Ok I’ll take a look on that to see if it can be integrated in ZS.
I actually need something similar. I need multicast to forward over a LAN-to-LAN OpenVPN connection. It appears the ZeroShell kernel has the basic multicast routing enabled, but there’s some part of the equation that’s missing, perhaps a userspace multicast router like mrouter? If you check the /proc/sys/net/ipv4/mc_forwarding (approximate path, might be off a bit), it defaults to zero for each interface. You cannot set that setting manually, I think either a certain kernel flag is missing or only multicast routing user space apps can do it.