From owner-freebsd-stable@FreeBSD.ORG Fri Jan 19 10:06:42 2007 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id B916616A407 for ; Fri, 19 Jan 2007 10:06:42 +0000 (UTC) (envelope-from roman@IPricot.com) Received: from mail.i2e.fr (mail.i2e.fr [195.115.69.236]) by mx1.freebsd.org (Postfix) with ESMTP id 4BF4013C428 for ; Fri, 19 Jan 2007 10:06:42 +0000 (UTC) (envelope-from roman@IPricot.com) Received: from mail (localhost [127.0.0.1]) by mail (Postfix) with ESMTP id 77BB4BBA4; Fri, 19 Jan 2007 11:06:38 +0100 (CET) Received: from [192.168.1.221] (unknown [81.255.193.109]) by mail.i2e.fr (Postfix) with ESMTP id 8067DBBA0; Fri, 19 Jan 2007 11:06:37 +0100 (CET) Message-ID: <45B09856.8080600@IPricot.com> Date: Fri, 19 Jan 2007 11:07:18 +0100 From: Roman Le Houelleur User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.8.0.9) Gecko/20061229 SeaMonkey/1.0.7 MIME-Version: 1.0 To: freebsd-stable@freebsd.org References: <45AF8586.8080908@IPricot.com> <20070118235125.GA80971@xor.obsecurity.org> In-Reply-To: <20070118235125.GA80971@xor.obsecurity.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Anti-Virus: Kaspersky Anti-Virus for MailServers 5.5.10/RELEASE, bases: 28092006 #213749, status: clean Cc: Kris Kennaway Subject: Re: tcpdump, rl, sis, fxp and multicast problems X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Jan 2007 10:06:42 -0000 that's very clever indeed ! Well, I was not quite sure it was actually performing the TCO (not to say I feel stupid ...). not very important but wouldn't it be better to set the checksum to 0 instead of some arbitrary (?) and confusing value then ? thank you anyway, Roman. Kris Kennaway wrote: > On Thu, Jan 18, 2007 at 03:34:46PM +0100, Roman Le Houelleur wrote: >> Hi everyone, >> >> It's been about a year or so that I upgrade my box to RELENG_6 >> from time to time. I got some suprises this week, I've seen a >> few things that made me think of hardware problems but some are >> definitly soft. >> >> First and easy one, tcpdump -v does not show checksum error >> for UDP whereas it does for TCP (same w/ tcpdump -vvv). >> >> checksum : I have a double port fxp 82550 Pro/100 board which >> makes plenty of checksum errors (UDP & TCP), I suspect this >> is related to checksum offloading but am not sure. I strongly >> believe this card was working fine a few days/weeks ago. > > And a priori it still is: by definition, checksum offload means that > the OS does not compute the checksum for outgoing packets, so tcpdump > doesn't see a valid checksum either. Unless you have evidence (from > e.g. observation on another host) that the checksums are not being > computed correctly, this is not a bug. It is, however, a FAQ ;-) > > Kris