Date: Wed, 23 Apr 2003 13:16:24 -0400 From: Bill Moran <wmoran@potentialtech.com> To: David Kelly <dkelly@hiwaay.net> Cc: Joel Rees <joel@alpsgiken.gr.jp> Subject: Re: Accurate time without a network connection? Message-ID: <3EA6CA68.1060902@potentialtech.com> In-Reply-To: <20030423161358.GA24633@grumpy.dyndns.org> References: <4B518202-74F8-11D7-BCB7-003065ABFD92@mac.com> <20030422194413.GC13774@grumpy.dyndns.org> <20030423175412.B1F6.JOEL@alpsgiken.gr.jp> <20030423161358.GA24633@grumpy.dyndns.org>
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David Kelly wrote: > On Wed, Apr 23, 2003 at 05:58:47PM +0900, Joel Rees wrote: > >>>On Tue, Apr 22, 2003 at 03:26:19PM -0400, Charles Swiger wrote: >>> >>>As for exactly what time the systems have, it doesn't much matter as >>>long as they all have the same time. >> >>If you're serious about it not mattering exactly what time they have, >>what's the problem with letting one machine be the time server, letting >>it tune itself and then free run, and syncing all the rest to the >>slightly-off-time-server? > > Because the other systems do not have a link to the first. > > I could sync them all to a common source they could *hear* but the > customer won't allow them to *talk* to anything. I've recently become interested in the theory behind NTP and timekeeping in general (because of situations in my work that have gotten me interested) and have followed this thread with some curiousity. Mind if I ask some rather off-the-wall questions to possible formulate some out-of-the box ideas? What, exactly, is the environment you are doing this in? If I remember previous posts correctly: You need time keeping, it doesn't have to be very accurate, or even "correct" (to the degree that the time could be outright wrong as long as it's consistent within the company - did I undestand that right?) The machine in question is not permitted to access ANYTHING via a network, even other machines withing the company? First off, can you explain the rational behind this? It sounds crazy to me. Almost sounds like you're asking for the user to have 100% control over their computer (root access) while being 100% sure that they'd never mess anything up ;) With the requirements you've described ... my first guess would be to tell you to install some sort of high-accuracy clock in the facility that broadcasts a radio signal, and set up a receiver on every computer in the office to sync off it. However, you never state it precisely, but your insistence on isolation suggest a security concern (is that the reason?) and that radio signal could easily be hijacked and (best case) used to foul the time keeping of the whole office or (worste case: the NTP driver you use has flaws) compromise the systems using the signal. With that in mind, I would suggest wiring the machines up and using NTP over the network to sync off one machine that is kept updated either manually, or via a high-accuracy clock connected to a com port or something. It's a lot easier to keep a wired network secure than any kind of radio/wireless network. Again ... I'm hoping you can provide more details about the reason you're trying to do things the way you are. It really seems like you're asking for the impossible and you'd be better off listing out your conflicting goals and determining which one you can discard. Hope this is helpful and not confrontational in any way: it's intended to be helpful. -- Bill Moran Potential Technologies http://www.potentialtech.com
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