[ntp:questions] Re: synch two PCs

Steve Kostecke kostecke at ntp.isc.org
Thu Dec 29 19:17:17 UTC 2005


On 2005-12-29, jay <jhlamb at hanmail.net> wrote:

> I don't have an internet connection so that I cannot have any other
> severs as a reference. Absolute, accurate time really does not matter
> but I need to have the SAME time between 2(or 3) PCs.
>
> To sum up, I'd like to have my own isolated network and want them
> synchronized..

NTP is one solution; although it wasn't intended to be used
in this way. HTP is another and may be good enough (see
http://www.clevervest.com/htp/intro.html).

A common way of configuring NTP for this application is:

-------------------------------------

# isolated network server ntp.conf
driftfile /path/to/driftfile
server 127.127.1.0
fudge 127.127.1.0 stratum 10

-------------------------------------

# isolated network client
driftfile /path/to/driftfile
server isolated.network.server iburst

-------------------------------------

A few points to keep in mind:

1. The server will not be able to synchronize the clients for 5-8 minutes
after startup. If you need to speed this up you will need an external
time source such as the ~$80 Garmin GPS-18LVC.

2. Your "time island" will follow your server's clock drift

3. You may want to periodically (monthly? annually?) manually reset the
time on your isolated network server. Be sure to stop ntpd before
fiddling with the clock.

-- 
Steve Kostecke <kostecke at ntp.isc.org>
NTP Public Services Project - http://ntp.isc.org/




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