Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030234AbVIBFpk (ORCPT ); Fri, 2 Sep 2005 01:45:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030202AbVIBFpj (ORCPT ); Fri, 2 Sep 2005 01:45:39 -0400 Received: from r-dd.iij4u.or.jp ([210.130.0.70]:5326 "EHLO r-dd.iij4u.or.jp") by vger.kernel.org with ESMTP id S1751105AbVIBFpj (ORCPT ); Fri, 2 Sep 2005 01:45:39 -0400 Date: Fri, 02 Sep 2005 14:45:37 +0900 (JST) Message-Id: <20050902.144537.35010282.Noritoshi@Demizu.ORG> From: Noritoshi Demizu To: Stephen Hemminger Cc: Ion Badulescu , 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 In-Reply-To: <20050901222032.5cc649c0@localhost.localdomain> References: <20050902.135138.38716488.Noritoshi@Demizu.ORG> <20050901222032.5cc649c0@localhost.localdomain> X-Mailer: Mew version 4.1 on Emacs 21 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1483 Lines: 33 > > 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 (DF) (259 ACKs are omitted here) > 11:34:54.611769 10.2.20.246.33060 > 10.2.224.182.8700: . ack 84454467 win 2355 (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 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/