[Twisted-Python] sniffing multicast traffic

Phil Mayers p.mayers at imperial.ac.uk
Wed Mar 10 08:18:04 EST 2010

On 10/03/10 13:03, Ben Barker wrote:
>>> But I seem to have trouble getting them to receive anything at all.
>> That's a little vague. Does "trouble" mean "it sometimes works" or
>> "never works"?
> Sorry - yes, it was very vague! Never works. If I run wiresahrk I can
> see udp packets addressed to, port 901, flying past, however
> when I run my python script it does not appear to ever receive
> anything.
> The scritp I am running is almost identical to an exampel I found here:
> http://code.activestate.com/recipes/425975-simple-udp-multicast-client-
> server-using-twisted/
>>> I have managed to use tshark to display the packets :
>>> tshark -i eth0  -x -l -f udp
>> Can you post a complete example that isn't working for you?
>> When your code is running, have a look "/sbin/ip maddr" to ensure the
>> group has been added to the socket listen filter
> eth1
> 	link  01:00:5e:00:00:04
> 	link  33:33:ff:7a:7e:4e
> 	link  01:00:5e:00:00:fb
> 	link  01:00:5e:00:00:01
> 	link  33:33:00:00:00:01
> 	inet
> 	inet
> 	inet
> 	inet6 ff02::1:ff7a:7e4e
> 	inet6 ff02::1
> That's interesting.... eth1 is the wrong interface! In fact, it isn't
> connected to anything at all. eth0 is the interface that should be
> being used. I will try to swap them around, but presumably this is
> something I can specify somwhere...

Hmm. What does "ip route" say? Do you have routed out of 
eth1 somehow?

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