OPNsense Forum

English Forums => 26.1, 26,4 Series => Topic started by: SimonS94 on May 02, 2026, 11:11:32 AM

Title: Can't start Dnsmasq when DHCRelays run
Post by: SimonS94 on May 02, 2026, 11:11:32 AM
I have Dnsmasq setup as a DHCP Server for some of my VLANs. I also have DHCRelay configured for some VLANs, that should get their IP from my Windows DomainControllers. The VLAN's don't overlap, i specifically set "No DHCP" on Dnsmasq for the VLANs that get relayed via DHCRelay.

Whenever I change something in Dnsmasq and the service (probably) restarts itself, it fails to start. and it says the DHCP Port is already in use. whenever i then just kill the DHCRealy, start DNSmasq and then start DHCRelays again, everything works. When I change something on Dnsmasq again, it fails to start again until i kill the DHCRelay.

How could I fix this?
Title: Re: Can't start Dnsmasq when DHCRelays run
Post by: Monviech (Cedrik) on May 02, 2026, 11:14:49 AM
Enable advanced mode in dnsmasq and use strict interface binding, and make sure the interfaces used for dnsmasq and dhcrelay dont overlap.

If thats not possible drop in a custom dnsmasq config file that configures a relay in dnsmasq instead.