in the interface-name property of a NetworkManager
connection profile.
Additional resources
How the udev device manager renames network interfaces
Configuring user-defined network interface names by using udev rules
Configuring user-defined network interface names by using systemd link files
37.5. MIGRATING NETWORKMANAGER PROFILES FROM IFCFG TO
KEYFILE FORMAT
If you still use connection profiles in the deprecated ifcfg format, you can convert them to the keyfile
format.
NOTE
If an ifcfg file contains the NM_CONTROLLED=no setting, NetworkManager does not
control this profile and, consequently the migration process ignores it.
Prerequisites
You have connection profiles in ifcfg format in the /etc/sysconfig/network-scripts/ directory.
If the connection profiles contain a DEVICE variable that is set to a custom device name, such
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If the connection profiles contain a DEVICE variable that is set to a custom device name, such
as provider or lan, you created a systemd link file or a udev rule for each of the custom device
names.
Procedure
Migrate the connection profiles:
# nmcli connection migrate
Connection 'enp1s0' (43ed18ab-f0c4-4934-af3d-2b3333948e45) successfully migrated.
Connection 'enp2s0' (883333e8-1b87-4947-8ceb-1f8812a80a9b) successfully migrated.
...
Verification
Optionally, you can verify that you successfully migrated all your connection profiles:
# nmcli -f TYPE,FILENAME,NAME connection
TYPE FILENAME NAME
ethernet /etc/NetworkManager/system-connections/enp1s0.nmconnection enp1s0
ethernet /etc/NetworkManager/system-connections/enp2s0.nmconnection enp2s0
...
Additional resources
nm-settings-keyfile(5)
nm-settings-ifcfg-rh(5)
How the udev device manager renames network interfaces
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CHAPTER 38. SYSTEMD NETWORK TARGETS AND SERVICES
NetworkManager configures the network during the system boot process. However, when booting with
a remote root (/), such as if the root directory is stored on an iSCSI device, the network settings are
applied in the initial RAM disk (initrd) before RHEL is started. For example, if the network configuration
is specified on the kernel command line using rd.neednet=1 or a configuration is specified to mount
remote file systems, then the network settings are applied on initrd.
RHEL uses the network and network-online targets and the NetworkManager-wait-online service
while applying network settings. Also, you can configure systemd services to start after the network is
fully available if these services cannot dynamically reload.
38.1. DIFFERENCES BETWEEN THE NETWORK AND NETWORK-
ONLINE SYSTEMD TARGET
Systemd maintains the network and network-online target units. The special units such as
NetworkManager-wait-online.service, have WantedBy=network-online.target and Before=network-
online.target parameters. If enabled, these units get started with network-online.target and delay the
target to be reached until some form of network connectivity is established. They delay the network-
online target until the network is connected.
The network-online target starts a service, which adds substantial delays to further execution. Systemd
automatically adds dependencies with Wants and After parameters for this target unit to all the System
V (SysV) init script service units with a Linux Standard Base (LSB) header referring to the $network
facility. The LSB header is metadata for init scripts. You can use it to specify dependencies. This is
similar to the systemd target.
The network target does not significantly delay the execution of the boot process. Reaching the
network target means that the service that is responsible for setting up the network has started.
However, it does not mean that a network device was configured. This target is important during the
shutdown of the system. For example, if you have a service that was ordered after the network target
during bootup, then this dependency is reversed during the shutdown. The network does not get
disconnected until your service has been stopped. All mount units for remote network file systems
automatically start the network-online target unit and order themselves after it.
NOTE
The network-online target unit is only useful during the system starts. After the system
has completed booting up, this target does not track the online state of the network.
Therefore, you cannot use network-online to monitor the network connection. This
target provides a one-time system startup concept.
38.2. OVERVIEW OF NETWORKMANAGER-WAIT-ONLINE
The NetworkManager-wait-online service waits with a timeout for the network to be configured. This
network configuration involves plugging-in an Ethernet device, scanning for a Wi-Fi device, and so forth.
NetworkManager automatically activates suitable profiles that are configured to start automatically. The
failure of the automatic activation process due to a DHCP timeout or similar event might keep
NetworkManager busy for an extended period of time. Depending on the configuration,
NetworkManager retries activating the same profile or a different profile.
When the startup completes, either all profiles are in a disconnected state or are successfully activated.
You can configure profiles to auto-connect. The following are a few examples of parameters that set
timeouts or define when the connection is considered active:
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connection.wait-device-timeout - sets the timeout for the driver to detect the device
ipv4.may-fail and ipv6.may-fail - sets activation with one IP address family ready, or whether a
particular address family must have completed configuration.
ipv4.gateway-ping-timeout - delays activation.
Additional resources
nm-settings(5) man page
38.3. CONFIGURING A SYSTEMD SERVICE TO START AFTER THE
NETWORK HAS BEEN STARTED
Red Hat Enterprise Linux installs systemd service files in the /usr/lib/systemd/system/ directory. This
procedure creates a drop-in snippet for a service file in /etc/systemd/system/service_name.service.d/
that is used together with the service file in /usr/lib/systemd/system/ to start a particular service after
the network is online. It has a higher priority if settings in the drop-in snippet overlap with the ones in the
service file in /usr/lib/systemd/system/.
Procedure
1. To open the service file in the editor, enter:
# systemctl edit service_name
2. Enter the following, and save the changes:
[Unit]
After=network-online.target
3. Reload the systemd service.
# systemctl daemon-reload
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CHAPTER 39. INTRODUCTION TO NMSTATE
Nmstate is a declarative network manager API. The nmstate package provides the libnmstate Python
library and a command-line utility, nmstatectl, to manage NetworkManager on RHEL. When you use
Nmstate, you describe the expected networking state using YAML or JSON-formatted instructions.
Nmstate has many benefits. For example, it:
Provides a stable and extensible interface to manage RHEL network capabilities
Supports atomic and transactional operations at the host and cluster level
Supports partial editing of most properties and preserves existing settings that are not specified
in the instructions
Provides plug-in support to enable administrators to use their own plug-ins
39.1. USING THE LIBNMSTATE LIBRARY IN A PYTHON APPLICATION
The libnmstate Python library enables developers to use Nmstate in their own application
To use the library, import it in your source code:
import libnmstate
Note that you must install the nmstate and python3-libnmstate packages to use this library.
Example 39.1. Querying the network state using the libnmstate library
The following Python code imports the libnmstate library and displays the available network
interfaces and their state:
39.2. UPDATING THE CURRENT NETWORK CONFIGURATION USING
NMSTATECTL
You can use the nmstatectl utility to store the current network configuration of one or all interfaces in a
file. You can then use this file to:
Modify the configuration and apply it to the same system.
Copy the file to a different host and configure the host with the same or modified settings.
For example, you can export the settings of the enp1s0 interface to a file, modify the configuration, and
import json
import libnmstate
from libnmstate.schema import Interface
net_state = libnmstate.show()
for iface_state in net_state[Interface.KEY]:
print(iface_state[Interface.NAME] + ": "
+ iface_state[Interface.STATE])
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For example, you can export the settings of the enp1s0 interface to a file, modify the configuration, and
apply the settings to the host.
Prerequisites
The nmstate package is installed.
Procedure
1. Export the settings of the enp1s0 interface to the ~/network-config.yml file:
# nmstatectl show enp1s0 > ~/network-config.yml
This command stores the configuration of enp1s0 in YAML format. To store the output in
JSON format, pass the --json option to the command.
If you do not specify an interface name, nmstatectl exports the configuration of all interfaces.
2. Modify the ~/network-config.yml file using a text editor to update the configuration.
3. Apply the settings from the ~/network-config.yml file:
# nmstatectl apply ~/network-config.yml
If you exported the settings in JSON format, pass the --json option to the command.
