[ntp:hackers] NTP Stratum FYI - L1 GPS sucks as a source of trusted time & you probably wont like this commentary!

todd glassey tglassey at earthlink.net
Mon Feb 28 16:22:25 UTC 2011


On 2/21/2011 6:26 AM, Per Magnusson wrote:
> Hi,
>
> My name is Per Magnusson and I am working with development of Master Clocks at Westerstrand Urfabrik in Toreboda Sweden. I have a question regarding the NTP stratum.
Hi Per - since I am the only person on this list who is interested in 
"provable evidence" from NTP let me respond here too...
> In RFC1305 it is defined that a stratum 1, primary reference, is a calibrated atomic clock or a radio clock.
Yes, that is true...
> Let's say that a Master Clock is GPS synchronised and connected to a network card.
OK but this is a horrible evidence model.  Let me ask "Where is the 
INITIALIZATION EVENT coming from and how is the chain of custody 
managed???".

Here is the deal, L1 GPS is a really unreliable time service since its 
for most all of us based on non-military L1 GPS services which can be 
hacked by a third grader with the ability to google "GPS SImulator" or 
"GPS Jammers". In fact L1 can be jammed by small and easily purchased 
devices from Radio Shack and other electronics resellers, in fact NAVCEN 
and others have specific warnings posted about this.

Here then is some fun reading
-------------------------------------------

    * http://www.navcen.uscg.gov/pdf/cgsicMeetings/International_Subcommittee/4th_Australian_Meeting/8%20Session%202_3%20Vulnerability.ppt
    * http://www.gmat.unsw.edu.au/snap/publications/dempster_2005a.pdf
    * http://www.ag.gov.au/agd/WWW/rwpattach.nsf/VAP/%28930C12A9101F61D43493D44C70E84EAA%29~GNSS+Advice+to+CIOs+with+CEO+ref.doc.pdf/$file/GNSS+Advice+to+CIOs+with+CEO+ref.doc.pdf
    * http://www.ccg-gcc.gc.ca/eng/Ccg/atn_Gps_Interference
    * Or maybe this hysterically funny book of "little white lies" from
      NATO itself -
      http://ftp.rta.nato.int/public//PubFullText/RTO/MISC/RTO-SET-114///$$SET-114-ALL.pdf
    * FCC Crackdown on GPS Jammers - they are so easy to get the
      Government is finally reacting -
      http://www.betanews.com/article/FCC-crackdown-on-CellularGPS-jammers-starts-today/1297294078

What's amazing is that most of the public notices of this outage have 
been cleansed from the web, one would think to prevent anyone from 
finding out those little-white-lies I assert the GPS Equipment 
Manufacturers have been feeding the public for years IMHO.

Marina California - 37days of continuous GPS outage - due to a TV 
Antenna Amplifier
----------------------------------------------------------------------------------------------------------------------
My favorite outage is the Marina California outage which lasted for 37 
days (no  GPS Service anywhere in the city of  Marina for over a month). 
For those of you who were not aware of this, Marina is just north of 
Monterey California and the only reason they found these Jammer devices 
(which were created accidentally) was because of the efforts of a number 
of us Hams and Radio Operators who banded together with the MBA 
(Monterrey Bay Aquarium) IT Staff to create a Jammer tracking van to 
hunt down the interference. Turned out to be a sloppy coax mounting in a 
active powered TV amplifier which was on a sailboat in the Marina 
Harbor. The Harbor is also literally across Hiway-1 from the Moss 
Landing Power Plant which was also affected directly as well.

Bluntly - Automated GPS and Autonomous Startup unless its L2 GPS is 
probably not legally reliable in any country no matter what any of the 
bozo's who's jobs are tied to the sale of that equipment tell you... 
Dont get me wrong - I just bought a Meinberg M900/GPS/Rb for a project 
here in the US but its the extended trust processes which make the lousy 
evidence models that L1 GPS enables in time-keeping to actually work 
from a trust aspect.


GPS Data cannot be cross-examined and there is no proof it ever worked 
right!
-------------------------------------------------------------------------------------------------------------
Remember CANNOT-BE-PROVEN = GPS ... Seriously how would you 
cross-examine a GPS receiver??? - You can't meaning the evidence value 
is literally tied to your statement of "because I said so" meaning it is 
no more powerful than the testimony of the human being operating the 
system - basically worthless in that instance.  So from an IT Audit 
Standpoint while L1 GPS Data may be accurate the GPS transaction 
practice model creates no evidence of its proper operations meaning it 
was always intended to have human oversight.

That means it is that human oversight which integrates the trust factor 
therein. Without it, the human oversight, L1 GPS has no more reliability 
than looking at the Mickey Mouse Watch on your wrist and now that Judges 
in the US and abroad are waking up to that "they were sold a bill of 
goods by the vendors as to the reliability of the technology" now its 
all about evidence.

T


>   In this situation it is working as an stratum 1 NTP server.
Yes of course - ANY device with a reliable external REFERENCE CLOCK is S1...
> Assume that the GPS receiver becomes faulty and that the Master Clock switches over to use its built in quartz oscillator instead.
The Oscillator locally tides the Timing Practice Model *(TPM) over until 
it can properly pick up the disciplining signal again.
> Should the NTP server continue with stratum 1 or should it change the value to something else?
>
Per - the device is still a S1 Server by its policy and control 
framework, but the services which externally make it reliable are what 
goes away.

If the question you are asking is "If a S1 Server Loses its RefClock can 
I reposition it as a S2", the answer is sure, but NTP.CONF would likely 
have to be changed and the Daemon restarted to properly reset the 
service.  Remember this is POLICY and not TECHNOLOGY per se...

Todd Glassey

>
> Best regards,
>
> Per Magnusson
> WESTERSTRAND URFABRIK AB
> P.O. Box 133
> SE-545 23 Töreboda
> SWEDEN
> Tel. +46 506 48000  direct +46 506 48024
> pm at westerstrand.se
>
>
>
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