Viewing multicast group membership?

[Bruce M Simpson]

Hi,

Pardon me if this is an FAQ or answered somewhere else.

I've had a quick skim through the man pages and the source, and can't
seem to find a means of listing which IPv4 multicast groups a host is
currently a member of.

The net.igmp.stats sysctl only seems to maintain general protocol level
statistics; it doesn't contain group information. This is the sysctl reported
by 'netstat -g'.

I guess I need to write some code to open /dev/kmem and walk ifmultihead.
Or does someone have a hack lying around for this I can clean up and commit?

BMS