39.3. THE NMSTATE SYSTEMD SERVICE
You can automatically apply new network settings when the Red Hat Enterprise Linux system boots by
configuring the nmstate systemd service.
With the nmstate package installed, you can store *.yml files with Nmstate instructions in the
/etc/nmstate/ directory. The nmstate service then automatically applies the files on the next reboot or
when you manually restart the service. After Nmstate successfully applies a file, it renames the file’s .yml
suffix to .applied to prevent the service from processing the same file again.
The nmstate service is a oneshot systemd service. Consequently, systemd executes it only when the
system boots and when you manually restart the service.
NOTE
By default, the nmstate service is disabled. Use the systemctl enable nmstate
command to enable it. Afterwards, systemd executes this service each time when the
system starts.
39.4. NETWORK STATES FOR THE NETWORK RHEL SYSTEM ROLE
The network RHEL system role supports state configurations in playbooks to configure the devices. For
this, use the network_state variable followed by the state configurations.
Benefits of using the network_state variable in a playbook:
Using the declarative method with the state configurations, you can configure interfaces, and
the NetworkManager creates a profile for these interfaces in the background.
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With the network_state variable, you can specify the options that you require to change, and all
the other options will remain the same as they are. However, with the network_connections
variable, you must specify all settings to change the network connection profile.
For example, to create an Ethernet connection with dynamic IP address settings, use the following vars
block in your playbook:
Playbook with state configurations Regular playbook
For example, to only change the connection status of dynamic IP address settings that you created as
above, use the following vars block in your playbook:
Playbook with state configurations Regular playbook
Additional resources
/usr/share/ansible/roles/rhel-system-roles.network/README.md file
vars:
network_state:
interfaces:
- name: enp7s0
type: ethernet
state: up
ipv4:
enabled: true
auto-dns: true
auto-gateway: true
auto-routes: true
dhcp: true
ipv6:
enabled: true
auto-dns: true
auto-gateway: true
auto-routes: true
autoconf: true
dhcp: true
vars:
network_connections:
- name: enp7s0
interface_name: enp7s0
type: ethernet
autoconnect: yes
ip:
dhcp4: yes
auto6: yes
state: up
vars:
network_state:
interfaces:
- name: enp7s0
type: ethernet
state: down
vars:
network_connections:
- name: enp7s0
interface_name: enp7s0
type: ethernet
autoconnect: yes
ip:
dhcp4: yes
auto6: yes
state: down
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/usr/share/doc/rhel-system-roles/network/ directory
39.5. ADDITIONAL RESOURCES
/usr/share/doc/nmstate/README.md
/usr/share/doc/nmstate/examples/
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CHAPTER 40. CAPTURING NETWORK PACKETS
To debug network issues and communications, you can capture network packets. The following sections
provide instructions and additional information about capturing network packets.
40.1. USING XDPDUMP TO CAPTURE NETWORK PACKETS INCLUDING
PACKETS DROPPED BY XDP PROGRAMS
The xdpdump utility captures network packets. Unlike the tcpdump utility, xdpdump uses an extended
Berkeley Packet Filter(eBPF) program for this task. This enables xdpdump to also capture packets
dropped by Express Data Path (XDP) programs. User-space utilities, such as tcpdump, are not able to
capture these dropped packages, as well as original packets modified by an XDP program.
You can use xdpdump to debug XDP programs that are already attached to an interface. Therefore, the
utility can capture packets before an XDP program is started and after it has finished. In the latter case,
xdpdump also captures the XDP action. By default, xdpdump captures incoming packets at the entry
of the XDP program.
IMPORTANT
On other architectures than AMD and Intel 64-bit, the xdpdump utility is provided as a
Technology Preview only. Technology Preview features are not supported with Red Hat
production Service Level Agreements (SLAs), might not be functionally complete, and
Red Hat does not recommend using them for production. These previews provide early
access to upcoming product features, enabling customers to test functionality and
provide feedback during the development process.
See Technology Preview Features Support Scope on the Red Hat Customer Portal for
information about the support scope for Technology Preview features.
Note that xdpdump has no packet filter or decode capabilities. However, you can use it in combination
with tcpdump for packet decoding.
Prerequisites
A network driver that supports XDP programs.
An XDP program is loaded to the enp1s0 interface. If no program is loaded, xdpdump captures
packets in a similar way tcpdump does, for backward compatibility.
Procedure
1. To capture packets on the enp1s0 interface and write them to the /root/capture.pcap file,
enter:
# xdpdump -i enp1s0 -w /root/capture.pcap
2. To stop capturing packets, press Ctrl+C.
Additional resources
xdpdump(8) man page
If you are a developer and you are interested in the source code of xdpdump, download and
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CHAPTER 41. UNDERSTANDING THE EBPF NETWORKING
FEATURES IN RHEL 9
The extended Berkeley Packet Filter (eBPF) is an in-kernel virtual machine that allows code execution in
the kernel space. This code runs in a restricted sandbox environment with access only to a limited set of
functions.
In networking, you can use eBPF to complement or replace kernel packet processing. Depending on the
hook you use, eBPF programs have, for example:
Read and write access to packet data and metadata
Can look up sockets and routes
Can set socket options
Can redirect packets
41.1. OVERVIEW OF NETWORKING EBPF FEATURES IN RHEL 9
You can attach extended Berkeley Packet Filter (eBPF) networking programs to the following hooks in
RHEL:
eXpress Data Path (XDP): Provides early access to received packets before the kernel
networking stack processes them.
tc eBPF classifier with direct-action flag: Provides powerful packet processing on ingress and
egress.
Control Groups version 2 (cgroup v2): Enables filtering and overriding socket-based operations
performed by programs in a control group.
Socket filtering: Enables filtering of packets received from sockets. This feature was also
available in the classic Berkeley Packet Filter (cBPF), but has been extended to support eBPF
programs.
Stream parser: Enables splitting up streams to individual messages, filtering, and redirecting
them to sockets.
SO_REUSEPORT socket selection: Provides a programmable selection of a receiving socket
from a reuseport socket group.
Flow dissector: Enables overriding the way the kernel parses packet headers in certain
situations.
TCP congestion control callbacks: Enables implementing a custom TCP congestion control
algorithm.
Routes with encapsulation: Enables creating custom tunnel encapsulation.
XDP
You can attach programs of the BPF_PROG_TYPE_XDP type to a network interface. The kernel then
executes the program on received packets before the kernel network stack starts processing them. This
allows fast packet forwarding in certain situations, such as fast packet dropping to prevent distributed
denial of service (DDoS) attacks and fast packet redirects for load balancing scenarios.
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You can also use XDP for different forms of packet monitoring and sampling. The kernel allows XDP
programs to modify packets and to pass them for further processing to the kernel network stack.
The following XDP modes are available:
Native (driver) XDP: The kernel executes the program from the earliest possible point during
packet reception. At this moment, the kernel did not parse the packet and, therefore, no
metadata provided by the kernel is available. This mode requires that the network interface
driver supports XDP but not all drivers support this native mode.
Generic XDP: The kernel network stack executes the XDP program early in the processing. At
that time, kernel data structures have been allocated, and the packet has been pre-processed. If
a packet should be dropped or redirected, it requires a significant overhead compared to the
native mode. However, the generic mode does not require network interface driver support and
works with all network interfaces.
Offloaded XDP: The kernel executes the XDP program on the network interface instead of on
the host CPU. Note that this requires specific hardware, and only certain eBPF features are
available in this mode.
On RHEL, load all XDP programs using the libxdp library. This library enables system-controlled usage
of XDP.
NOTE
Currently, there are some system configuration limitations for XDP programs. For
example, you must disable certain hardware offload features on the receiving interface.
