From owner-freebsd-net@FreeBSD.ORG Thu Jan 2 07:13:31 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 5814E7AA for ; Thu, 2 Jan 2014 07:13:31 +0000 (UTC) Received: from h2.funkthat.com (gate2.funkthat.com [208.87.223.18]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 112E31D1D for ; Thu, 2 Jan 2014 07:13:30 +0000 (UTC) Received: from h2.funkthat.com (localhost [127.0.0.1]) by h2.funkthat.com (8.14.3/8.14.3) with ESMTP id s027DTMj011552 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Wed, 1 Jan 2014 23:13:29 -0800 (PST) (envelope-from jmg@h2.funkthat.com) Received: (from jmg@localhost) by h2.funkthat.com (8.14.3/8.14.3/Submit) id s027DSk0011551; Wed, 1 Jan 2014 23:13:28 -0800 (PST) (envelope-from jmg) Date: Wed, 1 Jan 2014 23:13:28 -0800 From: John-Mark Gurney To: Peter Jeremy Subject: Re: IPv4 Multicast MAC Address issues Message-ID: <20140102071328.GW99167@funkthat.com> Mail-Followup-To: Peter Jeremy , freebsd-net@freebsd.org References: <20140101085721.GA34334@server.rulingia.com> <20140101200303.GS99167@funkthat.com> <20140102064356.GL87348@server.rulingia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140102064356.GL87348@server.rulingia.com> User-Agent: Mutt/1.4.2.3i X-Operating-System: FreeBSD 7.2-RELEASE i386 X-PGP-Fingerprint: 54BA 873B 6515 3F10 9E88 9322 9CB1 8F74 6D3F A396 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html X-to-the-FBI-CIA-and-NSA: HI! HOW YA DOIN? can i haz chizburger? X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.2 (h2.funkthat.com [127.0.0.1]); Wed, 01 Jan 2014 23:13:29 -0800 (PST) Cc: freebsd-net@freebsd.org X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 02 Jan 2014 07:13:31 -0000 Peter Jeremy wrote this message on Thu, Jan 02, 2014 at 17:43 +1100: > On 2014-Jan-01 12:03:04 -0800, John-Mark Gurney wrote: > >Peter Jeremy wrote this message on Wed, Jan 01, 2014 at 19:57 +1100: > >> I'm trying to use multicast on my home network for the first time and > >> have found an apparent anomoly in the destination MAC address. > ... > >> FreeBSD shows that as the multicast MAC filter. Unfortunately, it > >> seems that (at least on FreeBSD-10), the destination MAC address > >> uses the low 23 bits of the IP address of my default route. > > >This is probably a bug, and I have confirmed this on: > >FreeBSD carbon.funkthat.com 11.0-CURRENT FreeBSD 11.0-CURRENT #4 r256870:258399M: Wed Nov 20 12:33:22 PST 2013 jmg@carbon.funkthat.com:/usr/src/sys/amd64/compile/lockprof amd64 > > Thanks. I've since checked 9.2/amd64 and it's OK there, so this is a > regression. I've raised kern/185395. I've done a quick look at the code and I don't see anything that changed that is odd, but I did notice that ETHER_MAP_IP_MULTICAST in if_ether.h doesn't put parens around ipaddr, but it's only use in if_ether.c looks safe. The one change around this code is the addition of const in the macro, but I don't think that could cause the issue... Hmmm... looking at the comments for arpresolve, it says dst is the next hop which would be the gateway, and not the multicast address, so that could be it, but I don't know the code well enough to figure out why dst isn't the multicast address... -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."