From owner-freebsd-ipfw Wed Mar 12 0:15:40 2003 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 6D3BE37B401 for ; Wed, 12 Mar 2003 00:15:39 -0800 (PST) Received: from sccrmhc01.attbi.com (sccrmhc01.attbi.com [204.127.202.61]) by mx1.FreeBSD.org (Postfix) with ESMTP id 957F743F85 for ; Wed, 12 Mar 2003 00:15:38 -0800 (PST) (envelope-from crist.clark@attbi.com) Received: from blossom.cjclark.org (12-234-89-252.client.attbi.com[12.234.89.252]) by sccrmhc01.attbi.com (sccrmhc01) with ESMTP id <200303120815370010039afde>; Wed, 12 Mar 2003 08:15:37 +0000 Received: from blossom.cjclark.org (localhost. [127.0.0.1]) by blossom.cjclark.org (8.12.6/8.12.3) with ESMTP id h2C8Faeq042991 for ; Wed, 12 Mar 2003 00:15:36 -0800 (PST) (envelope-from crist.clark@attbi.com) Received: (from cjc@localhost) by blossom.cjclark.org (8.12.6/8.12.6/Submit) id h2C8FaFl042990 for ipfw@freebsd.org; Wed, 12 Mar 2003 00:15:36 -0800 (PST) X-Authentication-Warning: blossom.cjclark.org: cjc set sender to crist.clark@attbi.com using -f Date: Wed, 12 Mar 2003 00:15:36 -0800 From: "Crist J. Clark" To: ipfw@freebsd.org Subject: Re: Anti-Spoofing Option Message-ID: <20030312081536.GB42446@blossom.cjclark.org> Reply-To: "Crist J. Clark" References: <20030312080622.GA42446@blossom.cjclark.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030312080622.GA42446@blossom.cjclark.org> 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 Wed, Mar 12, 2003 at 12:06:22AM -0800, Crist J. Clark wrote: [snip] > To turn on anti-spoofing on a firewall, put, > > # ipfw add 100 pass ip from any to any verrevpath > > Before any other rules. All done (well, only if you're not using > dynamic rules). Whoa. Must be getting late. You probably don't want to do that on your firewall. That was for showing the only rule you need on a router where you only want to enable antispoofing. To turn on anti-spoofing for a stateless packet filter, start with, # ipfw add 100 deny ip from any to any not verrevpath in That is deny incoming packets that don't pass the 'verrevpath' check. -- 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