From owner-freebsd-net@FreeBSD.ORG Tue Mar 23 13:47:24 2004 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 7E1FA16A4CF for ; Tue, 23 Mar 2004 13:47:24 -0800 (PST) Received: from pit.databus.com (p70-227.acedsl.com [66.114.70.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id E0D2043D2F for ; Tue, 23 Mar 2004 13:47:23 -0800 (PST) (envelope-from barney@pit.databus.com) Received: from pit.databus.com (localhost [127.0.0.1]) by pit.databus.com (8.12.11/8.12.11) with ESMTP id i2NLlN08021312; Tue, 23 Mar 2004 16:47:23 -0500 (EST) (envelope-from barney@pit.databus.com) Received: (from barney@localhost) by pit.databus.com (8.12.11/8.12.11/Submit) id i2NLlN4C021311; Tue, 23 Mar 2004 16:47:23 -0500 (EST) (envelope-from barney) Date: Tue, 23 Mar 2004 16:47:23 -0500 From: Barney Wolff To: Brian Reichert Message-ID: <20040323214723.GA20982@pit.databus.com> References: <20040323203045.GI29783@numachi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040323203045.GI29783@numachi.com> User-Agent: Mutt/1.5.6i X-Scanned-By: MIMEDefang 2.39 cc: freebsd-net@freebsd.org Subject: Re: tricking myself w/ multihoming 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, 23 Mar 2004 21:47:24 -0000 On Tue, Mar 23, 2004 at 03:30:45PM -0500, Brian Reichert wrote: > I think I'm badly misunderstanding the interaction of ipfw and natd > and routing in general. > > I have a multihomed box: > > rl0: flags=8943 mtu 1500 > inet 198.175.254.11 netmask 0xffffff00 broadcast 198.175.254.255 > inet 198.175.254.8 netmask 0xffffffff broadcast 198.175.254.8 > ether 00:30:bd:21:e5:e9 > media: Ethernet autoselect (100baseTX ) > status: active > rl1: flags=8843 mtu 1500 > inet 24.147.155.114 netmask 0xfffff800 broadcast 255.255.255.255 > ether 00:50:ba:8b:64:77 > media: Ethernet autoselect (100baseTX ) > status: active First question, probably irrelevant - how did you get 255.255.255.255 as the broadcast addr on rl1? > The rl1 interface has natd associated with it, and it behaves as expected. > > The default route is also on rl1: > > # netstat -rn | grep default > default 24.147.152.1 UGSc 231 273474 rl1 If 198.175.254.1 is really your external gateway, why is the default route heading inside? Are there so many inside nets that you can't list them as explicit routes? > So far, things are as I wanted, and they've been this way for years. > I can get to this box from my LAN just fine, and NAT works just > fine, and any TCP tunnels on rl1 I've opened up work fine. > > I've gotten it in my head that I want to run a mail server on this box, > publically available via either interface via 198.175.254.8. > > I've modified my firewall rules on this box slightly: > > 00040 fwd 198.175.254.1 tcp from 198.175.254.8 to any 25 > 00050 divert 8668 ip from any to any via rl1 > 00100 allow ip from any to any via lo0 > 00200 deny ip from any to 127.0.0.0/8 > 00300 deny ip from 127.0.0.0/8 to any > 65000 allow ip from any to any > 65535 deny ip from any to any > > (198.175.254.1 is my gateway for the public block.) > > This setup lets outgoing SMTP transactions go out my public block. > > But, seemingly, it does not allow incoming SMTP sessions to occur. Try adding 00045 fwd 198.175.254.1 tcp from 198.175.254.8 25 to any . But really, the problem is better solved by setting your default route to 198.175.254.1 rather than playing ipfw games. How is DNS working? Oh, and please do put some more secure rules in if you're really Internet connected. > Tcpdump on this box shows me the incoming packets coming to > 198.175.254.8, but I'm not seeing these replies to these packets > going out at all, much less to 198.175.254.1. Probably going out rl1. -- Barney Wolff http://www.databus.com/bwresume.pdf I'm available by contract or FT, in the NYC metro area or via the 'Net.