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Date:      Wed, 10 Apr 2002 11:06:44 +0200
From:      Paulius Bulotas <paulius@kaktusas.org>
To:        freebsd-net@freebsd.org
Subject:   strange network conversation
Message-ID:  <20020410090644.GB8914@kaktusas.org>

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Hello list,

I'm seeing strange? networking behaviour with my FreeBSD server, and it
seems that this list is tne right to ask ;)
Suppose, there is outgoing connection for whom dynamic rule is created
(that's how I noticed it - ipfw logs denied packets). My 4.4-Release
FreeBSD is hostA, something on the next end is hostB - smtp server.
That's how the end of smtp session looks:

_Host    tcpflags   seq   nseq   ack    data_
hostA ( [PSH,ACK],  seq1, nseq1, ack1, "QUIT" )
hostA ( [FIN,ACK], nseq1,  --  , ack1 )
hostB ( [[ACK],     ack1,  --  , nseq1)
hostB ( [PSH,ACK],  ack1, nseq2, nseq1, "221 Bye")
hostA ( [RST],     nseq1,  --  ,  --  )
hostB ( [FIN,ACK], nseq2,  --  , nseq1)
hostB ( [ACK],     nseq2+1, -- , nseq1+1)
hostB ( [FIN,PSH,ACK], ack1, nseq2, nseq1+1)
...

I'm wondering, why FreeBSD sends RST so early and hostB tries to send
something back (and that didn't match dynamic rule, which is destroyed
upon RST (I suspect))?
Is it possible to change this? (so that conversation between hostA and
hostB ended normally)

TIA
Paulius

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