From owner-freebsd-current@FreeBSD.ORG Thu Oct 2 09:07:30 2003 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 93DD816A4C1 for ; Thu, 2 Oct 2003 09:07:30 -0700 (PDT) Received: from main.gmane.org (main.gmane.org [80.91.224.249]) by mx1.FreeBSD.org (Postfix) with ESMTP id 39A2843FE5 for ; Thu, 2 Oct 2003 09:07:28 -0700 (PDT) (envelope-from freebsd-current@m.gmane.org) Received: from list by main.gmane.org with local (Exim 3.35 #1 (Debian)) id 1A55zC-0002Oe-00 for ; Thu, 02 Oct 2003 18:07:26 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: freebsd-current@freebsd.org Received: from sea.gmane.org ([80.91.224.252]) by main.gmane.org with esmtp (Exim 3.35 #1 (Debian)) id 1A55zB-0002OW-00 for ; Thu, 02 Oct 2003 18:07:25 +0200 Received: from news by sea.gmane.org with local (Exim 3.35 #1 (Debian)) id 1A55zB-0001fF-00 for ; Thu, 02 Oct 2003 18:07:25 +0200 From: othermark Date: Thu, 2 Oct 2003 16:07:25 +0000 (UTC) Lines: 55 Message-ID: X-Complaints-To: usenet@sea.gmane.org User-Agent: tin/1.6.1-20030810 ("Mingulay") (UNIX) (FreeBSD/4.9-PRERELEASE (i386)) User-Agent: tin/1.6.1-20030810 ("Mingulay") (UNIX) (FreeBSD/4.9-PRERELEASE (i386)) Sender: news Subject: ipv6: Strange packet leaked locally to bpf with fxp. X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 02 Oct 2003 16:07:30 -0000 Hi, I'm seeing a strange packet in tcpdump when sending ICMP6 echo-requests to the all nodes multicast address (ff02::1) in both -stable and -current. This packet does not appear to get out over the wire, since a 3rd party host will not observe this packet when attached to a real hub. However when capturing locally, this packet appears before and after the ICMP6 echo request. These packets seem to contain the ipv6 packet to be sent but offset incorrectly and with the wrong data. The destination MAC address seems to be the start of the ipv6 packet. What are these null I packets? Are they particular to fxp? [root@nemo root]$ tcpdump -vvvvi fxp3 tcpdump: listening on fxp3 08:05:20.213988 3a:40:fe:80:0:0 > 60:0:0:0:0:10 null I (s=1,r=112,C) len=38 81ff fe00 f6bf ff02 0000 0000 0000 0000 0000 0000 0001 8000 e7c9 3904 0000 b03e 7c3f b843 0300 08:05:20.214004 fe80::2e0:81ff:fe00:f6bf > ff02::1: icmp6: echo request (len 16, hlim 64) 08:05:20.214044 3a:40:fe:80:0:0 > 60:0:0:0:0:10 null I (s=1,r=112,C) len=38 81ff fe00 f6bf fe80 0000 0000 0000 02e0 81ff fe00 f6bf 8100 6dac 3904 0000 b03e 7c3f b843 0300 08:05:21.218031 3a:40:fe:80:0:0 > 60:0:0:0:0:10 null I (s=1,r=112,C) len=38 81ff fe00 f6bf ff02 0000 0000 0000 0000 0000 0000 0001 8000 1eb9 3904 0001 b13e 7c3f 8053 0300 08:05:21.218047 fe80::2e0:81ff:fe00:f6bf > ff02::1: icmp6: echo request (len 16, hlim 64) 08:05:21.218086 3a:40:fe:80:0:0 > 60:0:0:0:0:10 null I (s=1,r=112,C) len=38 81ff fe00 f6bf fe80 0000 0000 0000 02e0 81ff fe00 f6bf 8100 a49b 3904 0001 b13e 7c3f 8053 0300 08:05:22.208128 3a:40:fe:80:0:0 > 60:0:0:0:0:10 null I (s=1,r=112,C) len=38 81ff fe00 f6bf ff02 0000 0000 0000 0000 0000 0000 0001 8000 cade 3904 0002 b23e 7c3f d32c 0300 08:05:22.208143 fe80::2e0:81ff:fe00:f6bf > ff02::1: icmp6: echo request (len 16, hlim 64) 08:05:22.208183 3a:40:fe:80:0:0 > 60:0:0:0:0:10 null I (s=1,r=112,C) len=38 81ff fe00 f6bf fe80 0000 0000 0000 02e0 81ff fe00 f6bf 8100 50c1 3904 0002 b23e 7c3f d32c 0300 ^C 9 packets received by filter 0 packets dropped by kernel Note that ipv6 works fine, it's just that these packets prevent me from verifying that my other hardware isn't leaking or misformatting packets. All the best, Mark atkin901 at nospam dot yahoo dot com (!wired)?(coffee++):(wired);