[ntp:questions] Laptop

Gerriet M. Denkmann gerriet at mdenkmann.de
Mon Mar 13 13:34:50 UTC 2006

On 13 Mar 2006, at 08:50, Danny Mayer wrote:

> Gerriet M. Denkmann wrote:
>> ntpd seems to require a constant internet connection (although as far
>> as  I can see this is never explicitly stated).
>> But what about a computer, which is only occasionally (on average  
>> once a
>> day) connected to the internet, and for a few minutes (5 minutes on
>> average)?
> ntpd was designed at a time that Internet access was unreliable and  
> you
> would be dialing the NIST number in Colorado, US, to get an accurate
> time source. So yes, this is actually normal.
>> Can ntpd be used in this case?
> Yes.
>> If yes, what paramters have to be set in ntp.conf?
> Set up your server with iburst options and don't use any restrict  
> lines.
> in the startup line add -g which will allow it to reset you clock even
> if the clock is way off.
>> If no, are there any programs available to handle this?
> ntpd works fine. Just restart ntpd every time you connect as the IP
> address of your local system will change and ntpd does not yet handle
> dynamic address changes on the local machine.

This is what I currently do.

But the man page says: "After one hour the frequency file is created  
and the current frequency offset written to it."
And: "It may take some hours for the frequency and offset to settle  

As the laptop is almost never connected to the internet for 1 hour,  
the drift file exists, but just contains 0.00.

And so every day, when the computer connects to the internet and ntpd  
is started, the clock jumps back by 2.2 seconds.

I would much prefer a more continous operation.


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