From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261238AbTHSTPs (ORCPT ); Tue, 19 Aug 2003 15:15:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261226AbTHSTPR (ORCPT ); Tue, 19 Aug 2003 15:15:17 -0400 Received: from relay.pair.com ([209.68.1.20]:16391 "HELO relay.pair.com") by vger.kernel.org with SMTP id S261337AbTHSTMq (ORCPT ); Tue, 19 Aug 2003 15:12:46 -0400 X-pair-Authenticated: 68.40.145.213 Subject: Re: [2.4 PATCH] bugfix: ARP respond on all devices From: Daniel Gryniewicz To: "David S. Miller" Cc: alan@lxorguk.ukuu.org.uk, richard@aspectgroup.co.uk, skraw@ithnet.com, willy@w.ods.org, carlosev@newipnet.com, lamont@scriptkiddie.org, davidsen@tmr.com, bloemsaa@xs4all.nl, marcelo@conectiva.com.br, netdev@oss.sgi.com, linux-net@vger.kernel.org, layes@loran.com, torvalds@osdl.org, linux-kernel@vger.kernel.org In-Reply-To: <20030819112912.359eaea6.davem@redhat.com> References: <353568DCBAE06148B70767C1B1A93E625EAB57@post.pc.aspectgroup.co.uk> <1061296544.30566.8.camel@dhcp23.swansea.linux.org.uk> <1061317825.3744.7.camel@athena.fprintf.net> <20030819112912.359eaea6.davem@redhat.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Message-Id: <1061320363.3744.14.camel@athena.fprintf.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.3 Date: 19 Aug 2003 15:12:43 -0400 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I realize that, but is that a reason to keep linux from working with these? (And it's not just cisco, all the *BSDs (and therefore anything that took the BSD stack such as MS) work this way too.) As nearly as I can tell, there's no way to make linux work with these, and the situation I gave is one where linux could easily get it right, and isn't. Saying "They're broken. Tough." is not really helpful. At least can we get a "work with broken other systems in certain circumstances" switch somewhere? (Funny you should mention Cisco, as we write routing software and must interoperate with Cisco. What Cisco says *does* go in the routing community, if you wish your product to be used. Currently, when our customers come to us, we have to say "Either don't use Linux or run 2.2 with the arp fix patch.") Daniel On Tue, 2003-08-19 at 14:29, David S. Miller wrote: > On 19 Aug 2003 14:30:26 -0400 > Daniel Gryniewicz wrote: > > > If you are not on a shared lan, then it will *ONLY* work if linux is > > on the other end. No other system will work. > > And these other systems are broken. (actually, older Cisco equipment > correctly responds to the ARP regardless of source IP) > > Just because some Cisco engineer says that it is correct doesn't > make it is. > > Consider the situation logically. When you're replying to an > ARP, _HOW_ do you know what IP addresses are assigned to _MY_ > outgoing interfaces and _HOW_ do you know what subnets _EXIST_ > on the LAN? > > The answer to both is, you'd don't know these things _EVEN_ if > you are a router/gateway. > > Therefore there is no valid reason not to respond to an ARP using one > source address as opposed to another. -- Daniel Gryniewicz