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 13:05:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 6 Sep 2001 13:05:26 -0400 Received: from shed.alex.org.uk ([195.224.53.219]:43697 "HELO shed.alex.org.uk") by vger.kernel.org with SMTP id ; Thu, 6 Sep 2001 13:05:12 -0400 Date: Thu, 06 Sep 2001 18:05:30 +0100 From: Alex Bligh - linux-kernel Reply-To: Alex Bligh - linux-kernel To: Andrey Savochkin , Matthias Andree Cc: Wietse Venema , Andi Kleen , linux-kernel@vger.kernel.org, Alex Bligh - linux-kernel Subject: Re: notion of a local address [was: Re: ioctl SIOCGIFNETMASK: ip alias bug 2.4.9 and 2.2.19] Message-ID: <605440607.999799530@[10.132.112.53]> In-Reply-To: <20010906203854.A23109@castle.nmd.msu.ru> In-Reply-To: <20010906203854.A23109@castle.nmd.msu.ru> X-Mailer: Mulberry/2.1.0 (Win32) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrey, --On Thursday, September 06, 2001 8:38 PM +0400 Andrey Savochkin wrote: > Hell, how else could you define the notion of a local address as not the > address which responds to pings without external network, the address for > which So the remote end of a looped /30 serial line is now a local address? Can you bind() to 127.0.0.2? In any case, all you've found is a peculiarity of the loopback driver. So send a patch. The read RFC1122. (hosts & routers requirements). Not only does this define local address, but specifically writes: 3.3.4.2 Multihoming Requirements The following general rules apply to the selection of an IP source address for sending a datagram from a multihomed host. (1) If the datagram is sent in response to a received datagram, the source address for the response SHOULD be the specific-destination address of the request. See Sections 4.1.3.5 and 4.2.3.7 and the "General Issues" section of [INTRO:1] for more specific requirements on higher layers. Otherwise, a source address must be selected. (2) An application MUST be able to explicitly specify the source address for initiating a connection or a request. How can (2) be usefully true if the application cannot determine what the list of valid local addresses are? Or is your argument that all such addresses should be configured manually, rather than by the application? Which would not only be a rather odd point of view, but makes implementing things like BGP, which depends on being able to get the outbound interface address used for a session up to the higher layers, rather hard. -- Alex Bligh