From owner-freebsd-net@FreeBSD.ORG Mon Oct 20 17:42:59 2003 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D8FF416A4B3 for ; Mon, 20 Oct 2003 17:42:59 -0700 (PDT) Received: from pit.databus.com (p70-227.acedsl.com [66.114.70.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id D830C43FAF for ; Mon, 20 Oct 2003 17:42:58 -0700 (PDT) (envelope-from barney@pit.databus.com) Received: from pit.databus.com (localhost [127.0.0.1]) by pit.databus.com (8.12.9p2/8.12.9) with ESMTP id h9L0goYL068333; Mon, 20 Oct 2003 20:42:51 -0400 (EDT) (envelope-from barney@pit.databus.com) Received: (from barney@localhost) by pit.databus.com (8.12.9p2/8.12.9/Submit) id h9L0goA4068332; Mon, 20 Oct 2003 20:42:50 -0400 (EDT) (envelope-from barney) Date: Mon, 20 Oct 2003 20:42:50 -0400 From: Barney Wolff To: Wes Peters Message-ID: <20031021004250.GA68072@pit.databus.com> References: <20031020174751.60464.qmail@web20805.mail.yahoo.com> <20031020190019.GD8721@saboteur.dek.spc.org> <20031020194959.GA64879@pit.databus.com> <200310201521.26705.wes@softweyr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200310201521.26705.wes@softweyr.com> User-Agent: Mutt/1.4.1i X-Scanned-By: MIMEDefang 2.37 cc: freebsd-net@freebsd.org cc: mgrooms@shrew.net cc: sarat chandra Annadata cc: julian@elischer.org Subject: Re: Help Broadcasting a UDP packet on the LAN:URGENT X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 21 Oct 2003 00:43:00 -0000 On Mon, Oct 20, 2003 at 03:21:26PM -0700, Wes Peters wrote: > > But does it send the packet to all attached interfaces on a multi-homed > host? This is the type of bug that has typically bitten such hackish > solutions in the past. One real solution is worth much more than the > sum of the sort-of but not really working hacks we have flying about > now. Bughood is in the eye of the beholder. RFC1122 has this to say, in section 3.3.6: (255.255.255.255 is the "Limited Broadcast" address) There has been discussion on whether a datagram addressed to the Limited Broadcast address ought to be sent from all the interfaces of a multihomed host. This specification takes no stand on the issue. And of course any application that actually needs to send such a packet on every interface can loop through the interfaces, using the technique on each one, getting the reply, removing the 255.0.0.0/8 alias, and moving on to the next interface. If it were up to me (as of course it is not) I'd leave it at that and not clutter up the kernel. -- Barney Wolff http://www.databus.com/bwresume.pdf I'm available by contract or FT, in the NYC metro area or via the 'Net.