From owner-freebsd-questions@FreeBSD.ORG Fri Sep 21 05:22:22 2007 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7BB9D16A468 for ; Fri, 21 Sep 2007 05:22:22 +0000 (UTC) (envelope-from sandiegobiker@gmail.com) Received: from an-out-0708.google.com (an-out-0708.google.com [209.85.132.249]) by mx1.freebsd.org (Postfix) with ESMTP id 34ED513C447 for ; Fri, 21 Sep 2007 05:22:22 +0000 (UTC) (envelope-from sandiegobiker@gmail.com) Received: by an-out-0708.google.com with SMTP id c14so164687anc for ; Thu, 20 Sep 2007 22:22:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; bh=08IATmpguw7wh4nH9URZFuERaXv68eOZ0unF4JCpzuI=; b=WwUzXuXZNLSzPKThwLLnqr9iPVfhjA31NZxUIRxSdlV3wN0WhEr1W4cEWLtYA0pryWesSHcemT8Hr0tFo94p7hLGDdgjCUGeeTkYLFkqr/crsTG4fhb6qLvATmOKcTY8aZYJHuY7AZfDJP63FrAJISJI+UUuhgHKbumdRYHvO48= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=A3s1qqoX+sm/ASdnGsjo3c05JsHIm9O6jW/ffPeUMTT9adurEGLuuIajgj8Uu+lC80UbdQZd9PKhIEtRdwX5o5PvyfJP11rz2vFLmAOoIdGP0Nu3ukivYqF3GXoqbGRejFl5a0s4Bfp3qnIm75bNcdyfHgGU24S7satLqffRupY= Received: by 10.100.10.20 with SMTP id 20mr1216105anj.1190352141424; Thu, 20 Sep 2007 22:22:21 -0700 (PDT) Received: by 10.70.102.1 with HTTP; Thu, 20 Sep 2007 22:22:21 -0700 (PDT) Message-ID: <27cb3ada0709202222w7af08809s2e7c8d79c5c7880b@mail.gmail.com> Date: Thu, 20 Sep 2007 22:22:21 -0700 From: "Len Gross" To: "freebsd-questions@freebsd.org" In-Reply-To: <448x71nfmx.fsf@Lowell-Desk.lan> MIME-Version: 1.0 References: <27cb3ada0709161413i163d942cld279e92634d06001@mail.gmail.com> <448x71nfmx.fsf@Lowell-Desk.lan> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Subject: Re: Multiple NICs - custom protocol development X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 21 Sep 2007 05:22:22 -0000 First, thanks for the response; It's nice to see some community support. Here is what I am trying to do: I am building a custom MAC protocol for a wireless system that has different software on the "head end" and the "clients." It is not peer-to-peer, While the hardware is being developed I want to use Ethernet as a physical layer. So,I want to use one card running server code and one card running client code initially. Later I will do the checkout with multiple client machines and a single server. If the OS "loops a packet back" (At the IP layer) before it gets to my "MAC layer" then I can't test any code. -- Len On 9/20/07, Lowell Gilbert wrote: > > "Len Gross" writes: > > > I have a host on my local 192.168.0 / 24 subnet that works fine in > getting > > to the Internet via a default route.via a wireless connection. > > I want to develop some custom link protocols and I have placed two > Ethernet > > NICs in the box. > > I want to be able to send packets from one NIC to the other and maintain > the > > link to the Internet. > > I've tried a large number of things via rc.conf but when I ping of the > cards > > it is not going out the interface; it just gets looped back. (I test > this > > by disconnecting the "crossover cable" between the two cards.) > > > > My current rc.conf has the following attempt, but this fails. > > > > # > > router_enable="Yes" > > gateway_enable="Yes" > > # Ethernet 1: > > ifconfig_xl0="inet 192.168.1.1 netmask 255.255.255.0" > > # Ethernet 2 > > ifconfig_rl0="inet 192.168.2.1 netmask 255.255.255.0" > > # > > # Set up loop between the two ethernet cards > > static_routes "xtor, rtox" > > route_rtox = "-host 192.168.1.1 192.168.2.1" > > route_xtor = "-host 192.168.2.1 192.168.1.1" > > > > Can I do what I want or must I have a second development box? > > What you want to do doesn't make sense; there is no reason to send > packets to yourself over a wire. If your machine is sending packets > to itself, the best path is over the loopback, and it doesn't make > sense to send it over a different path. So you need to examine *why* > you want to do that before you can figure out the best approach to > your root problem. > > I do protocol development and testing through a number of different > approaches, but for basic development there's usually no problem with > letting the packets go over the loopback. For working on something > like DHCP, I need separate IP stacks, because that will modify the > routing tables differently on the server and the client(s). For that, > I find virtual machines (qemu, most recently) to be the easiest and > most flexible environment. I have also used environments based on > bpf(4) interfaces when I was working with IP stacks that ran > separately from the system's kernel. > > Good luck. >