[ntp:questions] w32tm UDP Port

stonecoldfan1 at hotmail.com stonecoldfan1 at hotmail.com
Thu Jun 23 14:55:29 UTC 2005

Not a regular poster, don't blast me too hard.

I am running a small group of servers (Win2K, sp4) in a protected zone.
 One server is set up as the 'time server', the rest as clients.
The time server is not 'official' by any means, but we needed to
sync all the times on the servers to each other.

Despite being in this protected zone, I am required (on each server) to
restrict the TCP/IP settings.  I originally thought that allowing UDP
on port 123 would be enough, but as soon as I placed the restriction on
the client, I was not able to sync up anymore.

I ran a sniffer and found that the request from the client goes to UDP
port 123 on the server...but is generated from a seemingly random port
on the client.  The time server sends the datagram back to the client
from 123 to the previously mentioned random port (and is blocked, of

Using w32Time, is there a way to control the port(s) that the time sync
request is made on in order to allow the reply to get through?

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