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Date: Mon, 10 Dec 2001 20:16:07 +0200
From: Mika Liljeberg <Mika.Liljeberg@welho.com>
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To: kuznet@ms2.inr.ac.ru, davem@redhat.com
CC: linux-kernel@vger.kernel.org
Subject: TCP LAST-ACK state broken in 2.4.17-pre2
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Hi,

I came across the following behavior (sorry, no tcpdump but this should
be easy to reproduce with the right tools):

hostA                 hostB
  --------FIN----------->
  <-----data+FIN---------
  --------ACK-------X       (packet lost)
  <-----data+FIN---------   (retransmit)
  <-----data+FIN---------   (retransmit)
  <-----data+FIN---------   (retransmit)
          ....
  <-----data+FIN---------   (retransmit)
  --------RST----------->

HostA is running Linux 2.4.17-pre2. HostB is running Symbian OS. All the
sequence numbers pan out.

Either LAST-ACK is completely broken or Linux just cannot handle a
FIN-ACK that is piggybacked on a data segment, when received in LAST-ACK
state. It should be acked as an out-of-window segment, as usual.
Finally, the LAST-ACK state times out and Linux responds to the FIN
segment with an RST.

Cheers,

	MikaL
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