Well that's odd... I changed the interfaces over - used eth1 for the connection to the network I need to sniff...
and now /sbin/ip maddr tells me I have joined 224.0.0.4 on eth0 ! Whichever interface is live, the join seems to happen on the other :-p What could there be about my network config that is making this happen :-p On Wed, Mar 10, 2010 at 1:03 PM, Ben Barker <b...@bbarker.co.uk> 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 224.0.0.4, 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 224.0.0.4 > inet 224.0.0.251 > inet 224.0.0.1 > 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... > > > As I said, the code I am using is taken from the above link, but the > exact listing is given below: > > from twisted.internet.protocol import DatagramProtocol > from twisted.internet import reactor > from twisted.application.internet import MulticastServer > > class MulticastServerUDP(DatagramProtocol): > def startProtocol(self): > print 'Started Listening' > # Join a specific multicast group, which is the IP we will respond to > self.transport.joinGroup('224.0.0.4') > > def datagramReceived(self, datagram, address): > print "Server Received:" + repr(datagram) > > > reactor.listenMulticast(901, MulticastServerUDP()) > reactor.run() > > > >> _______________________________________________ >> Twisted-Python mailing list >> Twisted-Python@twistedmatrix.com >> http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python >> > _______________________________________________ Twisted-Python mailing list Twisted-Python@twistedmatrix.com http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
