An mDNS repeater that can ran as a container on Mikrotik routers.

Based on:

Images availabe on Dockerhub at mag1024/mikrotik-docker-mdns-repeater.

As of Oct 2022, the Mikrotik container implementation is limited to exactly one network interface. There is no option for an equivalent of 'host' mode networking, and the interface must be of type veth, so we have to get creative to get a functional repeater. The key is to attach the venth to a trunk bridge that contains multiple vlans corresponding to the networks we want to repeat across, and then create interfaces for each of the vlans inside the container, using the veth as the parent. The set of vlans/interfaces to use is specified via the REPEATER_INTERFACES env variable, and the container runs a dhcp client to obtain an IP for each of them.

Begin by following the Mikrotik container documentation to create the veth interface. Instead of creating a separate docker bridge, assign the new interface as a 'tagged' port to the bridge containing the interfaces you wish to repeat across. These interfaces can be vlan interfaces, or physical interfaces with pvid set -- depending on whether you use vlans for the rest of your network setup. Refer to the Mikrotik bridge documentation for more details.

The following example uses veth-trunk veth interface and br-trunk bridge, configured with vlans 10, 11, 12.

Note: The address here does not matter, but it must have one to make the interface 'active'.

Note: Again, pvid of the veth itself does not matter.

Note: The name of the interface inside the container is always eth0.

Note: you may have to set the registry first via /container/config/set registry-url=https://registry-1.docker.io. Note: start-on-boot is only available on Mikrotik 7.6+