Multicast routing, what do I need to do?

I read about allowing traffic to or from 224.0.0.0/4 (can't remember) in the firewall section to make multicast routable across different subnets, but I'm not sure how it's done.

The two subnets in question are LAN1 (192.168.1.0/24) and LAN2 (192.168.10.0/24), which reside in the same firewall zone, how do I set in the firewall section to allow devices in either subnet to discover services in the other? Thank you.

Have a look here.

2 Likes

Thank you trendy for pointing me the right direction, I'll try the suggested solution and report back.

I guess there's some limitation with the iptables version 1.8.3 that comes with the Openwrt, while excuting

"iptables -t mangle -A PREROUTING -i br-lan -d 224.0.0.0/4 -j TTL --ttl-inc 1
iptables -t mangle -A PREROUTING -i br-lan2 -d 224.0.0.0/4 -j TTL --ttl-inc 1",

I got the message
iptables v1.8.3 (legacy): unknown option "--ttl-inc"

any suggestions? Thank you!

opkg list-installed | grep iptables ?

the output is
iptables - 1.8.3-1

You need also ipopt

Thank you! I just did it.

From my test, even without the TTL hack, I can discover DLNA across subnets, and now with the help of it, I'm still not seeing chromecast targets on the other side, do you have experiences with the chromecast "issue"?

I don't have experience with Chromecast, but as with any problem, you'll have to troubleshoot it.
First of all verify that the rules you added have some hits (`iptables-save -c | grep TTL)
Verify with tcpdump that the packets received are relayed to the other interface.

1 Like

I appreciate the help trendy, many times you've given me the right answers, I'll dig deeper.

1 Like