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Re: weird IPv6 packet dropping with 6to4
I hope I am not raising too much of a zombie by reviving this thread,
but I finally have time to work on this problem again, which, alas,
has not gone away by its own volition.
Date: Sun, 6 Sep 2009 00:39:38 +0100
From: Matthias Scheler <tron%zhadum.org.uk@localhost>
So it looks like it is neither an MTU nor an MSS issues.
Does "tcpdump -i pflog0" report any drop packets?
Yes. I did a little more experimentation tonight, and observed a lot
of dropped packets on pflog, mostly SYN/ACK packets in IPv6 on the
stf0 interface. I couldn't figure out why they were not being passed
by the rule
pass quick on stf0 inet6,
so I tried preceding the `block log all' rule by
pass quick log all,
and testing again. And the same packets got dropped! However, if I
comment out `block log all', then the packets get through. I thought
that the `quick' keyword meant `don't look at the remaining rules', so
that putting `pass quick log all' before `block log all' would cause
every packet to be passed -- yet somehow, some packets are still being
blocked (and recorded to pflog as being blocked by rule 1, which is
the `block log all' rule). My only remaining guess is that pf's state
may be interfering with my tests, but perhaps there is something about
my setup which I just don't understand (about which see the message
all that has changed is my public IPv4 address).
Let me know if you'd like some packet dumps, or anything else I could
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