From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Tokarev Subject: Re: rare bad TCP checksum with 2.6.19? Date: Mon, 15 Jan 2007 17:25:37 +0300 Message-ID: <45AB8EE1.2010603@tls.msk.ru> References: <45AB82F1.9000409@tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 7bit Cc: Herbert Xu , netdev@vger.kernel.org Return-path: Received: from hobbit.corpit.ru ([81.13.94.6]:20839 "EHLO hobbit.corpit.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750729AbXAOOZl (ORCPT ); Mon, 15 Jan 2007 09:25:41 -0500 In-Reply-To: <45AB82F1.9000409@tls.msk.ru> To: unlisted-recipients:; (no To-header on input) Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Michael Tokarev wrote: [] > And another thing I noticed. Right now I'm experimenting with another > machine, running 2.6.17(.13) - it also shows similar behavior with bad > csums, but MUCH rarer than this 2.6.19. Like this: > > 16:29:32.490976 IP (tos 0x60, ttl 48, id 14110, offset 0, flags [DF], length: 80) > 69.42.67.34.2612 > 81.13.94.6.1234: . [bad tcp cksum f4b4 (->c1cc)!] ack 93407 win 9821 > This seems to be a tcpdump bug. At least the same packet(s), on another machine (in-between the two), with updated tcpdump, shows as having correct checksum. After updating tcpdump on this machine, I'm not seeing this 'sack bad cksum' stuff anymore. /mjt