From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: NAT stops forwarding ACKs after PMTU discovery Date: Mon, 19 Aug 2013 08:32:05 -0700 Message-ID: <1376926325.4226.64.camel@edumazet-glaptop> References: <521061B4.1030508@fatooh.org> <1376839467.21329.36.camel@edumazet-glaptop> <1376870425.4226.25.camel@edumazet-glaptop> <1376870592.4226.27.camel@edumazet-glaptop> <5211DAA6.1070302@fatooh.org> <20130819123314.GC3583@cpaasch-mac> <1376918657.4226.59.camel@edumazet-glaptop> <20130819134919.GF3583@cpaasch-mac> <1376920685.4226.61.camel@edumazet-glaptop> <20130819143509.GA31320@linuxace.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Christoph Paasch , Corey Hickey , Jozsef Kadlecsik , Linux Netdev List , netfilter-devel@vger.kernel.org To: Phil Oester Return-path: Received: from mail-pa0-f48.google.com ([209.85.220.48]:33454 "EHLO mail-pa0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750807Ab3HSPcQ (ORCPT ); Mon, 19 Aug 2013 11:32:16 -0400 In-Reply-To: <20130819143509.GA31320@linuxace.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2013-08-19 at 07:35 -0700, Phil Oester wrote: > On Mon, Aug 19, 2013 at 06:58:05AM -0700, Eric Dumazet wrote: > > Yeah, but here, this is conntrack who is blocking the thing. > > > > TCP receiver has no chance to 'fix' it. > > > > See conntrack is one of those buggy middle box as well. > > > > So if you want to properly handle this mess, you'll also have to fix > > conntrack. > > Better to fix the box which is randomizing the acks and ignoring > the SACKs. Usually these are older Cisco PIX/ASA devices which just > need a code upgrade. Having a patch to relax things could be evaluated, if not adding new problems ( http://en.wikipedia.org/wiki/Robustness_principle )