SNMP monitoring - new process names when switching from ISC to Kea DHCP
-
I am using Zabbix 6.4 to monitor pfSense Plus 23.09 via SNMP. Switching from ISC DHCP to Kea DHCP immediately alerted on Zabbix that DHCP was down on the pfSense server.
Initially, I thought it was a blip due to a service restarting, and the SNMP check happening at the same time, but the alert didn't go away.
I knew it was a false alert because DHCP was clearly working, so I looked into the root cause of the false alert.The actual issue was that the ISC process name 'dhcpd' is replaced by 'kea-dhcp4' and 'kea-dhcp6', so the old process name isn't running anymore, and that is what Zabbix was looking for.
below is the basic snmpwalk to check the relevant OID:
% snmpwalk [pfsense-server] .1.3.6.1.2.1.25.4.2.1.2 | grep dhcp
HOST-RESOURCES-MIB::hrSWRunName.13707 = STRING: "kea-dhcp4"
HOST-RESOURCES-MIB::hrSWRunName.13916 = STRING: "kea-dhcp6"
HOST-RESOURCES-MIB::hrSWRunName.56040 = STRING: "dhcpleases"The correction needed is on the Zabbix side to look for the new processes (clone the DHCP monitoring template, change the SNMP OID check to look for the new process names, and disable the previous one.)
I am posting it on the pfSense SNMP forum as as FYI in case anyone else is monitoring pfSense DHCP service via SNMP since it would affect any SNMP monitor searching by process name when switching between ISC and Kea DHCP.