Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263273AbTETAXh (ORCPT ); Mon, 19 May 2003 20:23:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263276AbTETAXh (ORCPT ); Mon, 19 May 2003 20:23:37 -0400 Received: from zcars04f.nortelnetworks.com ([47.129.242.57]:34197 "EHLO zcars04f.nortelnetworks.com") by vger.kernel.org with ESMTP id S263273AbTETAXe (ORCPT ); Mon, 19 May 2003 20:23:34 -0400 Message-ID: <3EC97889.6040509@nortelnetworks.com> Date: Mon, 19 May 2003 20:36:25 -0400 X-Sybari-Space: 00000000 00000000 00000000 From: Chris Friesen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.8) Gecko/20020204 X-Accept-Language: en-us MIME-Version: 1.0 To: David Ashley Cc: linux-kernel@vger.kernel.org Subject: Re: Problem in ARP 2.4.20 kernel References: <200305162202.h4GM2LGN024925@xdr.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2428 Lines: 64 David Ashley wrote: > The problem I ran into was the kernel's handling of ARP requests. What linux > does is each interface receives the arp request, and every single one > answers the request. So it becomes a race condition which response gets to > the client, and the client will have usually an incorrect mac address/ip > address arp entry. This was hashed through on the list about a year back. You might try googling next time... This is actually standards compliant behaviour, as silly as it sounds. However, if you want stricter arp behaviour, and are using source-based routing, the following will fix it. echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter Here is an example setup on 2.4.18: # ip add 1: lo: mtu 16436 qdisc noqueue link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 brd 127.255.255.255 scope host lo 2: eth0: mtu 1500 qdisc pfifo_fast qlen 100 link/ether 00:30:65:bf:46:ba brd ff:ff:ff:ff:ff:ff inet 47.129.82.58/24 brd 47.129.82.255 scope global eth0 3: eth1: mtu 1500 qdisc pfifo_fast qlen 100 link/ether 00:50:ff:90:04:44 brd ff:ff:ff:ff:ff:ff inet 47.129.82.107/24 brd 47.129.82.255 scope global eth1 # ip ru 0: from all lookup local 32764: from 47.129.82.107 lookup 101 32765: from 47.129.82.58 lookup 100 32766: from all lookup main 32767: from all lookup 253 # ip ro 47.129.82.0/24 dev eth0 proto kernel scope link src 47.129.82.58 47.129.82.0/24 dev eth1 proto kernel scope link src 47.129.82.107 127.0.0.0/8 dev lo scope link default via 47.129.82.1 dev eth0 # ip ro li table 100 47.129.82.0/24 dev eth0 scope link default via 47.129.82.1 dev eth0 # ip ro li table 101 47.129.82.0/24 dev eth1 scope link default via 47.129.82.1 dev eth1 With this setup, arp requests for 47.129.82.58 will only be answered by eth0, and similarly for 47.129.82.107 and eth1. Chris -- Chris Friesen | MailStop: 043/33/F10 Nortel Networks | work: (613) 765-0557 3500 Carling Avenue | fax: (613) 765-2986 Nepean, ON K2H 8E9 Canada | email: cfriesen@nortelnetworks.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/