From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754248AbYE1Mqg (ORCPT ); Wed, 28 May 2008 08:46:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752071AbYE1MqZ (ORCPT ); Wed, 28 May 2008 08:46:25 -0400 Received: from 1wt.eu ([62.212.114.60]:1296 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751855AbYE1MqY (ORCPT ); Wed, 28 May 2008 08:46:24 -0400 Date: Wed, 28 May 2008 14:45:53 +0200 From: Willy Tarreau To: Pascal Hambourg Cc: Matthias Cramer , James Chapman , Andrew Morton , linux-kernel , netdev@vger.kernel.org Subject: Re: Wired behaviour with IPv6 over PPP Message-ID: <20080528124553.GA3252@1wt.eu> References: <48341C0B.7010003@interway.ch> <20080522014959.0f6191aa.akpm@linux-foundation.org> <48354318.60202@katalix.com> <4835C40B.60603@interway.ch> <20080524042911.GE6749@1wt.eu> <483D2D11.9080803@plouf.fr.eu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <483D2D11.9080803@plouf.fr.eu.org> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Wed, May 28, 2008 at 11:59:45AM +0200, Pascal Hambourg wrote: > Hello all, > > Willy Tarreau a écrit/wrote : > >On Thu, May 22, 2008 at 09:05:47PM +0200, Matthias Cramer wrote: > > > >>James Chapman wrote: > >> > >>>Andrew Morton wrote: > >>> > >>>>On Wed, 21 May 2008 14:56:43 +0200 Matthias Cramer > >>>> wrote: > >>>> > >>>>>I have a very wired behaviour when doing IPv6 over PPPoE. > >>>>> > >>>>>The situation: > >>>>> > >>>>>A linux box connected to a DSL Modem, on the other side is a Cisco > >>>>>LNS which terminates the PPP session (actually L2TP). > >>>>>I have control over both ends. > >>>>> > >>>>>When I have net.ipv6.conf.all.forwarding set to 0 then the ppp > >>>>>Interface gets a IPv6 address from the Cisco via IP6CP. > >>>>>When I have net.ipv6.conf.all.forwarding set to 1 them the ppp > >>>>>Interface does not get an address, it has only a normal link local > >>>>>address. > > AFAIK IPV6CP/PPP only allows to negotiate link local addresses. right. > So I > guess the global address and default route is assigned by another > mechanism, maybe stateless autoconfiguration using router advertisement, > although I was not aware it could be used on a PPP link because of the > absence of MAC address. Enabling global forwarding > (net.ipv6.conf.all.forwarding=1) disables stateless autoconfiguration > (see ip-sysctl.txt in kernel documentation) on all interfaces. I believe > this is consistent with the observed behaviour. > > >>>>>When I start the ppp session with forwarding set to 0 I can ping out > >>>>>and there exists a default route to ppp0 , then I switch forwarding to > >>>>>1 > >>>>>the default route disappears and therefore routing does not work any > >>>>>longer. > > I have read reports about this. I guess the logic is that enabling > forwarding turns the box into a router, so the default route learned > from another router's advertisements by autoconfiguration should be > deleted. Even the autoconfigured global address will eventually expire. > > >Well, at least it has been working for years in kernel 2.4 for me with > >pppd 2.4.2b3 to 2.4.4 (I've not upgraded my firewall to 2.6 yet). So > >it has definitely been working at some point. > > What exactly has been working ? Sorry, I understood that IPv6 addresses got lost when IP forwarding was set to 1, which sounded strange to me. I've re-read the original mail more carefully and noticed that it was _autoconfiguration_ which does not work. For this, I don't know as I don't use it. My bad. > PS : Willy, do you plan to backport the security fix for the sit module > from 2.6.25.3 into 2.4 ? Yes, any security fix must be backported when appropriate. I just don't remember about this one, maybe I missed it. Care to send a pointer to the commit in 2.6 ? Thanks, Willy