From owner-freebsd-stable@FreeBSD.ORG Thu Jan 18 23:51:29 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 CA6A616A415 for ; Thu, 18 Jan 2007 23:51:29 +0000 (UTC) (envelope-from kris@obsecurity.org) Received: from elvis.mu.org (elvis.mu.org [192.203.228.196]) by mx1.freebsd.org (Postfix) with ESMTP id B84B313C455 for ; Thu, 18 Jan 2007 23:51:29 +0000 (UTC) (envelope-from kris@obsecurity.org) Received: from obsecurity.dyndns.org (elvis.mu.org [192.203.228.196]) by elvis.mu.org (Postfix) with ESMTP id 912961A3C19; Thu, 18 Jan 2007 15:51:29 -0800 (PST) Received: by obsecurity.dyndns.org (Postfix, from userid 1000) id D7E1551482; Thu, 18 Jan 2007 18:51:25 -0500 (EST) Date: Thu, 18 Jan 2007 18:51:25 -0500 From: Kris Kennaway To: Roman Le Houelleur Message-ID: <20070118235125.GA80971@xor.obsecurity.org> References: <45AF8586.8080908@IPricot.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Nq2Wo0NMKNjxTN9z" Content-Disposition: inline In-Reply-To: <45AF8586.8080908@IPricot.com> User-Agent: Mutt/1.4.2.2i Cc: freebsd-stable@freebsd.org 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: Thu, 18 Jan 2007 23:51:29 -0000 --Nq2Wo0NMKNjxTN9z Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jan 18, 2007 at 03:34:46PM +0100, Roman Le Houelleur wrote: > Hi everyone, >=20 > 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. >=20 > First and easy one, tcpdump -v does not show checksum error > for UDP whereas it does for TCP (same w/ tcpdump -vvv). >=20 > 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 --Nq2Wo0NMKNjxTN9z Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (FreeBSD) iD8DBQFFsAf9Wry0BWjoQKURAgUiAKDpS88W53vTogqZzby1J+74iCEhkwCg5PkU VxmQnmZGoGeaEW7XrNnhgpg= =rCdw -----END PGP SIGNATURE----- --Nq2Wo0NMKNjxTN9z--