Re: IGMP packets?

From: FoObArf00
Date: Wed Dec 08 2004 - 16:00:05 EST


I have 3 machines. A (eth0) is connected to B (eth1) with a cross over cable and B (eth0) and C (eth0) are on a switch. I want to forward the igmp queries and reports that A (eth1) generates when joining/leaving a multicast group on B (eth1) from B(eth0) to C (eth0). I put the code to do this on different places such as ip_rcv, ip_route_input, etc and no luck. The weird thing is that it works when I do a tcpdump on B's eth1.

A-(eth0)----(eth1)-B-(eth0)----(eth0)-C

Thanks.

Chris Wright <chrisw@xxxxxxxx> wrote:

>* FoObArf00@xxxxxxxxxxxx (FoObArf00@xxxxxxxxxxxx) wrote:
>> I have been trying to analyze igmp packets (queries, reports) with
>> ttl of 1 ,of course, in the kernel and ran into a weird situation.
>> Only when an interface is in promiscuous mode (i.e. tcpdump), the igmp
>> packets get to ip_rcv on ip_input.c. I was wondering if someone can
>> point in the right direction on how/where to get the these packets when
>> not doing a tcpdump. Thanks
>
>Could you be more specific? Which machines are involved (e.g. IIRC the
>igmp report is not looped back locally). What do you mean by analyze in
>the kernel?
>
>thanks,
>-chris
>

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