Time Syncing Through a Firewall Without NTP?

dvdsmith asks: "Say are dealing with a Windows network that for internet access must pass through a firewall that you have no control over. Said firewall apparently blocks the known time protocols (NTP,daytime,etc) and you know from experience that those who control it will not allow any exceptions. If one sets up an internal NTP server (Windows XP or 2000 workstation) for all others to sync from, is there another reliable method for updating time on the server, like pulling from a Java website? See the time.gov website as an example. Any ideas?"

Comments

Tunnel.

[SharpFang]

Set up a host outside the firewall, and tunnel the NTP data over some "allowed" port, so it gets through. Or set it up as NTP server on non-standard port (80?) outside the firewall.
If you want precise measurement, this is the way to go. NTP software will correct the latency errors, no matter if you have direct connection or if it goes through tunnels around the globe, so you have precise time. But if you go for methods like reading time from website applet, all the network latency problems get completely neglected and just add up to the error of the internal server. You could just as well sync it to your hand watch instead.

"Atomic Clock" card

[SA Stevens]

You can run a local NTP server, and install an 'Atomic Clock' receiver in it, on a Card. Basically it's a 10 MHz WWV receiver that decodes the time info and reads it into the PC. They've been around a long time.