From owner-freebsd-questions Mon Nov 1 17:48:30 1999 Delivered-To: freebsd-questions@freebsd.org Received: from orion.ac.hmc.edu (Orion.AC.HMC.Edu [134.173.32.20]) by hub.freebsd.org (Postfix) with ESMTP id 7326214E30 for ; Mon, 1 Nov 1999 17:48:28 -0800 (PST) (envelope-from brdavis@orion.ac.hmc.edu) Received: (from brdavis@localhost) by orion.ac.hmc.edu (8.8.8/8.8.8) id RAA25732; Mon, 1 Nov 1999 17:45:05 -0800 (PST) Date: Mon, 1 Nov 1999 17:45:05 -0800 From: Brooks Davis To: Oliver Fromme Cc: freebsd-questions@FreeBSD.ORG Subject: Re: How to route a single box into a subnet Message-ID: <19991101174505.C24275@orion.ac.hmc.edu> References: <199911020121.CAA26450@dorifer.heim3.tu-clausthal.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0pre4i In-Reply-To: <199911020121.CAA26450@dorifer.heim3.tu-clausthal.de>; from olli@dorifer.heim3.tu-clausthal.de on Tue, Nov 02, 1999 at 02:21:47AM +0100 Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Tue, Nov 02, 1999 at 02:21:47AM +0100, Oliver Fromme wrote: > We have a /24 subnet (let's call it 1.2.3.0), and for some > technical reason there is one machine (1.2.3.55) that has > to be routed through another machine (1.2.3.44). > > The router (.44) runs FreeBSD -stable and has two network > interfaces -- one is connected to the rest of the network, > and the other is connected directly to the .55 machine (via > a crossed TP cable). The .55 machine has only one network > interface, and it's running various operating systems (W95, > Linux, FreeBSD). > > What is the easiest way to do such a setup? Of course, > the .55 box should have full internet access. All IPs are > static, no dial-up. It is not possible to change the > configuration of other boxes or gateways on the network, > i.e. the routing has to be "hidden" -- I guess that means > that an arp proxy is required. > > At first, I tried to setup the two interfaces of the router > machine like this: > > 1.2.3.44 netmask 255.255.255.0 (the "outer" one) > 1.2.3.45 netmask 255.255.255.255 (the "inner" one) > > and then enable IP forwarding, and run choparp (from ports/ > net) as a proxy arp server. However, it just didn't work. > A simple "ping" resulted in error messages from the arp > resolver ("could not allocate llinfo" or similar -- I can > reproduce it and copy the exact error message if someone > wants to see it). I guess it's because the kernel doesn't > like that the .55 box was not within the network of the .45 > interface of the router (even though the router had a static > route for that box, of course). The chose of .45 and .55 means it won't work that way. If you want to treat a link as though it's on a subnet, then everything you want it to talk to without going through a router must be within the subnet. If you want to deal with it like a subnet you must allocate 4 adjacent (and properly aligned) addresses since you must allocate in powers of two and you must have a broadcast address. > So, what should I try next? Using "private" address spaces > (e.g. 10.x.x.x) between the two boxes, and ipnat on the > router to translate it to the normal .55 address? I still > need an arp proxy in that case, don't I? (I've never done > anything with ipnat or NAT in general before, so I'm a bit > unsure.) If believe you should be able to setup the link between them as a point-to-point link. To do on the router machine just do: ifconfig inet 1.2.3.45 1.2.3.55 Actually, if my tests with ppp over ssh vpns hold true in general you could avoid using a public IP address on the backside of the router by doing something like this: 1.2.3.0/24 <----> [1.2.3.44 10.0.0.1] <---> 1.2.3.55 subnet router PtP Then 1.2.3.55 uses 10.0.0.1 as it's default router. I haven't tested this configuration but I have a system which looks like this which uses many of the same principles: router 1.2.3.0/24 <---> [1.2.3.32 1.2.3.33] <---> 1.2.3.32/28 DSL [ 10.0.1.1 ] Ether ^ | VPN (ppp over ssh) +--> [1.2.3.40] The router in the middle proxies 1.2.3.32/28 on 1.2.3.32 and 1.2.3.40 on 1.2.3.33. -- Brooks To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message