From owner-freebsd-questions Mon Oct 8 20:32:29 2001 Delivered-To: freebsd-questions@freebsd.org Received: from chmls06.mediaone.net (chmls06.mediaone.net [24.147.1.144]) by hub.freebsd.org (Postfix) with ESMTP id D501F37B405 for ; Mon, 8 Oct 2001 20:32:25 -0700 (PDT) Received: from acadia.ne.mediaone.net (acadia.ne.mediaone.net [65.96.185.189]) by chmls06.mediaone.net (8.11.1/8.11.1) with ESMTP id f993Wfh13826 for ; Mon, 8 Oct 2001 23:32:42 -0400 (EDT) Received: (from leblanc@localhost) by acadia.ne.mediaone.net (8.11.6/8.11.5) id f993WK204323 for freebsd-questions@FreeBSD.org; Mon, 8 Oct 2001 23:32:20 -0400 (EDT) (envelope-from leblanc) Date: Mon, 8 Oct 2001 23:32:20 -0400 From: Louis LeBlanc To: freebsd-questions@FreeBSD.org Subject: Another firewall question - spoofing prevention and syntax Message-ID: <20011008233219.C589@acadia.ne.mediaone.net> Reply-To: freebsd-questions@FreeBSD.org Mail-Followup-To: freebsd-questions@FreeBSD.org Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit User-Agent: Mutt/1.3.22.1i X-bright-idea: Lets abolish HTML mail! Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Another firewall question, not for the faint of heart: Is the following valid? # Refuse incoming packets pretending to be from the external address. ipfw add deny log all from $IPADDR to any via (null) in # Refuse incoming packets claiming to be from a Class A, B or C private network ipfw add deny all from $CLASS_A to any via (null) in ipfw add deny all from $CLASS_B to any via (null) in ipfw add deny all from $CLASS_C to any via (null) in I can't find any reference to the use of (null) as the interface name to prevent spoofing, but the tool I use online does this automagically. Any ideas? TIA & HAND Lou -- Louis LeBlanc leblanc@acadia.ne.mediaone.net Fully Funded Hobbyist, KeySlapper Extrordinaire :) http://acadia.ne.mediaone.net ԿԬ QOTD: Y'know how s'm people treat th'r body like a TEMPLE? Well, I treat mine like 'n AMUSEMENT PARK... S'great... To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message