From: Noritoshi Demizu <demizu@dd.iij4u.or.jp>
To: Stephen Hemminger <shemminger@osdl.org>
Cc: Ion Badulescu <lists@limebrokerage.com>,
linux-kernel@vger.kernel.org, linux-net@vger.kernel.org
Subject: Re: Possible BUG in IPv4 TCP window handling, all recent 2.4.x/2.6.x kernels
Date: Fri, 02 Sep 2005 14:45:37 +0900 (JST) [thread overview]
Message-ID: <20050902.144537.35010282.Noritoshi@Demizu.ORG> (raw)
In-Reply-To: <20050901222032.5cc649c0@localhost.localdomain>
> > Since the TCP Window Scale options are exchanged,
> > the window size field contains shifted value except SYNs.
>
> Be careful, tcpdump may be tracking the window scale and reporting
> scaled values. Seems unlikely since with a window scale of 2, and odd
> window size would be impossible.
I am sorry if tcpdump tracks the window scale option. But I think it
is unlikely, because there are odd window sizes, as you pointed out.
By the way, if tcpdump does not track the window scale option, the right
edge (ack + real win) does not change between the following two ACKs.
> 11:34:54.337167 10.2.20.246.33060 > 10.2.224.182.8700: . ack 84402527 win 15340 <nop,nop,timestamp 226080473 99717814> (DF)
(259 ACKs are omitted here)
> 11:34:54.611769 10.2.20.246.33060 > 10.2.224.182.8700: . ack 84454467 win 2355 <nop,nop,timestamp 226080721 99717841> (DF)
The first line is the 37th ACK and the second line is the 295th ACK.
ACK#37: ack=84402527 win=15340 right_edge=84463887 (= ack + win * 4)
ACK#295: ack=84454467 win=2355 right_edge=84463887 (= ack + win * 4)
And all ACKs later than ACK#295 has win=2355 (2355*4=9420).
This may be a hint. But, sorry, I do not know the internal of Linux TCP.
Regards,
Noritoshi Demizu
next prev parent reply other threads:[~2005-09-02 5:45 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-01 22:30 Ion Badulescu
2005-09-01 22:43 ` David S. Miller
2005-09-01 22:49 ` Jesper Juhl
2005-09-01 22:53 ` David S. Miller
2005-09-01 22:53 ` Ion Badulescu
2005-09-01 23:37 ` Jesper Juhl
2005-09-02 2:51 ` John Heffner
2005-09-02 6:28 ` David S. Miller
2005-09-02 14:05 ` lists
2005-09-02 14:10 ` John Heffner
2005-09-02 14:33 ` lists
2005-09-02 14:48 ` John Heffner
2005-09-02 15:43 ` Ion Badulescu
2005-09-02 13:02 ` Guillaume Autran
2005-09-02 13:48 ` Ion Badulescu
2005-09-02 13:52 ` Alexey Kuznetsov
2005-09-02 14:11 ` John Heffner
2005-09-02 13:48 ` Alexey Kuznetsov
2005-09-02 14:16 ` John Heffner
2005-09-02 15:11 ` Alexey Kuznetsov
2005-09-02 18:36 ` Alexey Kuznetsov
2005-09-02 20:57 ` Ion Badulescu
2005-09-02 21:18 ` Alexey Kuznetsov
2005-09-02 23:09 ` Ion Badulescu
2005-09-28 16:31 ` Ion Badulescu
2005-09-29 15:17 ` Alexey Kuznetsov
2005-09-29 15:34 ` Guillaume Autran
2005-09-29 16:04 ` John Heffner
2005-09-29 18:16 ` David S. Miller
2005-09-30 0:29 ` David S. Miller
2005-09-02 4:51 ` Noritoshi Demizu
2005-09-02 5:20 ` Stephen Hemminger
2005-09-02 5:45 ` Noritoshi Demizu [this message]
2005-09-02 6:11 ` Noritoshi Demizu
2005-09-02 12:11 ` Ion Badulescu
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