Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752123AbWAEJUt (ORCPT ); Thu, 5 Jan 2006 04:20:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752127AbWAEJUt (ORCPT ); Thu, 5 Jan 2006 04:20:49 -0500 Received: from 213-140-2-68.ip.fastwebnet.it ([213.140.2.68]:39337 "EHLO aa001msg.fastwebnet.it") by vger.kernel.org with ESMTP id S1752123AbWAEJUs (ORCPT ); Thu, 5 Jan 2006 04:20:48 -0500 Date: Thu, 5 Jan 2006 10:20:54 +0100 From: JohnnyRun To: linux-kernel@vger.kernel.org Subject: eth0 and loopback problems. Message-ID: <20060105092052.GE3008@darkstar.mylan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1708 Lines: 54 Hi all! I think it's a bug.... HOSTA# ifconfig eth0 192.168.0.1 HOSTA# ifconfig eth0 down HOSTA# ping 192.168.0.1 (the ping works, like all other ICMP / TCP /UDP ... application. In other words: all work like eth0 in UP mode when source and destination point comunicate via loopback device. I think it's not correct because if eth0 is DOWN for all the hosts in LAN should be down for me too. Or not? Suppose another conf: HOSTA# ifconfig eth0 Link encap:Ethernet HWaddr 00:10:DC:C3:5E:FF inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.0.0.0 BROADCAST MULTICAST MTU:1500 Metric:1 eth1 Link encap:Ethernet HWaddr 00:0E:35:74:16:67 inet addr:192.168.0.2 [...] UP BROADCAST RUNNING MULTICAST MTU:1500 lo [...] HOSTB# ifconfig eth0 eth0 Link encap:Ethernet HWaddr 00:00:24:C8:4A:7D inet addr:192.168.0.1 Bcast:1.255.255.255 Mask:255.0.0.0 UP BROADCAST RUNNING MULTICAST MTU:1500 [...] So, HOSTA and HOSTB share the same ip but: HOSTA eth0 is DOWN; HOSTA eth1 is UP, HOSTB eth0 is UP. So, no conflict should be possible. but: HOSTB# ping 192.168.0.2 (does not reply) So I suppose that HOSTA route the icmp reply through its lo. But: HOSTA# tcpdump -i lo doesn't show any reply, and HOSTA# tcpdump -i eth0 it's not permitted, because eth0 is DOWN. The same result for TCP protocol (tested with hping). Operative conditions: Linux 2.6.14, HOSTA eth1 is wifi. Regards JohnnyRun - 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/