multicast-relay VS bonjour-reflector

IoT VLAN indeed can be annoying. It's getting better as a lot of the more "prosumer" grade routers are supporting it. I use Sonos at home too, which means I had to deploy this into a VM to bridge the VLANs: https://github.com/alsmith/multicast-relay.

There are some funny (?) things that turn up too, like learning the Roku remote iOS app "discovers" devices by opening a TCP connection to every address in parallel on its local /24 (!!!). It sends out and receives mDNS packets that would tell it exactly where they are, but they are ignored by the app.

github post

I want to use this Multicast Relay docker container to forward mDNS packages between my VLANS.

A lightweight alternative to Avahi is this multicast and SSDP relay script https://github.com/alsmith/multicast-relay

I have removed all firewall rules and set up multi-cast relay (https://github.com/alsmith/multicast-relay) and I can see the printer (a Canon PIXMA G3650) but setup fails from a mac on a separate VLAN. If I set up from same VLAN and print from there all is fine, but as soon as I am on a separate VLAN I cannot either setup or print.

If you know your way around Linux, you can still install things without docker. Like the multicast-relay OP wants to use is just a python package. So you would just need to install python first with apt-get, the dependencies, and just download the python package and run it.

From there just setup the firewall rules to not block sonos devices from establishing connections on another vlan follow the instructions at multicast relay github here https://github.com/alsmith/multicast-relay

Airprint uses Zeroconf/Bonjour, and this protocol is unrouted (i.e. only works on the local subnet), unfortunately it doesn’t work over different vlans. There’s a hack-ish way to get around it (“Bonjour reflection”, https://github.com/Gandem/bonjour-reflector ) you can try that.

Avahi is nifty for that however bonjour-reflector is on my list of things to play with for a little more fine-grained control over what people and devices are able to see on which network. For example, my guest wi-fi shouldn't be able to even see the chromecast in my bedroom. Even if firewall rules already prevent them from talking to it.

Find out more about the protocols in use. It might be mDNS/bonjour. At that point you can implement a reflector, for example bonjour-reflector https://github.com/Gandem/bonjour-reflector

You also will likely will have to enable Avahi, which at least on pfsense will echo everything between the interfaces it is enabled on. This isn't always desirable, there is some limited filtering possible in a more contemporary version of Avahi. bonjour-reflector is on my list of things to play with on a rainy day which should give me the granularity to expose one chromecast to my guest network and leave the rest locked up.