From owner-freebsd-questions Thu Feb 27 08:30:22 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id IAA05322 for questions-outgoing; Thu, 27 Feb 1997 08:30:22 -0800 (PST) Received: from xmission.xmission.com (softweyr@xmission.xmission.com [198.60.22.2]) by freefall.freebsd.org (8.8.5/8.8.5) with ESMTP id IAA05316 for ; Thu, 27 Feb 1997 08:30:18 -0800 (PST) Received: (from softweyr@localhost) by xmission.xmission.com (8.8.5/8.7.5) id JAA17649; Thu, 27 Feb 1997 09:30:11 -0700 (MST) From: Softweyr LLC Message-Id: <199702271630.JAA17649@xmission.xmission.com> Subject: Re: forwarding broadcast packets between interfaces To: dg@root.com Date: Thu, 27 Feb 1997 09:30:10 -0700 (MST) Cc: questions@freebsd.org In-Reply-To: <199702271404.GAA04752@root.com> from "David Greenman" at Feb 27, 97 06:04:34 am X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-questions@freebsd.org X-Loop: FreeBSD.org Precedence: bulk David Greenman recently enlightened us thusly: > Broadcasts have nothing to do with UDP packets other than a UDP packet, > like any other IP packet, may or may not be sent to a broadcast address. > It is true that packets sent to the broadcast address are not routed through > the gateway, and aside from creative mis-configuration, there isn't any way > you can get the gateway to pass them through, either. Exactly right; the same is true of multicasts. There are situations in which you want to route multicasts, or even broadcasts, between two networks, but they are few and far between. About the only router maker that really understands this is Cisco. You could probably fake it to some extent with a FreeBSD router with some creative route table manipulations, but chances are pretty good you'll just screw up routing to the point where it doesn't work at all. In general, if you want to share broadcasts or multicasts between two networks, you need bridges rather than routers. The idea of a broadcast packet being literally sent to every computer attached to the internet gives me the creeping willies. What an abuse! -- "Where am I, and what am I doing in this handbasket?" Wes Peters Softweyr LLC http://www.xmission.com/~softweyr softweyr@xmission.com