Additionally, not all features are available with all drivers that support the native mode.
In RHEL 9, Red Hat supports the XDP features only if you use the libxdp library to load the program
into the kernel.
AF_XDP
Using an XDP program that filters and redirects packets to a given AF_XDP socket, you can use one or
more sockets from the AF_XDP protocol family to quickly copy packets from the kernel to the user
space.
Traffic Control
The Traffic Control (tc) subsystem offers the following types of eBPF programs:
BPF_PROG_TYPE_SCHED_CLS
BPF_PROG_TYPE_SCHED_ACT
These types enable you to write custom tc classifiers and tc actions in eBPF. Together with the parts of
the tc ecosystem, this provides the ability for powerful packet processing and is the core part of several
container networking orchestration solutions.
In most cases, only the classifier is used, as with the direct-action flag, the eBPF classifier can execute
actions directly from the same eBPF program. The clsact Queueing Discipline (qdisc) has been
designed to enable this on the ingress side.
Note that using a flow dissector eBPF program can influence operation of some other qdiscs and tc
classifiers, such as flower.
Socket filter
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Several utilities use or have used the classic Berkeley Packet Filter (cBPF) for filtering packets received
on a socket. For example, the tcpdump utility enables the user to specify expressions, which tcpdump
then translates into cBPF code.
As an alternative to cBPF, the kernel allows eBPF programs of the
BPF_PROG_TYPE_SOCKET_FILTER type for the same purpose.
Control Groups
In RHEL, you can use multiple types of eBPF programs that you can attach to a cgroup. The kernel
executes these programs when a program in the given cgroup performs an operation. Note that you can
use only cgroups version 2.
The following networking-related cgroup eBPF programs are available in RHEL:
BPF_PROG_TYPE_SOCK_OPS: The kernel calls this program on various TCP events. The
program can adjust the behavior of the kernel TCP stack, including custom TCP header options,
and so on.
BPF_PROG_TYPE_CGROUP_SOCK_ADDR: The kernel calls this program during connect,
bind, sendto, recvmsg, getpeername, and getsockname operations. This program allows
changing IP addresses and ports. This is useful when you implement socket-based network
address translation (NAT) in eBPF.
BPF_PROG_TYPE_CGROUP_SOCKOPT: The kernel calls this program during setsockopt
and getsockopt operations and allows changing the options.
BPF_PROG_TYPE_CGROUP_SOCK: The kernel calls this program during socket creation,
socket releasing, and binding to addresses. You can use these programs to allow or deny the
operation, or only to inspect socket creation for statistics.
BPF_PROG_TYPE_CGROUP_SKB: This program filters individual packets on ingress and
egress, and can accept or reject packets.
BPF_PROG_TYPE_CGROUP_SYSCTL: This program allows filtering of access to system
controls (sysctl).
Stream Parser
A stream parser operates on a group of sockets that are added to a special eBPF map. The eBPF
program then processes packets that the kernel receives or sends on those sockets.
The following stream parser eBPF programs are available in RHEL:
BPF_PROG_TYPE_SK_SKB: An eBPF program parses packets received from the socket into
individual messages, and instructs the kernel to drop those messages or send them to another
socket in the group.
BPF_PROG_TYPE_SK_MSG: This program filters egress messages. An eBPF program parses
the packets into individual messages and either approves or rejects them.
SO_REUSEPORT socket selection
Using this socket option, you can bind multiple sockets to the same IP address and port. Without eBPF,
the kernel selects the receiving socket based on a connection hash. With the
BPF_PROG_TYPE_SK_REUSEPORT program, the selection of the receiving socket is fully
programmable.
Flow dissector
When the kernel needs to process packet headers without going through the full protocol decode, they
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are dissected. For example, this happens in the tc subsystem, in multipath routing, in bonding, or when
calculating a packet hash. In this situation the kernel parses the packet headers and fills internal
structures with the information from the packet headers. You can replace this internal parsing using the
BPF_PROG_TYPE_FLOW_DISSECTOR program. Note that you can only dissect TCP and UDP over
IPv4 and IPv6 in eBPF in RHEL.
TCP Congestion Control
You can write a custom TCP congestion control algorithm using a group of
BPF_PROG_TYPE_STRUCT_OPS programs that implement struct tcp_congestion_oops callbacks.
An algorithm that is implemented this way is available to the system alongside the built-in kernel
algorithms.
Routes with encapsulation
You can attach one of the following eBPF program types to routes in the routing table as a tunnel
encapsulation attribute:
BPF_PROG_TYPE_LWT_IN
BPF_PROG_TYPE_LWT_OUT
BPF_PROG_TYPE_LWT_XMIT
The functionality of such an eBPF program is limited to specific tunnel configurations and does not allow
creating a generic encapsulation or decapsulation solution.
Socket lookup
To bypass limitations of the bind system call, use an eBPF program of the
BPF_PROG_TYPE_SK_LOOKUP type. Such programs can select a listening socket for new incoming
TCP connections or an unconnected socket for UDP packets.
41.2. OVERVIEW OF XDP FEATURES IN RHEL 9 BY NETWORK CARDS
The following is an overview of XDP-enabled network cards and the XDP features you can use with
them:
Network card Driver Basic Redir
ect
Targ
et
HW
offlo
ad
Zero
-
copy
Larg
e
MTU
Amazon Elastic Network Adapter ena yes yes yes
[a]
no no no
aQuantia AQtion Ethernet card atlantic yes yes no no no no
Broadcom NetXtreme-C/E
10/25/40/50 gigabit Ethernet
bnxt_en yes yes yes
[a]
no no yes
Cavium Thunder Virtual function nicvf yes no no no no no
Google Virtual NIC (gVNIC)
support
gve yes yes yes no yes no
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Intel® 10GbE PCI Express Virtual
Function Ethernet
ixgbevf yes no no no no no
Intel® 10GbE PCI Express adapters ixgbe yes yes yes
[a]
no yes yes
[b]
Intel® Ethernet Connection E800
Series
ice yes yes yes
[a]
no yes yes
Intel® Ethernet Controller I225-
LM/I225-V family
igc yes yes yes no yes yes
[b]
Intel® PCI Express Gigabit adapters igb yes yes yes
[a]
no no yes
[b]
Intel® Ethernet Controller XL710
Family
i40e yes yes yes
[a]
[c]
no yes no
Marvell OcteonTX2 rvu_nicpf yes yes yes
[a]
[c]
no no no
Mellanox 5th generation network
adapters (ConnectX series)
mlx5_core yes yes yes
[c]
no yes yes
Mellanox Technologies
1/10/40Gbit Ethernet
mlx4_en yes yes no no no no
Microsoft Azure Network Adapter mana yes yes yes no no no
Microsoft Hyper-V virtual network hv_netvsc yes yes yes no no no
Netronome® NFP4000/NFP6000
NIC
[d]
nfp yes no no yes yes no
QEMU Virtio network virtio_net yes yes yes
[a]
no no yes
QLogic QED 25/40/100Gb
Ethernet NIC
qede yes yes yes no no no
STMicroelectronics Multi-Gigabit
Ethernet
stmmac yes yes yes no yes no
Network card Driver Basic Redir
ect
Targ
et
HW
offlo
ad
Zero
-
copy
Larg
e
MTU
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Solarflare
SFC9000/SFC9100/EF100-family
sfc yes yes yes
[c]
no no no
Universal TUN/TAP device tun yes yes yes no no no
Virtual Ethernet pair device veth yes yes yes no no yes
VMware VMXNET3 ethernet driver vmxnet3 yes yes yes
[a]
[c]
no no no
Xen paravirtual network device xen-netfront yes yes yes no no no
[a]
Only if an XDP program is loaded on the interface.
