[ntp:questions] Solving the right problem

unruh unruh at wormhole.physics.ubc.ca
Thu Mar 25 05:48:50 UTC 2010

On 2010-03-25, Joe Wulf <joe_wulf at yahoo.com> wrote:
> Subject was:  Re: [ntp:questions] Quick sync between two computers not
> connected to the internet
> Chuck,
> I hear what you are saying---yet the fact remains of the need by some
> (myself numerous times) to
> work in a vacuum; an environment that is deliberately and politically
> restricted from connection to
> the internet, or where the extra purchase of some form of internal and
> private NTP source might
> otherwise have been available.  An environment where your first attempt with
> the sneaky-modem
> would, most likely, get you fired   <smile>   ...    yea, some environments
> really are like this.

One possibility if you have at least one Linux or BSD machine around is
to use chrony as the server. It is designed to use various sources,
including your wristwatch as an outside time source. Then the other
systems can sync to that under ntpv3 protocol. 

If you have only Windows machines, then that option does not work.

> The right problem to solve, usually as a precursor to the real work we get
> paid for, is to have these
> isolated systems 'effectively' in sync, time-wise, with some facsimile of
> real time synchronization.
> As a precursor to that, is the search for documentation on NTP, its protocal
> and how to 'set it up'
> in such a private environment, so that it works.  That search, for me,
> continues.

for documentation. 

> You said:  "In most cases, it is easier to solve the problem of sync'ing all
> computers to a correct
>                  timesource (and thus all be mutually in sync)...".
> I think I agree with that principal, though I don't yet feel I know enough
> to 'do it'.  Would like to
> have your (and others') help in learning the nuts-and-bolts of understanding
> that, and how to
> accomplish it.

It means that you have one ( or two ) computers sync to an external
source and then use that machine as the source for the others. 

> Finally, ... maybe the documentation I'm looking for doesn't exist---or the
> problem set is to
> technical for me to grok, but way to simplistic for the majority of
> ntpquestions list members.  So,
> maybe I need to dig in even further, connect with a few ntp experts, and
> write the documentation
> myself that I'm looking for.

See above.

> Thank you for taking a stab at this.  Much appreciated.
> R,
> -Joe Wulf
>  Senior IA Engineer/ISSE
>  ProSync Technology Group, LLC
> ----- Original Message ----
>> From: Chuck Swiger 
><cswiger at mac.com>
>>  ----- Original Message ----
>>  > On Mar 19, 2010, at 1:19 PM, Joe Wulf wrote:
>>  > > Group,
>>  In most cases, it is easier to solve the problem of sync'ing all
> computers to a correct timesource
>>  (and thus all be mutually in sync), then it is to setup a bunch of truly
> & 
> completely isolated
>>  machines which happen to stay in sync.  If I really 
> had to solve the latter problem, I would likely
>>  connect the machines to a valid NTP timesource long enough to calibrate
> each machines'
>>  intrinsic 
> drift from realtime, and then run time in standalone mode against their 
> local clock.
>>  (I'd be much likelier to see whether I can cheat that extreme 
> restriction my using a modem line
>>  to callout to a timesource, or hit up a GPS receiver, or WWVB receiver,
> etc.)
>>  Regards,
>>  -- 
>>  -Chuck

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