From owner-freebsd-security@FreeBSD.ORG Wed Apr 21 04:51:56 2004 Return-Path: Delivered-To: freebsd-security@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5FF6A16A4CE; Wed, 21 Apr 2004 04:51:56 -0700 (PDT) Received: from gw.celabo.org (gw.celabo.org [208.42.49.153]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2544443D54; Wed, 21 Apr 2004 04:51:56 -0700 (PDT) (envelope-from nectar@celabo.org) Received: from localhost (localhost [127.0.0.1]) by gw.celabo.org (Postfix) with ESMTP id AC50754840; Wed, 21 Apr 2004 06:51:55 -0500 (CDT) Received: from gw.celabo.org ([127.0.0.1]) by localhost (hellblazer.celabo.org [127.0.0.1]) (amavisd-new, port 10024) with SMTP id 84127-05; Wed, 21 Apr 2004 06:51:45 -0500 (CDT) Received: from lum.celabo.org (lum.celabo.org [10.0.1.107]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "lum.celabo.org", Issuer "celabo.org CA" (verified OK)) by gw.celabo.org (Postfix) with ESMTP id B9AE65487F; Wed, 21 Apr 2004 06:51:24 -0500 (CDT) Received: by lum.celabo.org (Postfix, from userid 501) id 779BF1D0B03; Wed, 21 Apr 2004 06:07:04 -0500 (CDT) Date: Wed, 21 Apr 2004 06:07:04 -0500 From: "Jacques A. Vidrine" To: Mike Silbersack Message-ID: <20040421110704.GA19640@lum.celabo.org> Mail-Followup-To: "Jacques A. Vidrine" , Mike Silbersack , Don Lewis , freebsd-security@FreeBSD.org, avalon@caligula.anu.edu.au References: <200404210346.i3L3ki7E045504@gw.catspoiler.org> <20040421014736.H1228@odysseus.silby.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040421014736.H1228@odysseus.silby.com> X-Url: http://www.celabo.org/ User-Agent: Mutt/1.5.6i cc: freebsd-security@FreeBSD.org cc: Don Lewis cc: avalon@caligula.anu.edu.au Subject: Re: [Full-Disclosure] IETF Draft - Fix for TCP vulnerability (fwd) X-BeenThere: freebsd-security@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Security issues [members-only posting] List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Apr 2004 11:51:56 -0000 On Wed, Apr 21, 2004 at 01:50:28AM -0500, Mike Silbersack wrote: > > On Tue, 20 Apr 2004, Don Lewis wrote: > > > I am concerned that step C will not solve the compatibility problem. The > > FreeBSD host is sending a FIN to close an established connection, and > > the peer host adding the window size advertised in the FIN packet to the > > sequence number acknowledged in the FIN packet, and using the sum as the > > sequence number for the RST packet, which puts the sequence number at > > the end of the receive window. > > Would it be feasible for us to create a four to five element array to > track "resettable" sequence numbers? This could hold the sequence numbers > of the last few packets transmitted, and account for that edge case as > well. I'm very uneasy with the IETF step C - sending more packets out > into the network sounds like a new type of amplification attack. I'm also somewhat skeptical. Considering the attack that this is supposed to mitigate, it would probably be a good idea to implement this as a compile time option defaulting OFF at first. Those really worried about an attack (running BGP?) can utilize it, as well as those testing interoperability for awhile. Cheers, -- Jacques Vidrine / nectar@celabo.org / jvidrine@verio.net / nectar@freebsd.org