[Twisted-Python] sniffing multicast traffic
ben at bbarker.co.uk
Wed Mar 10 06:50:55 EST 2010
Thanks Lars - yes, I am not adamant about using twisted, although it
seemed initially to be the best place to stary. I have also been
looking at the pcapy module, which I think may do what I want, but
also seems very low level.
On Wed, Mar 10, 2010 at 10:48 AM, Lars Ivar Igesund <larsivi at gmail.com> wrote:
> Hi Ben,
> my experience (not with Twisted, but with multicast), is that
> multicast often fail to be properly routed (this may be a restriction
> on OS, switch, etc). That you see the multicasts on using tshark is no
> indication on the routing working properly, as it will catch all
> information in promiscous mode, whether routed there or not.
> Two possible solutions (that may or may not be easy to in conjunction
> with Twisted) are:
> * Route the multicasts explicitly
> * Make the listening socket bind explicitly to the network interface
> where you expect/see the multicast. This is the solution I have used
> myself, but may require using low level socket functionality. Binding
> to localhost (all interfaces at once) or similar did not work for me.
> Best regards,
> Lars Ivar
> On Wed, Mar 10, 2010 at 11:35 AM, Ben Barker <ben at bbarker.co.uk> wrote:
>> Hello - I wonder if someone can help:
>> We have some status info being sent by various machines using
>> multicast addressed udp packets. I have been attempting to use twisted
>> to write a python script that will passively monitor on the relevant
>> port for any udp packets with the specified multicast address, which I
>> can then parse the payloads of as required.
>> I have been looking at the examples here:
>> But I seem to have trouble getting them to receive anything at all.
>> I have managed to use tshark to display the packets :
>> tshark -i eth0 -x -l -f udp
>> so I know the data is there (coming isn on address 126.96.36.199, port 901)
>> Any suggestions?
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