SNMP trap handling

Currently, librenms only supports linkUp/linkDown (port up/down), bgpEstablished/bgpBackwardTransition (BGP Sessions Up/Down) and authenticationFailure SNMP traps. To add more see Adding new SNMP Trap handlers

Traps are handled via snmptrapd.

Configure snmptrapd

Install snmptrapd via your package manager.

To enable snmptrapd to properly parse traps, we will need to add MIBs.

Make the folder /etc/systemd/system/snmptrapd.service.d/ and edit the file /etc/systemd/system/snmptrapd.service.d/mibs.conf and add the following content. You may want to tweak to add vendor directories for devices you care about (in addition to or instead of cisco).


For non-systemd systems, you can edit TRAPDOPTS in the init script in /etc/init.d/snmptrapd.

TRAPDOPTS="-Lsd -M /opt/librenms/mibs -m ALL -f -p $TRAPD_PID"

In /etc/snmp/snmptrapd.conf, add something like the following:

traphandle default /opt/librenms/snmptrap.php

Along with any necessary configuration to receive the traps from your devices (community, etc.)

Reload service files, enable, and start the snmptrapd service:

sudo systemctl daemon-reload
sudo systemctl enable snmptrapd
sudo systemctl restart snmptrapd

Event logging

You can configure generic event logging for snmp traps. This will log an event of the type trap for received traps. These events can be utilized for alerting.

In config.php

$config['snmptraps']['eventlog'] = 'unhandled';

Valid options are:

  • unhandled only unhandled traps will be logged
  • all log all traps
  • none no traps will create a generic event log (handled traps may still log events)