[b]
Transmitting side only. Cannot receive large packets through XDP.
[c]
Requires several XDP TX queues allocated that is larger or equal to the largest CPU index.
[d]
Some of the listed features are not available for the Netronome® NFP3800 NIC.
Network card Driver Basic Redir
ect
Targ
et
HW
offlo
ad
Zero
-
copy
Larg
e
MTU
Legend:
Basic: Supports basic return codes: DROP, PASS, ABORTED, and TX.
Redirect: Supports the XDP_REDIRECT return code.
Target: Can be a target of a XDP_REDIRECT return code.
HW offload: Supports XDP hardware offload.
Zero-copy: Supports the zero-copy mode for the AF_XDP protocol family.
Large MTU: Supports packets larger than page size.
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CHAPTER 42. NETWORK TRACING USING THE BPF
COMPILER COLLECTION
BPF Compiler Collection (BCC) is a library, which facilitates the creation of the extended Berkeley
Packet Filter (eBPF) programs. The main utility of eBPF programs is analyzing the operating system
performance and network performance without experiencing overhead or security issues.
BCC removes the need for users to know deep technical details of eBPF, and provides many out-of-
the-box starting points, such as the bcc-tools package with pre-created eBPF programs.
NOTE
The eBPF programs are triggered on events, such as disk I/O, TCP connections, and
process creations. It is unlikely that the programs should cause the kernel to crash, loop or
become unresponsive because they run in a safe virtual machine in the kernel.
42.1. INSTALLING THE BCC-TOOLS PACKAGE
Install the bcc-tools package, which also installs the BPF Compiler Collection (BCC) library as a
dependency.
Procedure
1. Install bcc-tools.
# dnf install bcc-tools
The BCC tools are installed in the /usr/share/bcc/tools/ directory.
Verification
1. Inspect the installed tools:
# ll /usr/share/bcc/tools/
...
-rwxr-xr-x. 1 root root 4198 Dec 14 17:53 dcsnoop
-rwxr-xr-x. 1 root root 3931 Dec 14 17:53 dcstat
-rwxr-xr-x. 1 root root 20040 Dec 14 17:53 deadlock_detector
-rw-r--r--. 1 root root 7105 Dec 14 17:53 deadlock_detector.c
drwxr-xr-x. 3 root root 8192 Mar 11 10:28 doc
-rwxr-xr-x. 1 root root 7588 Dec 14 17:53 execsnoop
-rwxr-xr-x. 1 root root 6373 Dec 14 17:53 ext4dist
-rwxr-xr-x. 1 root root 10401 Dec 14 17:53 ext4slower
...
The doc directory in the listing above contains documentation for each tool.
42.2. DISPLAYING TCP CONNECTIONS ADDED TO THE KERNEL’S
ACCEPT QUEUE
After the kernel receives the ACK packet in a TCP 3-way handshake, the kernel moves the connection
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After the kernel receives the ACK packet in a TCP 3-way handshake, the kernel moves the connection
from the SYN queue to the accept queue after the connection’s state changes to ESTABLISHED.
Therefore, only successful TCP connections are visible in this queue.
The tcpaccept utility uses eBPF features to display all connections the kernel adds to the accept
queue. The utility is lightweight because it traces the accept() function of the kernel instead of
capturing packets and filtering them. For example, use tcpaccept for general troubleshooting to display
new connections the server has accepted.
Procedure
1. Enter the following command to start the tracing the kernel accept queue:
# /usr/share/bcc/tools/tcpaccept
PID COMM IP RADDR RPORT LADDR LPORT
843 sshd 4 192.0.2.17 50598 192.0.2.1 22
1107 ns-slapd 4 198.51.100.6 38772 192.0.2.1 389
1107 ns-slapd 4 203.0.113.85 38774 192.0.2.1 389
...
Each time the kernel accepts a connection, tcpaccept displays the details of the connections.
2. Press Ctrl+C to stop the tracing process.
Additional resources
tcpaccept(8) man page
/usr/share/bcc/tools/doc/tcpaccept_example.txt file
42.3. TRACING OUTGOING TCP CONNECTION ATTEMPTS
The tcpconnect utility uses eBPF features to trace outgoing TCP connection attempts. The output of
the utility also includes connections that failed.
The tcpconnect utility is lightweight because it traces, for example, the connect() function of the kernel
instead of capturing packets and filtering them.
Procedure
1. Enter the following command to start the tracing process that displays all outgoing connections:
# /usr/share/bcc/tools/tcpconnect
PID COMM IP SADDR DADDR DPORT
31346 curl 4 192.0.2.1 198.51.100.16 80
31348 telnet 4 192.0.2.1 203.0.113.231 23
31361 isc-worker00 4 192.0.2.1 192.0.2.254 53
...
Each time the kernel processes an outgoing connection, tcpconnect displays the details of the
connections.
2. Press Ctrl+C to stop the tracing process.
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Additional resources
tcpconnect(8) man page
/usr/share/bcc/tools/doc/tcpconnect_example.txt file
42.4. MEASURING THE LATENCY OF OUTGOING TCP CONNECTIONS
The TCP connection latency is the time taken to establish a connection. This typically involves the
kernel TCP/IP processing and network round trip time, and not the application runtime.
The tcpconnlat utility uses eBPF features to measure the time between a sent SYN packet and the
received response packet.
Procedure
1. Start measuring the latency of outgoing connections:
# /usr/share/bcc/tools/tcpconnlat
PID COMM IP SADDR DADDR DPORT LAT(ms)
32151 isc-worker00 4 192.0.2.1 192.0.2.254 53 0.60
32155 ssh 4 192.0.2.1 203.0.113.190 22 26.34
32319 curl 4 192.0.2.1 198.51.100.59 443 188.96
...
Each time the kernel processes an outgoing connection, tcpconnlat displays the details of the
connection after the kernel receives the response packet.
2. Press Ctrl+C to stop the tracing process.
Additional resources
tcpconnlat(8) man page
/usr/share/bcc/tools/doc/tcpconnlat_example.txt file
42.5. DISPLAYING DETAILS ABOUT TCP PACKETS AND SEGMENTS
THAT WERE DROPPED BY THE KERNEL
The tcpdrop utility enables administrators to display details about TCP packets and segments that were
dropped by the kernel. Use this utility to debug high rates of dropped packets that can cause the
remote system to send timer-based retransmits. High rates of dropped packets and segments can
impact the performance of a server.
Instead of capturing and filtering packets, which is resource-intensive, the tcpdrop utility uses eBPF
features to retrieve the information directly from the kernel.
Procedure
1. Enter the following command to start displaying details about dropped TCP packets and
segments:
# /usr/share/bcc/tools/tcpdrop
TIME PID IP SADDR:SPORT > DADDR:DPORT STATE (FLAGS)
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13:28:39 32253 4 192.0.2.85:51616 > 192.0.2.1:22 CLOSE_WAIT (FIN|ACK)
b'tcp_drop+0x1'
b'tcp_data_queue+0x2b9'
...
13:28:39 1 4 192.0.2.85:51616 > 192.0.2.1:22 CLOSE (ACK)
b'tcp_drop+0x1'
b'tcp_rcv_state_process+0xe2'
...
Each time the kernel drops TCP packets and segments, tcpdrop displays the details of the
connection, including the kernel stack trace that led to the dropped package.
2. Press Ctrl+C to stop the tracing process.
Additional resources
tcpdrop(8) man page
/usr/share/bcc/tools/doc/tcpdrop_example.txt file
42.6. TRACING TCP SESSIONS
The tcplife utility uses eBPF to trace TCP sessions that open and close, and prints a line of output to
summarize each one. Administrators can use tcplife to identify connections and the amount of
transferred traffic.
