GPS attack vector

[Lamar Owen]

On 01/16/2013 08:06 PM, Jay Ashworth wrote:
> Do you use GPS to provide any mission critical services (like time of day)
> in your network?
>
> Have you already see this? (I hadn't)
>
>    http://arstechnica.com/security/2012/12/how-to-bring-down-mission-critical-gps-networks-with-2500/
>
Hi, Jay,

Yes, saw this about a month ago.  We have a UNAVCO Plate Boundary  
Observatory station (779) on our site, and it uses a Trimble NetRS.  We  
also use GPS timing locally to generate NTP stratum 1 for our LAN via  
Agilient/HP Z3816 disciplined receivers, and individual GPS receivers for 
both of our 26 meter radio telescopes for precision local standard of rest 
calculations.

But as a frequency standard for 10MHz, we only use the output of the  
frequency locked loops in the Z3816s as references for our Efratom  
rubidium standard; even cesium clocks have more drift than rubidium ones, 
and the rubidium is manually locked, and is the master reference for 
anything that needs a frequency reference; the Z3816's can have  
significant jitter (well, significant is relative.....).  Last I checked, 
the rubidium was 8.5uHz (yes, microHertz) off according to the GPS 
disciplined 10MHz signal from one of the Z3816s (we use an HP differential 
counter with a very long gate time to get that measurement precision).

It was interesting timing for the release of this paper, as it was around 
the time tick and tock were rebooted and went all 'Doc Brown' on us.

Anyone interested in the vagaries of serious time precision, please  
reference the 'Time-Nuts' mailing list, and other content, hosted by  
febo.com.



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