From owner-freebsd-questions@FreeBSD.ORG Fri Mar 11 17:36:22 2005 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 36A6416A4DA for ; Fri, 11 Mar 2005 17:36:22 +0000 (GMT) Received: from smtp11.wanadoo.fr (smtp11.wanadoo.fr [193.252.22.31]) by mx1.FreeBSD.org (Postfix) with ESMTP id DDDBC43D54 for ; Fri, 11 Mar 2005 17:36:21 +0000 (GMT) (envelope-from atkielski.anthony@wanadoo.fr) Received: from me-wanadoo.net (localhost [127.0.0.1]) by mwinf1107.wanadoo.fr (SMTP Server) with ESMTP id 8FE4E1C000A7 for ; Fri, 11 Mar 2005 18:36:20 +0100 (CET) Received: from pix.atkielski.com (ASt-Lambert-111-2-1-3.w81-50.abo.wanadoo.fr [81.50.80.3]) by mwinf1107.wanadoo.fr (SMTP Server) with ESMTP id 6834F1C000A3 for ; Fri, 11 Mar 2005 18:36:20 +0100 (CET) X-ME-UUID: 20050311173620427.6834F1C000A3@mwinf1107.wanadoo.fr Date: Fri, 11 Mar 2005 18:36:20 +0100 From: Anthony Atkielski X-Priority: 3 (Normal) Message-ID: <524507450.20050311183620@wanadoo.fr> To: freebsd-questions@freebsd.org In-Reply-To: <56f756c499c68c62c6706fef0e896cb2@chrononomicon.com> References: <751280160.20050311034539@wanadoo.fr> <1735368246.20050311044408@wanadoo.fr> <56f756c499c68c62c6706fef0e896cb2@chrononomicon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Subject: Re: Clock slew vulnerability in FreeBSD? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: freebsd-questions@freebsd.org List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Mar 2005 17:36:22 -0000 Bart Silverstrim writes: > Wouldn't the skew resolution necessary for this tracking technique > become useless with temperature variations, humidity, etc. that can > affect most systems over the course of the day/week/year? That's one of my questions, too. A technique that could identify 100 million different computers (as some people have speculated) would need reliable precision to at least nine decimal places. That's a pretty tall order for something like measurement of clock slewing in TCP packets. There are other related problems. So you identify computer A using its unique clock slew. How do you prove that in court? If you move the machine, or if you change anything about it, the RTC is likely to vary a bit, changing the slew to a different value. Just temperature variations in the room can do that. -- Anthony