From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261296AbTDOMAT (for ); Tue, 15 Apr 2003 08:00:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261349AbTDOMAS (for ); Tue, 15 Apr 2003 08:00:18 -0400 Received: from chaos.analogic.com ([204.178.40.224]:2944 "EHLO chaos.analogic.com") by vger.kernel.org with ESMTP id S261296AbTDOL7C (for ); Tue, 15 Apr 2003 07:59:02 -0400 Date: Tue, 15 Apr 2003 08:10:59 -0400 (EDT) From: "Richard B. Johnson" X-X-Sender: root@chaos Reply-To: root@chaos.analogic.com To: Stephan von Krawczynski cc: linux-kernel Subject: Re: How to configure an ethernet dev as PtP ? In-Reply-To: <20030415102109.4802ddd0.skraw@ithnet.com> Message-ID: References: <20030415102109.4802ddd0.skraw@ithnet.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 15 Apr 2003, Stephan von Krawczynski wrote: > Hello all, > > I tried to configure an ethernet device as a pointopoint link recently, just to > find out that this does not work as one would expect via: > > ifconfig eth0 192.168.1.1 pointopoint 192.168.5.1 up > > I tried on kernel 2.4.21-pre6 and 2.2.19 (just to name two), both the same. It > comes up as: > > eth0 Link encap:Ethernet HWaddr 00:04:76:F7:E9:17 > inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0 > UP BROADCAST MULTICAST MTU:1500 Metric:1 > > I do not understand why this does not work out just like another ptp-interface > like isdn: > > isdn0 Link encap:Ethernet HWaddr FC:FC:00:00:00:00 > inet addr:192.168.1.1 P-t-P:192.168.5.1 Mask:255.255.255.255 > UP POINTOPOINT RUNNING NOARP MTU:1500 Metric:1 > > Is there anything I mis-understood or a good reason for not being able to make > eth pointopoint? > > I have the feeling this question is pretty brain-dead, but anyway, maybe some > kind soul can drop a few words ... > -- > Regards, > Stephan Because ethernet is not a point-to-point interface. At the hardware level, ethernet talks from one hardware address to another hardware address, i.e., the IEEE station address. You need ARP to find out what that address is so you can't "get there from here." But, you can do essentially the same thing, you set up a host route on that interface. Use a 'private' network address... On one host: ifconfig eth1 10.0.0.1 netmask 255.255.255.0 broadcast 10.0.0.255 route add -host my-router-ip-address dev eth1 On the other host: ifconfig eth1 10.0.0.2 netmask 255.255.255.0 broadcast 10.0.0.255 route add -host my-client-ip-address dev eth1 Cheers, Dick Johnson Penguin : Linux version 2.4.20 on an i686 machine (797.90 BogoMips). Why is the government concerned about the lunatic fringe? Think about it.