Receiving IGMP packets with raw socket

[avijit at cs.ucsb.edu]

I am developing an application for multicast detection on Fedora core. As
part of it I have to inspect IGMP packets arriving from routers (e.g.
Membership Query). I am using raw socket with IPPROTO_IGMP to send and
receive IGMP packets. Using ethereal I can see the IGMP packets going out
and coming in to the host. However, incoming IGMP packets never arrive to
my user level process - socket 'receivefrom' simply does not get them. I am
not sure whether I have to set any socket option or ioctl to receive IGMP
packets at user process level. I will appreciate any help. I can post my
code if required. Also please let me know if I should post it to some other
mailing list.

Thanks.
Avijit