Date: Thu, 20 Sep 2007 18:20:06 -0400 From: Lowell Gilbert <freebsd-questions-local@be-well.ilk.org> To: "Len Gross" <sandiegobiker@gmail.com> Cc: "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org> Subject: Re: Multiple NICs - custom protocol development Message-ID: <448x71nfmx.fsf@Lowell-Desk.lan> In-Reply-To: <27cb3ada0709161413i163d942cld279e92634d06001@mail.gmail.com> (Len Gross's message of "Sun\, 16 Sep 2007 14\:13\:33 -0700") References: <27cb3ada0709161413i163d942cld279e92634d06001@mail.gmail.com>
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"Len Gross" <sandiegobiker@gmail.com> 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.
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