For example, you can display connections to port 22 (SSH) to retrieve the following information:
The local process ID (PID)
The local process name
The local IP address and port number
The remote IP address and port number
The amount of received and transmitted traffic in KB.
The time in milliseconds the connection was active
Procedure
1. Enter the following command to start the tracing of connections to the local port 22:
/usr/share/bcc/tools/tcplife -L 22
PID COMM LADDR LPORT RADDR RPORT TX_KB RX_KB MS
19392 sshd 192.0.2.1 22 192.0.2.17 43892 53 52 6681.95
19431 sshd 192.0.2.1 22 192.0.2.245 43902 81 249381 7585.09
19487 sshd 192.0.2.1 22 192.0.2.121 43970 6998 7 16740.35
...
Each time a connection is closed, tcplife displays the details of the connections.
2. Press Ctrl+C to stop the tracing process.
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Additional resources
tcplife(8) man page
/usr/share/bcc/tools/doc/tcplife_example.txt file
42.7. TRACING TCP RETRANSMISSIONS
The tcpretrans utility displays details about TCP retransmissions, such as the local and remote IP
address and port number, as well as the TCP state at the time of the retransmissions.
The utility uses eBPF features and, therefore, has a very low overhead.
Procedure
1. Use the following command to start displaying TCP retransmission details:
# /usr/share/bcc/tools/tcpretrans
TIME PID IP LADDR:LPORT T> RADDR:RPORT STATE
00:23:02 0 4 192.0.2.1:22 R> 198.51.100.0:26788 ESTABLISHED
00:23:02 0 4 192.0.2.1:22 R> 198.51.100.0:26788 ESTABLISHED
00:45:43 0 4 192.0.2.1:22 R> 198.51.100.0:17634 ESTABLISHED
...
Each time the kernel calls the TCP retransmit function, tcpretrans displays the details of the
connection.
2. Press Ctrl+C to stop the tracing process.
Additional resources
tcpretrans(8) man page
/usr/share/bcc/tools/doc/tcpretrans_example.txt file
42.8. DISPLAYING TCP STATE CHANGE INFORMATION
During a TCP session, the TCP state changes. The tcpstates utility uses eBPF functions to trace these
state changes, and prints details including the duration in each state. For example, use tcpstates to
identify if connections spend too much time in the initialization state.
Procedure
1. Use the following command to start tracing TCP state changes:
# /usr/share/bcc/tools/tcpstates
SKADDR C-PID C-COMM LADDR LPORT RADDR RPORT OLDSTATE ->
NEWSTATE MS
ffff9cd377b3af80 0 swapper/1 0.0.0.0 22 0.0.0.0 0 LISTEN -> SYN_RECV
0.000
ffff9cd377b3af80 0 swapper/1 192.0.2.1 22 192.0.2.45 53152 SYN_RECV ->
ESTABLISHED 0.067
ffff9cd377b3af80 818 sssd_nss 192.0.2.1 22 192.0.2.45 53152 ESTABLISHED ->
CLOSE_WAIT 65636.773
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ffff9cd377b3af80 1432 sshd 192.0.2.1 22 192.0.2.45 53152 CLOSE_WAIT ->
LAST_ACK 24.409
ffff9cd377b3af80 1267 pulseaudio 192.0.2.1 22 192.0.2.45 53152 LAST_ACK ->
CLOSE 0.376
...
Each time a connection changes its state, tcpstates displays a new line with updated connection
details.
If multiple connections change their state at the same time, use the socket address in the first
column (SKADDR) to determine which entries belong to the same connection.
2. Press Ctrl+C to stop the tracing process.
Additional resources
tcpstates(8) man page
/usr/share/bcc/tools/doc/tcpstates_example.txt file
42.9. SUMMARIZING AND AGGREGATING TCP TRAFFIC SENT TO
SPECIFIC SUBNETS
The tcpsubnet utility summarizes and aggregates IPv4 TCP traffic that the local host sends to subnets
and displays the output on a fixed interval. The utility uses eBPF features to collect and summarize the
data to reduce the overhead.
By default, tcpsubnet summarizes traffic for the following subnets:
127.0.0.1/32
10.0.0.0/8
172.16.0.0/12
192.0.2.0/24/16
0.0.0.0/0
Note that the last subnet (0.0.0.0/0) is a catch-all option. The tcpsubnet utility counts all traffic for
subnets different than the first four in this catch-all entry.
Follow the procedure to count the traffic for the 192.0.2.0/24 and 198.51.100.0/24 subnets. Traffic to
other subnets will be tracked in the 0.0.0.0/0 catch-all subnet entry.
Procedure
1. Start monitoring the amount of traffic send to the 192.0.2.0/24, 198.51.100.0/24, and other
subnets:
# /usr/share/bcc/tools/tcpsubnet 192.0.2.0/24,198.51.100.0/24,0.0.0.0/0
Tracing... Output every 1 secs. Hit Ctrl-C to end
[02/21/20 10:04:50]
192.0.2.0/24 856
198.51.100.0/24 7467
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[02/21/20 10:04:51]
192.0.2.0/24 1200
198.51.100.0/24 8763
0.0.0.0/0 673
...
This command displays the traffic in bytes for the specified subnets once per second.
2. Press Ctrl+C to stop the tracing process.
Additional resources
tcpsubnet(8) man page
/usr/share/bcc/tools/doc/tcpsubnet.txt file
42.10. DISPLAYING THE NETWORK THROUGHPUT BY IP ADDRESS
AND PORT
The tcptop utility displays TCP traffic the host sends and receives in kilobytes. The report automatically
refreshes and contains only active TCP connections. The utility uses eBPF features and, therefore, has
only a very low overhead.
Procedure
1. To monitor the sent and received traffic, enter:
# /usr/share/bcc/tools/tcptop
13:46:29 loadavg: 0.10 0.03 0.01 1/215 3875
PID COMM LADDR RADDR RX_KB TX_KB
3853 3853 192.0.2.1:22 192.0.2.165:41838 32 102626
1285 sshd 192.0.2.1:22 192.0.2.45:39240 0 0
...
The output of the command includes only active TCP connections. If the local or remote system
closes a connection, the connection is no longer visible in the output.
2. Press Ctrl+C to stop the tracing process.
Additional resources
tcptop(8) man page
/usr/share/bcc/tools/doc/tcptop.txt file
42.11. TRACING ESTABLISHED TCP CONNECTIONS
The tcptracer utility traces the kernel functions that connect, accept, and close TCP connections. The
utility uses eBPF features and, therefore, has a very low overhead.
Procedure
1. Use the following command to start the tracing process:
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# /usr/share/bcc/tools/tcptracer
Tracing TCP established connections. Ctrl-C to end.
T PID COMM IP SADDR DADDR SPORT DPORT
A 1088 ns-slapd 4 192.0.2.153 192.0.2.1 0 65535
A 845 sshd 4 192.0.2.1 192.0.2.67 22 42302
X 4502 sshd 4 192.0.2.1 192.0.2.67 22 42302
...
Each time the kernel connects, accepts, or closes a connection, tcptracer displays the details of
the connections.
2. Press Ctrl+C to stop the tracing process.
Additional resources
tcptracer(8) man page
/usr/share/bcc/tools/doc/tcptracer_example.txt file
42.12. TRACING IPV4 AND IPV6 LISTEN ATTEMPTS
The solisten utility traces all IPv4 and IPv6 listen attempts. It traces the listen attempts including that
ultimately fail or the listening program that does not accept the connection. The utility traces function
that the kernel calls when a program wants to listen for TCP connections.
