Date: Fri, 11 Mar 2005 04:44:08 +0100 From: Anthony Atkielski <atkielski.anthony@wanadoo.fr> To: freebsd-questions@freebsd.org Subject: Re: Clock slew vulnerability in FreeBSD? Message-ID: <1735368246.20050311044408@wanadoo.fr> In-Reply-To: <20050311025906.GD72527@hub.freebsd.org> References: <751280160.20050311034539@wanadoo.fr> <20050311025906.GD72527@hub.freebsd.org>
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Kris Kennaway writes: > Isn't this a non-problem if you use ntpd? Unfortunately, no, because the TCP stacks on most systems don't use the disciplined clock provided by NTP for the timestamps. Instead they use a clock based directly on the RTC, which reveals a characteristic skew that is unique to each machine. If the stacks used the NTP-disciplined actual time of day, plus perhaps a randomizing factor to avoid revealing patterns, this technique would become useless. -- Anthony
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