Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 25 Nov 2000 19:42:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 25 Nov 2000 19:42:50 -0500 Received: from altrade.nijmegen.inter.nl.net ([193.67.237.6]:19689 "EHLO altrade.nijmegen.inter.nl.net") by vger.kernel.org with ESMTP id ; Sat, 25 Nov 2000 19:42:40 -0500 Date: Sun, 26 Nov 2000 00:55:38 +0100 From: Frank van Maarseveen To: linux-kernel@vger.kernel.org Subject: 2.4.0-test11 af_packet/tcpdump/routing bug? Message-ID: <20001126005538.A10587@iapetus.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org The tcpdump program (tcpdump -p -i ppp1 -s 1500 not port login) will not report any packets after adding a default route to eth0 in the setup below. The packet generating command is ping 192.168.2.42 It has been verified at the ppp1 peer that packets really arrive there via ppp. Tcpdumping eth0 locally also confirms that packets don't go via eth0. After adding/deleting the default route tcpdump needs to be restarted to notice the difference. It uses the af_packet kernel module and maybe its usage count must drop to zero temporarily to make a difference (I don't know). iapetus ~# route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.2.42 * 255.255.255.255 UH 0 0 0 ppp1 192.168.0.39 * 255.255.255.255 UH 0 0 0 eth0 192.168.2.0 * 255.255.255.0 U 0 0 0 eth0 localnet * 255.255.255.0 U 0 0 0 eth0 loopback * 255.0.0.0 U 0 0 0 lo iapetus ~# ifconfig eth0 Link encap:Ethernet HWaddr 00:50:04:21:99:04 inet addr:192.168.0.39 Bcast:192.168.0.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:34216 errors:0 dropped:0 overruns:0 frame:0 TX packets:52668 errors:0 dropped:0 overruns:0 carrier:5 collisions:117 txqueuelen:100 Interrupt:10 Base address:0x300 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:16144 Metric:1 RX packets:16037 errors:0 dropped:0 overruns:0 frame:0 TX packets:16037 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 ppp1 Link encap:Point-to-Point Protocol inet addr:192.168.2.201 P-t-P:192.168.2.42 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1 RX packets:331 errors:0 dropped:0 overruns:0 frame:0 TX packets:330 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:3 Adding a default route: iapetus ~# route add default dev eth0 iapetus ~# route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.2.42 * 255.255.255.255 UH 0 0 0 ppp1 192.168.0.39 * 255.255.255.255 UH 0 0 0 eth0 192.168.2.0 * 255.255.255.0 U 0 0 0 eth0 localnet * 255.255.255.0 U 0 0 0 eth0 loopback * 255.0.0.0 U 0 0 0 lo default * 0.0.0.0 U 0 0 0 eth0 -- Frank - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/