From owner-freebsd-hackers@FreeBSD.ORG  Tue Jan  2 01:33:37 2007
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
X-Original-To: hackers@freebsd.org
Delivered-To: freebsd-hackers@FreeBSD.ORG
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id 4584116A407
	for <hackers@freebsd.org>; Tue,  2 Jan 2007 01:33:37 +0000 (UTC)
	(envelope-from david@madole.net)
Received: from d.omd3.com (mx1.omd3.com [69.90.174.41])
	by mx1.freebsd.org (Postfix) with ESMTP id 26CA513C44B
	for <hackers@freebsd.org>; Tue,  2 Jan 2007 01:33:36 +0000 (UTC)
	(envelope-from david@madole.net)
Received: from [66.212.193.19] (helo=david)
	by d.omd3.com with esmtpsa (TLSv1:RC4-MD5:128) (Exim 4.54)
	id 1H1YNY-0005NS-Fp; Mon, 01 Jan 2007 20:23:48 -0500
Date: Mon, 01 Jan 2007 20:21:00 -0500
From: "David S. Madole" <david@madole.net>
To: 'Steve Watt' <steve@Watt.COM>,
	"'hackers@freebsd.org'" <hackers@freebsd.org>
X-Priority: 3
Organization: Optimized Micro Devices
X-Mailer: Bynari Insight Connector 3.1.1-1128233
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: quoted-printable
Message-Id: <20070102013337.26CA513C44B@mx1.freebsd.org>
Cc: 
Subject: RE: Interesting TCP issue
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 02 Jan 2007 01:33:37 -0000

> From Steve Watt on Monday, January 01, 2007 4:37 PM
>=20
> # tcpdump -vv -s 1500 -i dc0 -X net 213.244.128.0/18
> tcpdump: lestening on dc0, link-type EN10MB (Ethernet), capture size 1500
> bytes
> 13:18:13.607493 IP (tos 0x20, ttl  58, id 12896, offset 0, flags [DF],
> proto: TCP (6), length: 74) share.skype.net.50406 > wattres.watt.com.smtp=
:
> P, cksum 0x9297 (correct), 4072464914:4072464936(22) ack 1248591103 win 4=
6
> <nop,nop,timestamp 2511885672 520058954>
>         0x0000:  4520 004a 3260 4000 3a06 c609 d5f4 aa50  E..J2`@.:......=
P
>         0x0010:  425d 8582 c4e6 0019 f2bc e212 4a6b fcff  B]..........Jk.=
.
>         0x0020:  8018 002e 9297 0000 0101 080a 95b8 5568  ..............U=
h
>         0x0030:  1eff 784a 4548 4c4f 2073 6861 7265 2e73  ..xJEHLO.share.=
s
>         0x0040:  6b79 7065 2e6e 6574 0d0a                 kype.net..
>=20
> Interesting.  I presume it has something to do with the
> idiotically small window the remote server is advertising.  So I
> set net.inet.tcp.minmss down to 46, and that resulted in a RST
> being spit back to skype's server when its retransmit happened.

Are you sure the window is really that small and that window scaling was no=
t negotiated at the start of the connection? The initial packets are not ca=
ptured here so I can't tell.

Is it possible to get a really complete capture of a session including the =
initial handshake?

David