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Date: Thu, 10 Feb 2005 13:28:52 -0800
From: Kris Kennaway <kris@obsecurity.org>
To: Sam Jansen <sam@meta.net.nz>
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cc: freebsd-net@freebsd.org
Subject: Re: SACK problems
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On Fri, Feb 11, 2005 at 10:15:35AM +1300, Sam Jansen wrote:
> During some testing on an isolated network we have, I found some=20
> interesting behaviour from a FreeBSD 5.3 host using TCP SACK.
>=20
> I've detailed this problem fully at:
>=20
>    http://www.wand.net.nz/~stj2/nsc/emu_freebsd.html
>=20
> PCAP traces and some screenshots from tcptrace graphs can be found at=20
> the above link to show what is happening. It looks to me like SACK=20
> blocks are being incorrectly generated in this example. I can't think of=
=20
> any valid reason why a SACK block would SACK from below the current ACK=
=20
> value to above it (which is the problem here).
>=20
> Thoughts, anyone? Am I just wrong here and this is valid, expected=20
> behaviour?

A fix to the SACK code was committed yesterday, which may or may not
be relevant.

Kris

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