Ubuntu – Manual Multicast forwarding with Linux router

forwardingmulticastrouterUbuntu

I have a Linux router (Ubuntu). It is working well with unicast but with multicast routing/forwarding I have some trouble.

The problem is that my hosts do not send igmp/mld messages thus the router does not learn that there are interested parties on a link.

How can I manually configure the forwarding. So that multicasts coming to eth0 are forwarded out eth1.

I was trying to make it work with the following command:
route add -net 224.0.0.0 netmask 240.0.0.0 eth0

But this seems only to be used for outgoing traffic.

I also tried out smcroute, but this daemon does not work on my Ubuntu.

Is it possible with iptables to do the forwarding? Or with this route add command?

Thx!!

Best Answer

A little late on this one, but here is a pretty solid guide http://troglobit.github.io/multicast-howto.html. At the end he mentions:

iptables -t mangle -A OUTPUT -d <group> -j TTL --ttl-set <num>

But my understanding is that you would want your network switches to handle the igmp querying/forwarding which your router would then use.

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