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

serg vasilyev sergv326 at
Wed Dec 15 00:13:25 UTC 2010

2009/12/9, Andriy Syrovenko <andriys at>:
> Hi,
> Well, turning off the transmit checksum offloading on the upstream
> interface solves the problem with IP checksums of IGMP report and
> leave messages always being 0. So after issuing the
> ifconfig re1 -txcsum
> command, the proxy successfully subscribes to receiving multicast
> streams, and I can see multicast UDP traffic coming in on the upstream
> interface. However there is another serious problem. Shortly alfter my
> router starts forwarding multicast traffic kernel crashes. The crash
> may happen either immediately when I press the play button in my IPTV
> player, or just after several channel switches. You can find crash
> reports in the attached files. They are almost identical, differing
> only in whether the pf module is loaded.
> The interesting part of the story is if I block incoming UDP multicast
> traffic using something like
> block in quick inet proto udp from any to
> in my pf.conf, system remains stable. But as soon as I comment the
> rule and reload pf, kernel crashes. I suspect the problem is not
> strictly related to the igmp processing, but to the multicast routing
> in general. Probably something wrong with thread synchronization. My
> system is a dual-core Intel Atom.
> Another interesting observation is when my BSD box is disconnected
> from the upstream router, I can see only IGMPv3 messages going out the
> upstream interface, even despite the fact that igmpproxy supports
> IGMPv2 only.
> br,
> Andrey
Does your system do any nat processing ?

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