From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755057AbXGBS3G (ORCPT ); Mon, 2 Jul 2007 14:29:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752606AbXGBS2y (ORCPT ); Mon, 2 Jul 2007 14:28:54 -0400 Received: from mail.ipom.com ([69.73.131.218]:60090 "EHLO mail.ipom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751348AbXGBS2y (ORCPT ); Mon, 2 Jul 2007 14:28:54 -0400 Date: Mon, 2 Jul 2007 11:28:50 -0700 From: Phil Dibowitz To: Andreas Steinmetz Cc: Jan Engelhardt , netfilter-devel@lists.netfilter.org, Linux Kernel Mailinglist Subject: Re: mss to pmtu clamping partially broken? Message-ID: <20070702182850.GB14507@ipom.com> References: <4684E853.20900@domdv.de> <4689300C.9050802@domdv.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="i9LlY+UWpKt15+FH" Content-Disposition: inline In-Reply-To: <4689300C.9050802@domdv.de> User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --i9LlY+UWpKt15+FH Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jul 02, 2007 at 07:04:12PM +0200, Andreas Steinmetz wrote: > Jan Engelhardt wrote: > > Do you really need clamping? It's a hack, since TCP should do MSS negot= iation > > itself. (Of course it may happen that some routers are broken.) But usu= ally not > > for incoming packets. >=20 > You never know when you hit ICMP blackholes, broken routers and other > evil things. Better safe than sorry so clamping is the way to go for me. I encourage you to report PMTUD Blackholes to the MSS Initiative at http://www.phildev.net/mss/ We'll notify them, and if we can't get them to fix it, blacklist them. We h= ave more fixed sites than blacklisted sites, so it's at least somewhat successf= ul. --=20 Phil Dibowitz phil@ipom.com Open Source software and tech docs Insanity Palace of Metallica http://www.phildev.net/ http://www.ipom.com/ "Never write it in C if you can do it in 'awk'; Never do it in 'awk' if 'sed' can handle it; Never use 'sed' when 'tr' can do the job; Never invoke 'tr' when 'cat' is sufficient; Avoid using 'cat' whenever possible" -- Taylor's Laws of Programming --i9LlY+UWpKt15+FH Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFGiUPiN5XoxaHnMrsRApbyAJ9azJ3vpKJCzJZLxuBYycYa+WxrMQCgpLTz HGM+fnK1LfH8CmxIk5Nm8fU= =4LAJ -----END PGP SIGNATURE----- --i9LlY+UWpKt15+FH--