From owner-freebsd-security Mon Aug 21 15:18:27 2000 Delivered-To: freebsd-security@freebsd.org Received: from jade.chc-chimes.com (jade.chc-chimes.com [216.28.46.6]) by hub.freebsd.org (Postfix) with ESMTP id 0A15137B423 for ; Mon, 21 Aug 2000 15:18:26 -0700 (PDT) Received: by jade.chc-chimes.com (Postfix, from userid 1001) id 965761C6D; Mon, 21 Aug 2000 18:18:25 -0400 (EDT) Date: Mon, 21 Aug 2000 18:18:25 -0400 From: Bill Fumerola To: "Rodney W. Grimes" Cc: William Wong , freebsd-security@FreeBSD.ORG Subject: Re: icmptypes Message-ID: <20000821181825.I57333@jade.chc-chimes.com> References: <20000821180351.H57333@jade.chc-chimes.com> <200008212216.PAA31247@gndrsh.dnsmgr.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0i In-Reply-To: <200008212216.PAA31247@gndrsh.dnsmgr.net>; from freebsd@gndrsh.dnsmgr.net on Mon, Aug 21, 2000 at 03:16:03PM -0700 X-Operating-System: FreeBSD 3.3-STABLE i386 Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Mon, Aug 21, 2000 at 03:16:03PM -0700, Rodney W. Grimes wrote: > > example from memory: > > # ipfw add unreach filter-prohib icmp from any to any icmptypes 0,8 > > The 8 case would be okay, but returning an icmp unreach for an icmp echo > reply would be a violation of the protocol spec. I would recomend > against it. Yes, unreaching 0 would be nonsense I suppose. On a side note, RFC and protocol blah blah is nice, but sometimes you just have to drop packets and break spec if the machine is a target. If this is being used as a border firewall or some such, then I would certainly heed Rod's advice on being careful what to break. For a single machine, I'd be less worried. -- Bill Fumerola - Network Architect, BOFH / Chimes, Inc. billf@chimesnet.com / billf@FreeBSD.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message