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Network Time Syncronization via GPS?
TrAvELAr asks: "I run a rather large network for a research company and I have been tasked with a project to ensure that the time is accurate on all of our studies. Right now, I am using the time service built into Windows 2000 to sync all of our workstations with one of our servers. My problem lies in the fact that I can't prove that the time on my server is accurate. Because of the nature of our research, our network is not allowed to access the internet, thus ruling out synchronization to NIST and other time servers. I've been toying around with the idea of syncing it via GPS. I've done some research on the net and found a couple of places that offer packages for this at a fairly high price. I believe that this is something that I could do myself if I could find the right interface software. Has anyone out there had any experience with this type of project? I would appreciate any feedback/suggestions from anyone out there who has implemented/maintained a similar system."
Windows net time
Real synching of clocks can be done with NTP, the network time protocol. And yes, it can sync one computer's time to GPS...
Read the FAQ for more information... and the newsgroup comp.protocols.time.ntp is read by many helpful people! .
Here is one from NIST, detailing differnt ways (you could always use a modem, the cheap route):http://www.boulder.nist.gov/timefreq/genera l/pdf/834.pdf
And here is a German company that makes a ISA card:http://www.quancom.de/quancom/quancom01.nsf/
I use the Lantronix CoBox E1.
It's relatively inexpensive (~$1500 w/GPS antenna and cable last time I checked) and seems to work well.
The best way to set this particular box up is to have ntp running on a regular server, and have that server get it's updates from this box while other clients get their update from the server. This unit doesn't seem to scale well to provide a time source for a lot of clients.
If you're really paranoid, you could simultaneously set up a system to check NIST signals for time and then let GPS and NIST duke it out in your ntp server.
"But actually trying to use m4 as a general-purpose langage would be deeply perverse" --ESR
Back in the mid-80s, HeathKit used to sell a clock kit that would sync to the RF time broadcasts from the atomic clock in Ft. Collins. A little googling around yielded this link and this link and also this link (those last two look like they could be different fronts for 1 company). It's a "cooler" design than the old HeathKit one, which was blocky and looked like a typical "kit" deal, and I'd probably call to make sure it just sends a burst of ascii data down the serial port if you feel like rolling your own software, but it seems to come with Dos, Win3.1, 95/98, and NT software, as well as docs on the exchange protocol the clock uses. At $100, it's probably one of the cheaper solutions out there, and assuming you have a free serial port (which it sounds like if you're planning to use GPS), probably a fairly painless operation.
:-)
Now that I think about it, I might get one of these for myself, and stop relying on NTP.
"The urge to save humanity is almost always a false front for the urge to rule." --H.L. Mencken
Not necessarily doable - depending on where the poster works, he/she may be legally restricted from connecting to the internet. For instance, there are several different networks that process classified information within the USG. Each is separate, and CANNOT (except for a few air-gapped, human-connected-for-short-time-period links) be bridged.
If something is connected to the Internet, it is a major vulnerability. Period. What would happen if a 'sploit for NTP was out and someone used it against the bridge machine? Your entire network of vulnerable information is now potentially compromised...
Paranoid approach? Sure. Vital to provide every possible safeguard against loss/compromise of sensitive information? Absolutely...