How to forward mDNS across VLANs in VyOS 1.4

[Ethernaut]

Hello,

In my network I have Apple HomeKit and AirPlay devices (in an IoT VLAN) and Apple clients (in a LAN VLAN). As you know, mDNS normally only works inside the same VLAN. On Cisco WLC I could use the mDNS Gateway, but in my current setup I want to do it with VyOS 1.4.

I know VyOS supports multicast routing (PIM-SM, IGMP proxy). I’ve also seen people use Avahi reflector on Linux to repeat mDNS between interfaces.

Question:

• What is the best way to forward mDNS (UDP 5353 / 224.0.0.251) between two VLANs in VyOS 1.4, so HomeKit devices can be discovered across VLANs?

• Has anyone here integrated Avahi with VyOS to act as an mDNS reflector for HomeKit/AirPlay?

Thanks!

[L0crian]

VyOS has a built in mDNS repeater capability:

l0crian@NPB7# set service mdns repeater 
Possible completions:
+  allow-service        Allowed mDNS services to be repeated
+  browse-domain        mDNS browsing domains in addition to the default one
   cache-entries        Number of resource records cached per interface (default: 4096)
   disable              Disable instance
+  interface            Interface to use
   ip-version           IP address version to use (default: both)
   vrrp-disable         Disables mDNS repeater on VRRP interfaces not in MASTER state

mDNS Repeater — VyOS 1.4.x (sagitta) documentation

[Ethernaut]

Hi L0crian,

Is it possible to create a policy, or is all traffic reflected by default?

Thanks

[L0crian]

You can’t create a policy in the sense you could have different interfaces in different policies. Everything effectively is a global policy. But you can scope what can be repeated with the allow-service config node.