Chapter 31. 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. 31.1. 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: Updating modified connection settings without deactivation or restart of a network interface. 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. 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 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 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 on your system 31.2. 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 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 : Restart the systemd-journald service. Create the /etc/NetworkManager/conf.d/95-nm-debug.conf file with the following content: The domains parameter can contain multiple comma-separated domain:level pairs. Restart the NetworkManager service. Verification Query the systemd journal to display the journal entries of the NetworkManager unit: 31.3. Temporarily setting log levels at run time using nmcli You can change the log level at run time using nmcli . Procedure Optional: Display the current logging settings: To modify the logging level and domains, use the following options: To set the log level for all domains to the same LEVEL , enter: To change the level for specific domains, enter: 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: 31.4. Viewing NetworkManager logs You can view the NetworkManager logs for troubleshooting. Procedure To view the logs, enter: Additional resources NetworkManager.conf(5) and journalctl(1) man pages on your system 31.5. 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. Additional resources NetworkManager.conf(5) man page on your system

Commands:
RateLimitBurst=0
systemctl restart systemd-journald
[logging] domains=ALL:TRACE
systemctl restart NetworkManager
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
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,DEVICE,OLPC, WIMAX,INFINIBAND,FIREWALL,ADSL,BOND,VLAN,BRIDGE,DBUS_PROPS,TEAM,CONCHECK,DC B,DISPATCH
nmcli general logging level LEVEL domains ALL
nmcli general logging level LEVEL domains DOMAINS
nmcli general logging level KEEP domains DOMAIN:LEVEL , DOMAIN:LEVEL
journalctl -u NetworkManager -b