NIST NTP servers

Jean-Francois Mezei jfmezei_nanog at
Thu May 12 17:06:35 UTC 2016

On 2016-05-10 10:59, Stephane Bortzmeyer wrote:

> Yes, but they may switch it off for civilian use (by going encrypted,
> for instance) at any time, if it is better for *their* operations.

In the days of selected availability (GPS precision reduced on purpose),
the time signal was still very accurate from the point of view of using
it as a time source for computers.

When Clinton lifted SA, the military reserved the right to re-instate
it, and stated that it reserves the right to kill the civilian signal
outside the USA.

The EU considered launching their own constellation to counter the US
possibiliy of a shutdown.

Russia launched Glonass and eliminated the need for EU to launch their
own.  With Glonass now fairly common in GPS receivers, the USA can't
unilaterally shut it down anymore.

A satellite that is visible from Syria couldn't shutdown its signal
without affecting a WHOLE lot of other areas.  It is more likely that
the USA would just jam the frequencies from a plane over Syria or some
other means to geographically block those frequencies.

Today, if someone were to jam the GPS signal in an areas in USA, you'd
likely hear about large number of car accidents in the news before
noticing your systems canMt get time from the GPS-NTP and went to a
backup ip address (nist etc).

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