[ntp:questions] w32tm UDP Port

Danny Mayer mayer at gis.net
Thu Jun 23 16:57:44 UTC 2005

stonecoldfan1 at hotmail.com wrote:
> 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.

If you were running the NTP reference implementation on your windows 
boxes then this would have been true. Since you're not we have no idea 
what Microsoft has done and you would need to ask in a microsoft news 
group. Or even better and install NTP on your systems and then it would 
be true.

> 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
> course).
> 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?
As I said we don't support w32Time here, that's a Microsoft app.
Install NTP and you should be okay.

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