mDNS Repeater and firewall rules

[Tubs]

Hello,

I want to use the mDNS repeater on OPNsense to forward mDNS between two subnets.
Out of the documentation it is not clear to me what firewall rules I need to allow the mDNS multicast traffic between these two vpn.

• on both interfaces to port 5353 at 224.0.0.251 and [ff02::fb] or
• on both interfaces to port 5353 at "subnet address" or
• on both interfaces to port 5353 at "this firewall"

Or a combination out of these three?

[dseven]

I haven't tried it, but I would expect that if you have the "Default allow LAN to any rule", it should "just work" (from LAN), but if you don't, you'd need something like your option (1).

[Tubs]

OK, I did not mentioned that these two vlans are isolated from each other by default and only inter vlan routing is possible where it explicitly is allowed by a firewall rule.

Yes, I just could make trial and error. But I want to understand what is right and what is wrong. That's why I am asking in the hope someone know the answer.