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Ubuntu Networking :: Unable To Receive Multicast?


For the last couple of days, I've been unsuccesfully trying to receive multicast packets on Ubuntu Server 11.04, and seen some strange things along the way. The program i use to test this, is basically http://www.scribd.com/doc/38224328/mcreceive-c.Now the network has been configured to forward me the multicast packets, regardless of the joins. So tcpdump shows me:

Code:
15:16:11.308952 IP 10.164.130.2.61417 > 224.16.17.23.47806: UDP, length 1400
...

[code]....


View 2 Replies (Posted: June 23rd, 2011)

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Fedora Networking :: Unable To Receive Multicast Data
I have just set up an FC 13 box for a small network application. At the core, the application is supposed to receive some data over a multicast on my local network. However, for some reason, I am not being able to receive any multicast data on this machine. Other machines, on the same network (connected on the same layer 2 switch) are receiving the multicast just fine. I have tried the following things:

1. ensure that I am joining the multicast on the correct interface: the machine has only one ethernet card. Also, after starting my application, I use netstat -g to check for group membership. The multicast subscription shows up fine.

2. ensure there is no error in the program: the program works fine on my person linux machine

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4. no firewall/filtering settings on the layer2 switch

5. TTL setting on the broadcast: have tried changing it from 1 through 5 with no effect. Note that even if the broadcast is coming from the same machine, my machine does not pick it up while other machines on the network do so.

I suspect this has to do with some settings on the network card itself. Below is the output of /sbin/ifconfig on the card:

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Posted: 13th June 2010, 03:49 PM

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But when running on the Gumstix I can send udp multicast packets to Windows, but cannot receive them. (It works if I do point to point with a known IP port#, but not multicast.) I can run tcpdump on the Gumstix and see the packets, but they are not being received on my socket. Here's what tcpdump (running on the Gumstix) outputs when sending the same packet from different sources. Notice the IP header ID and flags (don't fragment) are different when coming from Windows.

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[Code]...

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