Procedure
1. Enter the following command to start the tracing process that displays all listen TCP attempts:
# /usr/share/bcc/tools/solisten
PID COMM PROTO BACKLOG PORT ADDR
3643 nc TCPv4 1 4242 0.0.0.0
3659 nc TCPv6 1 4242 2001:db8:1::1
4221 redis-server TCPv6 128 6379 ::
4221 redis-server TCPv4 128 6379 0.0.0.0
....
2. Press Ctrl+C to stop the tracing process.
Additional resources
solisten(9) man page
/usr/share/bcc/tools/doc/solisten_example.txt file
42.13. SUMMARIZING THE SERVICE TIME OF SOFT INTERRUPTS
The softirqs utility summarizes the time spent servicing soft interrupts (soft IRQs) and shows this time
as either totals or histogram distributions. This utility uses the irq:softirq_enter and irq:softirq_exit
kernel tracepoints, which is a stable tracing mechanism.
Procedure
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1. Enter the following command to start the tracing soft irq event time:
# /usr/share/bcc/tools/softirqs
Tracing soft irq event time... Hit Ctrl-C to end.
^C
SOFTIRQ TOTAL_usecs
tasklet 166
block 9152
net_rx 12829
rcu 53140
sched 182360
timer 306256
2. Press Ctrl+C to stop the tracing process.
Additional resources
softirqs(8) man page
/usr/share/bcc/tools/doc/softirqs_example.txt file
mpstat(1) man page
42.14. SUMMARIZING PACKETS SIZE AND COUNT ON A NETWORK
INTERFACE
The netqtop utility displays statistics about the attributes of received (RX) and transmitted (TX)
packets on each network queue of a particular network interface. The statistics include:
Bytes per second (BPS)
Packets per second (PPS)
The average packet size
Total number of packets
To generate these statistics, netqtop traces the kernel functions that perform events of transmitted
packets net_dev_start_xmit and received packets netif_receive_skb.
Procedure
1. Display the number of packets within the range of bytes size of the time interval of 2 seconds:
# /usr/share/bcc/tools/netqtop -n enp1s0 -i 2
Fri Jan 31 18:08:55 2023
TX
QueueID avg_size [0, 64) [64, 512) [512, 2K) [2K, 16K) [16K, 64K)
0 0 0 0 0 0 0
Total 0 0 0 0 0 0
RX
QueueID avg_size [0, 64) [64, 512) [512, 2K) [2K, 16K) [16K, 64K)
0 38.0 1 0 0 0 0
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Total 38.0 1 0 0 0 0
-----------------------------------------------------------------------------
Fri Jan 31 18:08:57 2023
TX
QueueID avg_size [0, 64) [64, 512) [512, 2K) [2K, 16K) [16K, 64K)
0 0 0 0 0 0 0
Total 0 0 0 0 0 0
RX
QueueID avg_size [0, 64) [64, 512) [512, 2K) [2K, 16K) [16K, 64K)
0 38.0 1 0 0 0 0
Total 38.0 1 0 0 0 0
-----------------------------------------------------------------------------
2. Press Ctrl+C to stop netqtop.
Additional resources
netqtop(8) man page
/usr/share/bcc/tools/doc/netqtop_example.txt
42.15. ADDITIONAL RESOURCES
/usr/share/doc/bcc/README.md
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CHAPTER 43. CONFIGURING NETWORK DEVICES TO ACCEPT
TRAFFIC FROM ALL MAC ADDRESSES
Network devices usually intercept and read packets that their controller is programmed to receive. You
can configure the network devices to accept traffic from all MAC addresses in a virtual switch or at the
port group level.
You can use this network mode to:
Diagnose network connectivity issues
Monitor network activity for security reasons
Intercept private data-in-transit or intrusion in the network
You can enable this mode for any kind of network device, except InfiniBand.
43.1. TEMPORARILY CONFIGURING A DEVICE TO ACCEPT ALL
TRAFFIC
You can use the ip utility to temporary configure a network device to accept all traffic regardless of the
MAC addresses.
Procedure
1. Optional: Display the network interfaces to identify the one for which you want to receive all
traffic:
# ip address show
1: enp1s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state
DOWN group default qlen 1000
link/ether 98:fa:9b:a4:34:09 brd ff:ff:ff:ff:ff:ff
...
2. Modify the device to enable or disable this property:
To enable the accept-all-mac-addresses mode for enp1s0:
# ip link set enp1s0 promisc on
To disable the accept-all-mac-addresses mode for enp1s0:
# ip link set enp1s0 promisc off
Verification
Verify that the accept-all-mac-addresses mode is enabled:
# ip link show enp1s0
1: enp1s0: <NO-CARRIER,BROADCAST,MULTICAST,PROMISC,UP> mtu 1500 qdisc
fq_codel state DOWN mode DEFAULT group default qlen 1000
link/ether 98:fa:9b:a4:34:09 brd ff:ff:ff:ff:ff:ff
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The PROMISC flag in the device description indicates that the mode is enabled.
43.2. PERMANENTLY CONFIGURING A NETWORK DEVICE TO ACCEPT
ALL TRAFFIC USING NMCLI
You can use the nmcli utility to permanently configure a network device to accept all traffic regardless
of the MAC addresses.
Procedure
1. Optional: Display the network interfaces to identify the one for which you want to receive all
traffic:
# ip address show
1: enp1s0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state
DOWN group default qlen 1000
link/ether 98:fa:9b:a4:34:09 brd ff:ff:ff:ff:ff:ff
...
You can create a new connection, if you do not have any.
2. Modify the network device to enable or disable this property.
To enable the ethernet.accept-all-mac-addresses mode for enp1s0:
# nmcli connection modify enp1s0 ethernet.accept-all-mac-addresses yes
To disable the accept-all-mac-addresses mode for enp1s0:
# nmcli connection modify enp1s0 ethernet.accept-all-mac-addresses no
3. Apply the changes, reactivate the connection:
# nmcli connection up enp1s0
Verification
Verify that the ethernet.accept-all-mac-addresses mode is enabled:
# nmcli connection show enp1s0
...
802-3-ethernet.accept-all-mac-addresses:1 (true)
The 802-3-ethernet.accept-all-mac-addresses: true indicates that the mode is enabled.
43.3. PERMANENTLY CONFIGURING A NETWORK DEVICE TO ACCEPT
ALL TRAFFIC USING NMSTATECTL
Use the nmstatectl utility to configure a device to accept all traffic regardless of the MAC addresses
through the Nmstate API. The Nmstate API ensures that, after setting the configuration, the result
matches the configuration file. If anything fails, nmstatectl automatically rolls back the changes to avoid
leaving the system in an incorrect state.
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381
Prerequisites
The nmstate package is installed.
The enp1s0.yml file that you used to configure the device is available.
Procedure
1. Edit the existing enp1s0.yml file for the enp1s0 connection and add the following content to it:
These settings configure the enp1s0 device to accept all traffic.
2. Apply the network settings:
# nmstatectl apply ~/enp1s0.yml
Verification
Verify that the 802-3-ethernet.accept-all-mac-addresses mode is enabled:
# nmstatectl show enp1s0
interfaces:
- name: enp1s0
type: ethernet
state: up
accept-all-mac-addresses: true
...
The 802-3-ethernet.accept-all-mac-addresses: true indicates that the mode is enabled.
Additional resources
nmstatectl(8) man page
/usr/share/doc/nmstate/examples/ directory
---
interfaces:
- name: enp1s0
type: ethernet
state: up
accept -all-mac-address: true
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CHAPTER 44. MIRRORING A NETWORK INTERFACE BY USING
NMCLI
Network administrators can use port mirroring to replicate inbound and outbound network traffic being
communicated from one network device to another. Mirroring traffic of an interface can be helpful in the
following situations:
To debug networking issues and tune the network flow
To inspect and analyze the network traffic
To detect an intrusion
Prerequisites
A network interface to mirror the network traffic to.
