Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 16 Apr 2001 17:27:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 16 Apr 2001 17:27:00 -0400 Received: from mailhost3.lanl.gov ([128.165.3.9]:24175 "EHLO mailhost3.lanl.gov") by vger.kernel.org with ESMTP id ; Mon, 16 Apr 2001 17:26:51 -0400 Message-ID: <3ADB637B.13E4F1AD@lanl.gov> Date: Mon, 16 Apr 2001 15:26:19 -0600 From: Eric Weigle Organization: CCS-1 RADIANT team X-Mailer: Mozilla 4.7 [en] (X11; U; Linux 2.2.18 i686) X-Accept-Language: en, es-ES, ex-MX, fr-FR, fr-CA MIME-Version: 1.0 To: Sampsa Ranta , linux-net@vger.kernel.org, linux-kernel@vger.kernel.org, zebra@zebra.org Subject: Re: ARP responses broken! Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello- This is a known 'feature' of the Linux kernel, and can help with load sharing and fault tolerance. However, it can also cause problems (such as when one nic in a multi-nic machine fails and you don't know right away). There are three 'solutions' I know of: * In recent 2.2 kernels, it was possible to fix this by doing the following as root: # Start the hiding interface functionality echo 1 > /proc/sys/net/ipv4/conf/all/hidden # Hide all addresses for this interface echo 1 > /proc/sys/net/ipv4/conf//hidden but 2.4 doesn't have that option, for technical reasons. * Use 'ifconfig -arp ...' to force an interface not to respond to ARP requests. Hosts which want to send to that interface may need to manually add the proper mac address to their ARP tables with 'arp -s'. * Use a packet filtering tool (iptables arp filter module, for example) and just filter the ARP requests and ARP replies so that only the proper set get through, i.e. when an arp request for the mac address of an interface arrives, filter out arp replies from all the other interfaces. There have been a few threads on this on the linux-kernel mailing list. Search your favorite archive for them. -Eric -------------------------------------------- Eric H. Weigle CCS-1, RADIANT team ehw@lanl.gov Los Alamos National Lab (505) 665-4937 http://home.lanl.gov/ehw/ -------------------------------------------- - 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/