Problem in listening to multicast in multihomed Linux server

I am trying to write a multicast client on a machine with two NICs, and I can't make it work. I can see with a sniffer that once I start the program the NIC (eth4) start receiving the multicast datagrams: y.y.y.y. (some ip) -> z.z.z.z (multicast ip, not my eth4 NIC IP) UDP Source port: kkk (some other port) Destination port: xxx (multicast port)

However, I can't get those packets using my program (listening to port xxx on eth4).

I also added: route add 224.0.0.0 netmask 240.0.0.0 dev eth4

Searched the web for some examples/explanations, but it seems like I do what everybody else does. Any help will be appreciated. is there anything else to do with route/iptables?

Lior

Posted 2011-02-27T12:20:44.930

Reputation: 1

Question related to this was already moved to stack overflow, http://stackoverflow.com/questions/5132654/problem-in-listening-to-multicast-in-c-with-multiple-nics

– Olli – 2011-02-27T12:31:18.977

yeh, I want to make sure my Linux configuration is fine. thx. – Lior – 2011-02-27T12:55:18.793

as I said, tcpdump shows the packets received by multicast IP, not my eth4 NIC static IP. is that how should I see it? shouldn't tcpdump show the packets arriving to my NIC static ip? – Lior – 2011-02-27T12:54:33.673

Sorry, I missed that from your question. Yes, that's how it should work. You receive multicast packets to multicast IP, not to your own IP address. – Olli – 2011-02-27T13:04:19.900

Problem in listening to multicast in multihomed Linux server

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