IPv6 multicast in 2.4.25 broken?

From: Ignacy Gawedzki
Date: Wed Mar 24 2004 - 13:53:55 EST


It seems that simple multicast support in IPv6 has ceased working
starting at kernel version 2.4.25-pre4. More specifically, receiving
multicast packets (those with destination address ff05::1 or ff02::1) is
broken (read: sending is okay). The same binary run on kernels 2.4.24
and earlier works with no problem.

I tried as many combinations of USAGI patches and kernel versions as I
could, but cannot figure the exact source of the problem. I did not
inspect the diffs with enough attention, though.

Another funny thing is that the changelog for version 2.4.25-pre4
doesn't mention any change to IPv6 code.

Did anyone have similar experience and or suggestions?

I have not subscribed to the linux-kernel list, because of its high
traffic, so please CC me the replies.



PS: The detailed way in which I prepare the socket is the following:

Open a UDP socket in IPv6 protocol family.

Bind it to network interface using SO_BINDTODEVICE.

Set the multicast network interface using IPV6_MULTICAST_IF.

Bind it to the network interface's address (which is set manually to

Set the multicast hops with IPV6_MULTICAST_HOPS to 1.

Set the multicast membership to ff02::1 (or ff05::1) using

Unset the multicast loop using IPV6_MULTICAST_LOOP.

Note: the same socket is used to send and receive multicast packets.

To err is human, to moo bovine.
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