From owner-freebsd-stable@FreeBSD.ORG Wed Oct 24 16:24:33 2012 Return-Path: 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 8B4724FC; Wed, 24 Oct 2012 16:24:33 +0000 (UTC) (envelope-from h.schmalzbauer@omnilan.de) Received: from host.omnilan.net (s1.omnilan.net [62.245.232.135]) by mx1.freebsd.org (Postfix) with ESMTP id D96A08FC0A; Wed, 24 Oct 2012 16:24:32 +0000 (UTC) Received: from titan.inop.wdn.omnilan.net (titan.inop.wdn.omnilan.net [172.21.3.1]) (authenticated bits=0) by host.omnilan.net (8.13.8/8.13.8) with ESMTP id q9OGPrSm072583 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 24 Oct 2012 18:25:53 +0200 (CEST) (envelope-from h.schmalzbauer@omnilan.de) Message-ID: <5088163E.2090506@omnilan.de> Date: Wed, 24 Oct 2012 18:24:30 +0200 From: Harald Schmalzbauer Organization: OmniLAN User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; de-DE; rv:1.9.2.8) Gecko/20100906 Lightning/1.0b2 Thunderbird/3.1.2 MIME-Version: 1.0 To: Jeremy Chadwick Subject: Re: every 2nd echo-request malformed when ping -s >4067 References: <20121024154017.GA3167@icarus.home.lan> In-Reply-To: <20121024154017.GA3167@icarus.home.lan> X-Enigmail-Version: 1.1.2 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig3B546E6D0DDE8702202A5B74" Cc: adrian@freebsd.org, freebsd-stable@freebsd.org X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 24 Oct 2012 16:24:33 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig3B546E6D0DDE8702202A5B74 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable schrieb Jeremy Chadwick am 24.10.2012 17:40 (localtime): > (Please keep me CC'd as I'm not subscribed) > > Regarding: > > http://lists.freebsd.org/pipermail/freebsd-stable/2012-October/070239.h= tml > > tcpdump -x is not helpful here. tcpdump -xx would be. > > tcpdump -x dumps the *payload* portion of the packet, while -xx dumps > everything (all headers/protocol data included). > > The reason I say -xx would be helpful is because of this: > >> 2nd: 12:21:10.052891 IP 10.5.49.126 > 10.5.49.65: icmp >> 0x0000: 4500 1000 0f2d 0040 4001 e4c7 0a05 317e > The ICMP code/type and related header data is not being decoded > correctly, or is being *encoded* incorrectly. I can't tell because all= > that's shown there is the payload!=20 Hmm, if I understand things right, there's only the link-level-header missing, meaning the ethernet adresses. Not the IP-header. Verified that: 1st: 16:03:08.963292 IP 10.5.49.126 > 10.5.49.65: ICMP echo request, id 30477, seq 0, length 4076 000c 29f1 8424 90e2 ba18 f885 0800 2nd: 16:03:09.968454 IP 10.5.49.126 > 10.5.49.65: icmp 000c 29f1 8424 90e2 ba18 f885 0800 Since the link-level-header is identical, the problem must be later and the former dump should be valid. That's easily reproducable everywhere, since lo0 has mtu 16384, so just ' ping -D -s 4068 127.0.0.1 '. Thanks, -Harry --------------enig3B546E6D0DDE8702202A5B74 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) iEYEARECAAYFAlCIFj4ACgkQLDqVQ9VXb8hWnwCfcfDpTztBpewIDY3io5zTsidS q/8AoJCYPjPCnDPmThmjfLYZKa+/7f7r =aPBZ -----END PGP SIGNATURE----- --------------enig3B546E6D0DDE8702202A5B74--