Procedure
1. Add a network connection profile that you want to mirror the network traffic from:
# nmcli connection add type ethernet ifname enp1s0 con-name enp1s0 autoconnect
no
2. Attach a prio qdisc to enp1s0 for the egress (outgoing) traffic with the 10: handle:
# nmcli connection modify enp1s0 +tc.qdisc "root prio handle 10:"
The prio qdisc attached without children allows attaching filters.
3. Add a qdisc for the ingress traffic, with the ffff: handle:
# nmcli connection modify enp1s0 +tc.qdisc "ingress handle ffff:"
4. Add the following filters to match packets on the ingress and egress qdiscs, and to mirror them
to enp7s0:
# nmcli connection modify enp1s0 +tc.tfilter "parent ffff: matchall action mirred egress
mirror dev enp7s0"
# nmcli connection modify enp1s0 +tc.tfilter "parent 10: matchall action mirred egress
mirror dev enp7s0"
The matchall filter matches all packets, and the mirred action redirects packets to destination.
5. Activate the connection:
# nmcli connection up enp1s0
Verification
1. Install the tcpdump utility:
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CHAPTER 45. USING NMSTATE-AUTOCONF TO
AUTOMATICALLY CONFIGURE THE NETWORK STATE USING
LLDP
Network devices can use the Link Layer Discovery Protocol (LLDP) to advertise their identity,
capabilities, and neighbors in a LAN. The nmstate-autoconf utility can use this information to
automatically configure local network interfaces.
IMPORTANT
The nmstate-autoconf utility is provided as a Technology Preview only. Technology
Preview features are not supported with Red Hat production Service Level Agreements
(SLAs), might not be functionally complete, and Red Hat does not recommend using
them for production. These previews provide early access to upcoming product features,
enabling customers to test functionality and provide feedback during the development
process.
See Technology Preview Features Support Scope on the Red Hat Customer Portal for
information about the support scope for Technology Preview features.
45.1. USING NMSTATE-AUTOCONF TO AUTOMATICALLY CONFIGURE
NETWORK INTERFACES
The nmstate-autoconf utility uses LLDP to identify the VLAN settings of interfaces connected to a
switch to configure local devices.
This procedure assumes the following scenario and that the switch broadcasts the VLAN settings using
LLDP:
The enp1s0 and enp2s0 interfaces of the RHEL server are connected to switch ports that are
configured with VLAN ID 100 and VLAN name prod-net.
The enp3s0 interface of the RHEL server is connected to a switch port that is configured with
VLAN ID 200 and VLAN name mgmt-net.
The nmstate-autoconf utility then uses this information to create the following interfaces on the server:
bond100 - A bond interface with enp1s0 and enp2s0 as ports.
prod-net - A VLAN interface on top of bond100 with VLAN ID 100.
mgmt-net - A VLAN interface on top of enp3s0 with VLAN ID 200
If you connect multiple network interfaces to different switch ports for which LLDP broadcasts the same
VLAN ID, nmstate-autoconf creates a bond with these interfaces and, additionally, configures the
common VLAN ID on top of it.
Prerequisites
The nmstate package is installed.
LLDP is enabled on the network switch.
The Ethernet interfaces are up.
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Procedure
1. Enable LLDP on the Ethernet interfaces:
a. Create a YAML file, for example ~/enable-lldp.yml, with the following content:
b. Apply the settings to the system:
# nmstatectl apply ~/enable-lldp.yml
2. Configure the network interfaces using LLDP:
a. Optional, start a dry-run to display and verify the YAML configuration that nmstate-
autoconf generates:
# nmstate-autoconf -d enp1s0,enp2s0,enp3s0
---
interfaces:
- name: prod-net
type: vlan
state: up
vlan:
base-iface: bond100
id: 100
- name: mgmt-net
type: vlan
state: up
vlan:
base-iface: enp3s0
id: 200
- name: bond100
type: bond
state: up
link-aggregation:
mode: balance-rr
port:
- enp1s0
- enp2s0
b. Use nmstate-autoconf to generate the configuration based on information received from
LLDP, and apply the settings to the system:
interfaces:
- name: enp1s0
type: ethernet
lldp:
enabled: true
- name: enp2s0
type: ethernet
lldp:
enabled: true
- name: enp3s0
type: ethernet
lldp:
enabled: true
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# nmstate-autoconf enp1s0,enp2s0,enp3s0
Next steps
If there is no DHCP server in your network that provides the IP settings to the interfaces,
configure them manual. For details, see:
Configuring an Ethernet connection
Configuring a network bond
Verification
1. Display the settings of the individual interfaces:
# nmstatectl show <interface_name>
Additional resources
nmstate-autoconf(8) man page
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CHAPTER 46. CONFIGURING 802.3 LINK SETTINGS
Auto-negotiation is a feature of the IEEE 802.3u Fast Ethernet protocol. It targets the device ports to
provide an optimal performance of speed, duplex mode, and flow control for information exchange over
a link. Using the auto-negotiation protocol, you have optimal performance of data transfer over the
Ethernet.
NOTE
To utilize maximum performance of auto-negotiation, use the same configuration on
both sides of a link.
46.1. CONFIGURING 802.3 LINK SETTINGS USING THE NMCLI UTILITY
To configure the 802.3 link settings of an Ethernet connection, modify the following configuration
parameters:
802-3-ethernet.auto-negotiate
802-3-ethernet.speed
802-3-ethernet.duplex
Procedure
1. Display the current settings of the connection:
# nmcli connection show Example-connection
...
802-3-ethernet.speed: 0
802-3-ethernet.duplex: --
802-3-ethernet.auto-negotiate: no
...
You can use these values if you need to reset the parameters in case of any problems.
2. Set the speed and duplex link settings:
# nmcli connection modify Example-connection 802-3-ethernet.auto-negotiate yes 802-
3-ethernet.speed 10000 802-3-ethernet.duplex full
This command enables auto-negotiation and sets the speed of the connection to 10000 Mbit
full duplex.
3. Reactivate the connection:
# nmcli connection up Example-connection
Verification
Use the ethtool utility to verify the values of Ethernet interface enp1s0:
# ethtool enp1s0
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Settings for enp1s0:
...
Speed: 10000 Mb/s
Duplex: Full
Auto-negotiation: on
...
Link detected: yes
Additional resources
nm-settings(5) man page
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CHAPTER 47. GETTING STARTED WITH DPDK
The data plane development kit (DPDK) provides libraries and network drivers to accelerate packet
processing in user space.
Administrators use DPDK, for example, in virtual machines to use Single Root I/O Virtualization (SR-
IOV) to reduce latencies and increase I/O throughput.
NOTE
Red Hat does not support experimental DPDK APIs.
47.1. INSTALLING THE DPDK PACKAGE
To use DPDK, install the dpdk package.
Procedure
Use the dnf utility to install the dpdk package:
# dnf install dpdk
47.2. ADDITIONAL RESOURCES
Network Adapter Fast Datapath Feature Support Matrix
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CHAPTER 48. GETTING STARTED WITH TIPC
Transparent Inter-process Communication (TIPC), which is also known as Cluster Domain Sockets, is
an Inter-process Communication (IPC) service for cluster-wide operation.
Applications that are running in a high-available and dynamic cluster environment have special needs.
The number of nodes in a cluster can vary, routers can fail, and, due to load balancing considerations,
functionality can be moved to different nodes in the cluster. TIPC minimizes the effort by application
developers to deal with such situations, and maximizes the chance that they are handled in a correct and
optimal way. Additionally, TIPC provides a more efficient and fault-tolerant communication than general
protocols, such as TCP.
