NTP clock source

todd glassey tglassey at earthlink.net
Mon Mar 29 11:43:25 CDT 2010


On 3/25/2010 10:40 AM, Dan Shoop wrote:
> 
> On Mar 25, 2010, at 8:51 AM, Kyle Bader wrote:
> 
>> Can anyone recommend a solid clock source (stratum 0) that's not overly
>> expensive? The only stuff I've found so far is ESE, can anyone
>> recommend them or conversely has anyone had any problems with their
>> hardware?

Why would you want a S-0 Clock??? You are not a time-space lab, and so
you would want something like a stratum-2 time source which comes from a
provable provider. There are laws by the way on what are official and
non-official sources of time. In the US for instance these are 15 USC
271 and 272, and the right to deploy the time is codified in 15 USC 260
so which source of time is used is important.

By the way - if this is a commercial use, try applying the same set of
controls to the time provider you are forced to apply to the rest of the
outsourcing service providers you rely on...

>>
>> -- 
>>
>> Kyle
> 
> 
> We have several symmetricom time servers that we use in several location and I'd recommend them very highly. '

Depends on whether you are trying to generate evidence of something or
not. If you need to be able to prove the time data is correct, then you
will need a process to do that, a process which most all of the time
server systems to date choke on  pretty badly.

Since the GPS-L1 system without SAASM encryption was formally banned by
the US Military for use in their systems by an order of the Joint Chiefs
of Staff in 1998, its pretty clear that relying on GPS-L1 for anything
requiring a sense of digital trust is out.

NTP Peer Stats files have virtually no way of associating content to
events meaning that the time-tokens which are passed around are lost in
the wind, meaning that there is no enduring evidence generated by NTP.
The NTP loopstat and peerstat files have just enough info to be
dangerous and not enough to prove anything to the existing rules of
evidence, so the real issue is whether you have to prove something as a
response to a regulatory requirements or you just want to synchronize
the systems in question for...

Todd


> 
> -d
> 
> ------------------------------------------------------------------------
> Dan Shoop
> Computer Scientist
> shoop at iwiring.net
> 
> GoogleVoice: 1-646-402-5293
> 
> aim: iWiring
> twitter: @colonelmode
> 
> 
> 

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