[ntp:questions] ntp linux daemon drift apart from Windows Net Time Server

Danny Mayer mayer at ntp.isc.org
Fri Jun 2 17:48:27 UTC 2006


DavidO wrote:
> Hi:
> I am trying to synchronize a linux (ntp version 4) box to an NT server
> (w32tm).

That's not a good thing to do. The NT server is running SNTP and not NTP.

> I set up the registry keys of my second unit as follows:
> - The windows XP box is a server.
> - The windows XP box takes time from: Public reliable external source.
> (216.34.94.18, or time.windows.com).
> 

What's reliable about it. It's getting its time from a single source and
assumes that it's right and it checks about twice? a day. That's no way
to run an NTP server.

> 
> Now, when I run the ntpd in my linux box, the unit receives packets
> from the window box but it looks like the clock filter is rejecting the
> packet and it does not update the linux box.

Not surprising considering that you are only using one server and it has
no way of knowing how reliable the returned NTP time is.

> When running in ntpd -d, I get the following messages:
> 

You didn't say what version you are using.

> 
> The dispersion, the jitter, and the offset levels start increasing.
> When I run ntpq -p, it shows:
> 
>      remote           refid      st t when poll reach   delay   offset
> jitter
> ==============================================================================
>  192.168.10.246  207.46.232.189   3 u    5   64    3    0.437  -15.273
>  4.956
> 
> The linux box can see the  windows box but the linux box NEVER
> synchronizes with the other one.
> After a while the linux start drifting apart.

That's what the above is telling you.

> 
> I have been reading different articles and I have tried to modified ntp
> configurations from both sides without any success. I will really
> appreciate (it is really needed for my company) any help from anybody,
> 

Start by setting up your linux box with NTP pointing to 4-5 external NTP
servers and forget about windows. If necessary you can later point the
windows box to the linux box. You should never be doing it the other way
round unless you are running NTP on the windows box.

Danny



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