48.1. THE ARCHITECTURE OF TIPC
TIPC is a layer between applications using TIPC and a packet transport service (bearer), and spans the
level of transport, network, and signaling link layers. However, TIPC can use a different transport
protocol as bearer, so that, for example, a TCP connection can serve as a bearer for a TIPC signaling link.
TIPC supports the following bearers:
Ethernet
InfiniBand
UDP protocol
TIPC provides a reliable transfer of messages between TIPC ports, that are the endpoints of all TIPC
communication.
The following is a diagram of the TIPC architecture:
48.2. LOADING THE TIPC MODULE WHEN THE SYSTEM BOOTS
Before you can use the TIPC protocol, you must load the tipc kernel module. You can configure
Red Hat Enterprise Linux to automatically load this kernel module automatically when the system boots.
Procedure
1. Create the /etc/modules-load.d/tipc.conf file with the following content:
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tipc
2. Restart the systemd-modules-load service to load the module without rebooting the system:
# systemctl start systemd-modules-load
Verification
1. Use the following command to verify that RHEL loaded the tipc module:
# lsmod | grep tipc
tipc 311296 0
If the command shows no entry for the tipc module, RHEL failed to load it.
Additional resources
modules-load.d(5) man page
48.3. CREATING A TIPC NETWORK
To create a TIPC network, perform this procedure on each host that should join the TIPC network.
IMPORTANT
The commands configure the TIPC network only temporarily. To permanently configure
TIPC on a node, use the commands of this procedure in a script, and configure RHEL to
execute that script when the system boots.
Prerequisites
The tipc module has been loaded. For details, see Loading the tipc module when the system
boots
Procedure
1. Optional: Set a unique node identity, such as a UUID or the node’s host name:
# tipc node set identity host_name
The identity can be any unique string consisting of a maximum 16 letters and numbers.
You cannot set or change an identity after this step.
2. Add a bearer. For example, to use Ethernet as media and enp0s1 device as physical bearer
device, enter:
# tipc bearer enable media eth device enp1s0
3. Optional: For redundancy and better performance, attach further bearers using the command
from the previous step. You can configure up to three bearers, but not more than two on the
same media.
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4. Repeat all previous steps on each node that should join the TIPC network.
Verification
1. Display the link status for cluster members:
# tipc link list
broadcast-link: up
5254006b74be:enp1s0-525400df55d1:enp1s0: up
This output indicates that the link between bearer enp1s0 on node 5254006b74be and bearer
enp1s0 on node 525400df55d1 is up.
2. Display the TIPC publishing table:
# tipc nametable show
Type Lower Upper Scope Port Node
0 1795222054 1795222054 cluster 0 5254006b74be
0 3741353223 3741353223 cluster 0 525400df55d1
1 1 1 node 2399405586 5254006b74be
2 3741353223 3741353223 node 0 5254006b74be
The two entries with service type 0 indicate that two nodes are members of this cluster.
The entry with service type 1 represents the built-in topology service tracking service.
The entry with service type 2 displays the link as seen from the issuing node. The range limit
3741353223 represents the peer endpoint’s address (a unique 32-bit hash value based on
the node identity) in decimal format.
Additional resources
tipc-bearer(8) man page
tipc-namespace(8) man page
48.4. ADDITIONAL RESOURCES
Red Hat recommends to use other bearer level protocols to encrypt the communication
between nodes based on the transport media. For example:
MACSec: See Using MACsec to encrypt layer 2 traffic
IPsec: See Configuring a VPN with IPsec
For examples of how to use TIPC, clone the upstream GIT repository using the git clone
git://git.code.sf.net/p/tipc/tipcutils command. This repository contains the source code of
demos and test programs that use TIPC features. Note that this repository is not provided by
Red Hat.
/usr/share/doc/kernel-doc-<kernel_version>/Documentation/output/networking/tipc.html
provided by the kernel-doc package.
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CHAPTER 49. AUTOMATICALLY CONFIGURING NETWORK
INTERFACES IN PUBLIC CLOUDS USING NM-CLOUD-SETUP
Usually, a virtual machine (VM) has only one interface that is configurable by DHCP. However, DHCP
cannot configure VMs with multiple network entities, such as interfaces, IP subnets, and IP addresses.
Additionally, you cannot apply settings when the VM instance is running. To solve this runtime
configuration issue, the nm-cloud-setup utility automatically retrieves configuration information from
the metadata server of the cloud service provider and updates the network configuration of the host.
The utility automatically picks up multiple network interfaces, multiple IP addresses, or IP subnets on
one interface and helps to reconfigure the network of the running VM instance.
49.1. CONFIGURING AND PRE-DEPLOYING NM-CLOUD-SETUP
To enable and configure network interfaces in public clouds, run nm-cloud-setup as a timer and service.
NOTE
On Red Hat Enterprise Linux On Demand and AWS golden images, nm-cloud-setup is
already enabled and no action is required.
Prerequisite
A network connection exists.
The connection uses DHCP.
By default, NetworkManager creates a connection profile which uses DHCP. If no profile was
created because you set the no-auto-default parameter in
/etc/NetworkManager/NetworkManager.conf, create this initial connection manually.
Procedure
1. Install the nm-cloud-setup package:
# dnf install NetworkManager-cloud-setup
2. Create and run the snap-in file for the nm-cloud-setup service:
a. Use the following command to start editing the snap-in file:
# systemctl edit nm-cloud-setup.service
It is important to either start the service explicitly or reboot the system to make
configuration settings effective.
b. Use the systemd snap-in file to configure the cloud provider in nm-cloud-setup. For
example, to use Amazon EC2, enter:
[Service]
Environment=NM_CLOUD_SETUP_EC2=yes
You can set the following environment variables to enable the cloud provide you use:
NM_CLOUD_SETUP_AZURE for Microsoft Azure
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NM_CLOUD_SETUP_EC2 for Amazon EC2 (AWS)
NM_CLOUD_SETUP_GCP for Google Cloud Platform(GCP)
NM_CLOUD_SETUP_ALIYUN for Alibaba Cloud (Aliyun)
c. Save the file and quit the editor.
3. Reload the systemd configuration:
# systemctl daemon-reload
4. Enable and start the nm-cloud-setup service:
# systemctl enable --now nm-cloud-setup.service
5. Enable and start the nm-cloud-setup timer:
# systemctl enable --now nm-cloud-setup.timer
Additional resources
nm-cloud-setup(8) man page
Configuring an Ethernet connection
49.2. UNDERSTANDING THE ROLE OF IMDSV2 AND NM-CLOUD-
SETUP IN THE RHEL EC2 INSTANCE
The instance metadata service (IMDS) in Amazon EC2 allows you to manage permissions to access
instance metadata of a running Red Hat Enterprise Linux (RHEL) EC2 instance. The RHEL EC2 instance
uses IMDS version 2 (IMDSv2), a session-oriented method. By using the nm-cloud-setup utility,
administrators can reconfigure the network and automatically update the configuration of running RHEL
EC2 instances. The nm-cloud-setup utility handles IMDSv2 API calls by using IMDSv2 tokens without
any user intervention.
IMDS runs on a link-local address 169.254.169.254 for providing access to native applications
on a RHEL EC2 instance.
After you have specified and configured IMDSv2 for each RHEL EC2 instance for applications
and users, you can no longer access IMDSv1.
By using IMDSv2, the RHEL EC2 instance maintains metadata without using the IAM role while
remaining accessible through the IAM role.
When the RHEL EC2 instance boots, the nm-cloud-setup utility automatically runs to fetch the
EC2 instance API access token for using the RHEL EC2 instance API.
NOTE
Use the IMDSv2 token as an HTTP header to check the details of the EC2 environment.
Additional resources
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nm-cloud-setup(8) man page
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