From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 6 Sep 2001 15:33:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 6 Sep 2001 15:33:17 -0400 Received: from spike.porcupine.org ([168.100.189.2]:44810 "EHLO spike.porcupine.org") by vger.kernel.org with ESMTP id ; Thu, 6 Sep 2001 15:33:05 -0400 Subject: Re: notion of a local address [was: Re: ioctl SIOCGIFNETMASK: ip alias bug 2.4.9 and 2.2.19] In-Reply-To: "from dean gaudet at Sep 6, 2001 12:15:56 pm" To: dean gaudet Date: Thu, 6 Sep 2001 15:33:24 -0400 (EDT) Cc: Wietse Venema , Andrey Savochkin , Matthias Andree , Andi Kleen , linux-kernel@vger.kernel.org X-Time-Zone: USA EST, 6 hours behind central European time X-Mailer: ELM [version 2.4ME+ PL82 (25)] MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII Message-Id: <20010906193324.51AA9BC06C@spike.porcupine.org> From: wietse@porcupine.org (Wietse Venema) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org dean gaudet: > On Thu, 6 Sep 2001, Wietse Venema wrote: > > > Andrey Savochkin: > > > > That is not practical. Surely there is an API to find out if an IP > > > > address connects to the machine itself. If every UNIX system on > > > > this planet can do it, then surely Linux can do it. > > > > > > Let me correct you: you need to recognize not addresses that result in > > > connecting to the _machine_ itself, but connecting to the same _MTA_. > > > > The SMTP RFC requires that user@[ip.address] is correctly recognized > > as a final destination. This requires that Linux provides the MTA > > with information about IP addresses that correspond with INADDR_ANY. > > > > I am susprised that it is not possible to ask such information up > > front (same with netmasks), and that an application has to actually > > query a complex oracle, again and again, for every IP address. > > how does your MTA figure out that it's behind a NAT? it doesn't matter > what unix it's running on, there's no standard way for it to know that an > address translation has occured before getting to its front-door. The MTA does not have to know. The DNS on the inside of the NAT gateway should list "inside" machines by their "inside" address. That eliminates a lot of other problems as well. Wietse