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From: Patrick McHardy <kaber@trash.net>
To: Daniel Drake <dsd@gentoo.org>
Cc: netfilter-devel@lists.netfilter.org, linux-kernel@vger.kernel.org
Subject: Re: 2.6.12 netfilter: local packets marked as invalid
Date: Fri, 08 Jul 2005 16:32:54 +0200	[thread overview]
Message-ID: <42CE8E96.1040905@trash.net> (raw)
In-Reply-To: <42CE86B5.2080705@gentoo.org>

Daniel Drake wrote:
> When retrying the telnet test, this appears in the logs:
> 
> Jul  8 14:53:04 dsd inv IN=lo OUT=
> MAC=00:00:00:00:00:00:00:00:00:00:00:00:08:00 SRC=127.0.0.1 DST=127.0.0.1
> LEN=40 TOS=0x10 PREC=0x00 TTL=64 ID=15 DF PROTO=TCP SPT=80 DPT=58950 WINDOW=0
> RES=0x00 ACK RST URGP=0
> 
> Does this mean that the kernel thinks its own ACK RST packet is invalid?

I think I know what happens. In 2.6.12 we started dropping the conntrack
reference when a packet leaves IP, so packets on loopback are tracked
twice (LOCAL_OUT/PRE_ROUTING). TCP connection tracking destroys a
conntrack entry when the only reply is an RST. So when the packet is
tracked for the second time in PRE_ROUTING, the conntrack entry can't
be found anymore and the packet is considered invalid.

You could confirm this theory by logging invalid packets in LOCAL_OUT
and in PRE_ROUTING - only PRE_ROUTING should trigger. I'm going to
think about a solution meanwhile.

Regards
Patrick

WARNING: multiple messages have this Message-ID (diff)
From: Patrick McHardy <kaber@trash.net>
To: Daniel Drake <dsd@gentoo.org>
Cc: linux-kernel@vger.kernel.org, netfilter-devel@lists.netfilter.org
Subject: Re: 2.6.12 netfilter: local packets marked as invalid
Date: Fri, 08 Jul 2005 16:32:54 +0200	[thread overview]
Message-ID: <42CE8E96.1040905@trash.net> (raw)
In-Reply-To: <42CE86B5.2080705@gentoo.org>

Daniel Drake wrote:
> When retrying the telnet test, this appears in the logs:
> 
> Jul  8 14:53:04 dsd inv IN=lo OUT=
> MAC=00:00:00:00:00:00:00:00:00:00:00:00:08:00 SRC=127.0.0.1 DST=127.0.0.1
> LEN=40 TOS=0x10 PREC=0x00 TTL=64 ID=15 DF PROTO=TCP SPT=80 DPT=58950 WINDOW=0
> RES=0x00 ACK RST URGP=0
> 
> Does this mean that the kernel thinks its own ACK RST packet is invalid?

I think I know what happens. In 2.6.12 we started dropping the conntrack
reference when a packet leaves IP, so packets on loopback are tracked
twice (LOCAL_OUT/PRE_ROUTING). TCP connection tracking destroys a
conntrack entry when the only reply is an RST. So when the packet is
tracked for the second time in PRE_ROUTING, the conntrack entry can't
be found anymore and the packet is considered invalid.

You could confirm this theory by logging invalid packets in LOCAL_OUT
and in PRE_ROUTING - only PRE_ROUTING should trigger. I'm going to
think about a solution meanwhile.

Regards
Patrick


  reply	other threads:[~2005-07-08 14:32 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-07-08 13:59 2.6.12 netfilter: local packets marked as invalid Daniel Drake
2005-07-08 14:32 ` Patrick McHardy [this message]
2005-07-08 14:32   ` Patrick McHardy
2005-07-08 16:12   ` Daniel Drake
2005-07-12 11:58     ` Patrick McHardy
2005-07-12 11:58       ` Patrick McHardy
2005-07-12 13:21       ` Daniel Drake
2005-07-12 18:58       ` David S. Miller
2005-07-12 19:19         ` Chris Wright
2005-07-12 22:55           ` Patrick McHardy
2005-07-12 22:55             ` Patrick McHardy
2005-07-13  0:16             ` Chris Wright

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