From owner-freebsd-ipfw Wed Oct 9 13:41:30 2002 Delivered-To: freebsd-ipfw@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9013637B401 for ; Wed, 9 Oct 2002 13:41:29 -0700 (PDT) Received: from sccrmhc02.attbi.com (sccrmhc02.attbi.com [204.127.202.62]) by mx1.FreeBSD.org (Postfix) with ESMTP id F056E43E3B for ; Wed, 9 Oct 2002 13:41:28 -0700 (PDT) (envelope-from crist.clark@attbi.com) Received: from blossom.cjclark.org ([12.234.91.48]) by sccrmhc02.attbi.com (InterMail vM.4.01.03.27 201-229-121-127-20010626) with ESMTP id <20021009204128.JFKK6765.sccrmhc02.attbi.com@blossom.cjclark.org>; Wed, 9 Oct 2002 20:41:28 +0000 Received: from blossom.cjclark.org (localhost. [127.0.0.1]) by blossom.cjclark.org (8.12.3/8.12.3) with ESMTP id g99KfRWn064889; Wed, 9 Oct 2002 13:41:27 -0700 (PDT) (envelope-from crist.clark@attbi.com) Received: (from cjc@localhost) by blossom.cjclark.org (8.12.3/8.12.3/Submit) id g99KfQ3J064883; Wed, 9 Oct 2002 13:41:26 -0700 (PDT) X-Authentication-Warning: blossom.cjclark.org: cjc set sender to crist.clark@attbi.com using -f Date: Wed, 9 Oct 2002 13:41:26 -0700 From: "Crist J. Clark" To: Danny.Carroll@mail.ing.nl Cc: ipfw@FreeBSD.ORG Subject: Re: Question about to/from matching. Message-ID: <20021009204126.GB64287@blossom.cjclark.org> Reply-To: "Crist J. Clark" References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4i X-URL: http://people.freebsd.org/~cjc/ Sender: owner-freebsd-ipfw@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Fri, Oct 04, 2002 at 01:14:00PM +0200, Danny.Carroll@mail.ing.nl wrote: > I have not got my copy of "Internetworking with TCP/IP Vol. x" with me (someone borrowed it indefinatly) so forgive this rather basic question. > > I have a rule, very early in my ruleset that says: > deny log ip from any to 10.0.0.0/8 via xl0 > > but my gateway (and default route) is 10.0.0.100 > > Now, it's working the way I want it to... In that it sends outside stuff to 10.0.0.100 and I can't telnet directly to the gateway. But I am curious why this rule does not get inforced. It does get enforced. You said you cannot telnet to 10.0.0.100. > What does a TCP packet look like when it's being sent *to* a remote destination, but via a gateway. Does the ip stack translate 10.0.0.100 to an ethernet address and pass it on that way? Yes. The gateway's IP address doesn't appear in the IP packet. Have a look at the packet. Use tcpdump(8) with '-X' and look diagram of the data fields in an IP datagram. -- Crist J. Clark | cjclark@alum.mit.edu | cjclark@jhu.edu http://people.freebsd.org/~cjc/ | cjc@freebsd.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-ipfw" in the body of the message