crosswind

crosswind is an IPv6 multicast bridge. Given an multicast IP address and the addresses of one or more other machines also running crosswind, it can rebroadcast link-local multicast traffic from one network to another. This is useful for e.g. having multicast traffic traverse your Tailscale tailnet (something that is not supported by Tailscale out of the box).

Using crosswind with Tailscale

If you just want to make a multicast address work across your tailnet, use the tailscale command:

cargo run --bin tailscale --\
    --multicast-address <IPv6 multicast address, including port number>

(This requires the Tailscale CLI to be installed locally.)

This will forward any multicast traffic received on the given address to each of the machines in your tailnet. If they are also running crosswind, they will re-broadcast this traffic back out on the same multicast address.

Using crosswind directly

For other use cases or more fine-grained control, you can run crosswind directly:

cargo run --\
    --interface <interface name or local IP address>\
    --multicast-address <IPv6 multicast address, including port number>\
    --targets <IPv6 address + port number of other crosswind instance>\
    --targets <IPv6 address + port number of yet another crosswind instance>\
    --targets <...and so on>\
    --port <port number to listen on; default is 9908>