Re: IPv6 return path filter default active?
On Mon, 13 Aug 2012, Reinier Boon wrote:
> Thanks for your help and time!
>
> > First question: does the router A see the response coming from
> > router B and then drop it or does the router B drop the packet?
>
> Router A sees the packets coming in (I see them when I run tcpdump).
Well, it is time to investigate the less probable reasons...
Is the destination MAC address correct? Are you seeing the packets in the
tcpdump output even when the NIC is in non-promiscuous mode? Are
VLANs/802.1Q tagging involved? Inspect the tcpdump with wireshark or
something, and look for any weirdness, routing headers, etc. Check source
and destination addresses on all layers of the packet.
Are any ICMPv6 messages related to routing being received?
What happens when you set a trace on the packet?
ip6tables -t raw -I PREROUTING -j TRACE <rules to match what to
trace>
Make sure a logging backend, such as ip6t_LOG is loaded/built-in if the
trace doesn't show up.
> But router B knows where to send the packages: router A and B share
> routes via OSPF, and I see the packages coming in on router A.
> The problem must be in router A...
Manually check the kernel RIB of both routers for all the relevant
link-local and global addresses ("ip -6 route get").
--
"One disk to rule them all, One disk to find them. One disk to bring
them all and in the darkness grind them. In the Land of Redmond
where the shadows lie." -- The Silicon Valley Tarot
Henrique Holschuh
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