kern/138666: [multicast] [panic] not working multicast through igmpproxy

[Andriy Syrovenko]

2009/12/8 Bruce Simpson <bms at incunabulum.net>:
> The only other thing I can think of is: is this an igmpproxy issue, ie. is
> the IGMP traffic which is causing problems, coming from igmpproxy itself?
That's possible.

> The kernel never generates IGMP control traffic related to routing. Any IGMP
> traffic generated by userland, generally uses the raw socket interface.
I don't yet understand all the mechanics behind the multicast routing. And
igmpproxy does seem to use raw sockets to send igmp packets. However
when I tried to do some investigations yesterday evening, I added a couple of
printf()s to igmp_v1v2_queue_report() in sys/netinet/igmp.c, and I saw their
output in dmesg while switching multicast groups.

> Userland could potentially also use pcap to inject directly to the link
> layer, and indeed, that might be a more desirable situation where the daemon
> is intended to run on interfaces w/o an IPv4 address. Of course, this
> entirely bypasses the host IP stack.
This does not seem to be the case with the igmpproxy.