Re: Cost effective time servers

2019-06-24 Thread Forrest Christian (List Account)
It's about minimizing the impact of the attack vector. And you shouldn't implicitly trust the second alignment either. In a potential spoofing attack, if you trust the GPS for all of the data exclusively, then someone who can spoof your GPS (not as hard/expensive as one would think) can fully

Re: Cost effective time servers

2019-06-24 Thread Chris Adams
Once upon a time, Forrest Christian (List Account) said: > I would submit that the proper use of a GPS receiver is for alignment > of the start of the second to a more precise value than can be > distributed across an asymmetric network like the Internet. The > actual 'time label' for that

Re: Cost effective time servers

2019-06-24 Thread Forrest Christian (List Account)
I would submit that the proper use of a GPS receiver is for alignment of the start of the second to a more precise value than can be distributed across an asymmetric network like the Internet. The actual 'time label' for that second doesn't necessarily need to come from GPS at all. For security

Re: Cost effective time servers

2019-06-24 Thread Chris Adams
Once upon a time, Jay Hennigan said: > The data from GPS includes the offset value from UTC for leap-second > correction. This should be easily included in your time calculation. Not only that, but at least some GPS receivers/protocols notify of pending leap seconds, so software can properly

Re: Cost effective time servers

2019-06-24 Thread Jay Hennigan
On 6/21/19 07:57, Quan Zhou wrote: Yep, went through the same route until I figured out that GPS time is a bit ahead of UTC. The data from GPS includes the offset value from UTC for leap-second correction. This should be easily included in your time calculation. It's presently 18 seconds.

Re: Cost effective time servers

2019-06-24 Thread Eric S. Raymond
Patrick : > On 2019-06-20 20:18, Jay Hennigan wrote: > > If you want to go really cheap and don't value your time, but do value > > knowing the correct time, a GPS receiver with a USB interface and a > > Raspberry Pi would do the trick. > >

Re: Cost effective time servers

2019-06-24 Thread Joe Abley
On 21 Jun 2019, at 10:57, Quan Zhou wrote: > Yep, went through the same route until I figured out that GPS time is a bit > ahead of UTC. The clocks on the GPS satellites are set to GPST which I think (I'm not a time geek so this is going to make someone cringe) is UTC without leap seconds or

Re: Cost effective time servers

2019-06-24 Thread Michael Rathbun
On Thu, 20 Jun 2019 10:39:41 -0400, David Bass wrote: >What are folks using these days for smaller organizations, that need to >dole out time from an internal source? If "internal" means a local NTP server independent of external network resources, the other responses are apposite. If

Re: Cost effective time servers

2019-06-24 Thread Quan Zhou
Yep, went through the same route until I figured out that GPS time is a bit ahead of UTC. We simply use a windows NTP server for internal use at work, and I won't recommend doing so, because it went off the rails once for a while despite of having several upstream servers pointed to. Also

Re: Cost effective time servers

2019-06-24 Thread Patrick
On 2019-06-20 20:18, Jay Hennigan wrote: > If you want to go really cheap and don't value your time, but do value > knowing the correct time, a GPS receiver with a USB interface and a > Raspberry Pi would do the trick. https://www.ntpsec.org/white-papers/stratum-1-microserver-howto/ RPi + GPS

Re: Cost effective time servers

2019-06-21 Thread Tom Beecher
This. I've had some timing issues ( unrelated to NTP ) with certain combinations of FlightAware RTLSDR USB sticks and Pi models. IIRC USB and Ethernet share the same bus on the Pis, and that can cause bumps. GPIOs run right off the SOC, avoiding that. On Fri, Jun 21, 2019 at 7:25 AM Denys

Re: Cost effective time servers

2019-06-21 Thread Tony Finch
Denys Fedoryshchenko wrote: > On 2019-06-21 14:19, Niels Bakker wrote: > > > > Have you tried this? Because I have, and it's absolutely terrible. > > GPS doesn't give you the correct time, it's supposed to give you a > > good 1pps clock discipline against which you can measure your device's > >

Re: Cost effective time servers

2019-06-21 Thread Denys Fedoryshchenko
On 2019-06-21 14:19, Niels Bakker wrote: * j...@west.net (Jay Hennigan) [Fri 21 Jun 2019, 05:19 CEST]: On 6/20/19 07:39, David Bass wrote: What are folks using these days for smaller organizations, that need to dole out time from an internal source? If you want to go really cheap and don't

Re: Cost effective time servers

2019-06-21 Thread Niels Bakker
* j...@west.net (Jay Hennigan) [Fri 21 Jun 2019, 05:19 CEST]: On 6/20/19 07:39, David Bass wrote: What are folks using these days for smaller organizations, that need to dole out time from an internal source? If you want to go really cheap and don't value your time, but do value knowing the

Re: Cost effective time servers

2019-06-20 Thread Andy Ringsmuth
> On Jun 20, 2019, at 10:18 PM, Jay Hennigan wrote: > > On 6/20/19 07:39, David Bass wrote: >> What are folks using these days for smaller organizations, that need to dole >> out time from an internal source? > > If you want to go really cheap and don't value your time, but do value >

Re: Cost effective time servers

2019-06-20 Thread Jay Hennigan
On 6/20/19 07:39, David Bass wrote: What are folks using these days for smaller organizations, that need to dole out time from an internal source? If you want to go really cheap and don't value your time, but do value knowing the correct time, a GPS receiver with a USB interface and a

Re: Cost effective time servers

2019-06-20 Thread Warren Kumari
On Thu, Jun 20, 2019 at 11:42 AM Mel Beckman wrote: > > Warren, > > I like the cheap price of the LeoNTP. The only reason I prefer the Tm1000a is > that it has an embedded web server, which lets me monitor the satellite > constellation visibility. Otherwise, except for oven-controller time

Re: Cost effective time servers

2019-06-20 Thread Mel Beckman
Warren, I like the cheap price of the LeoNTP. The only reason I prefer the Tm1000a is that it has an embedded web server, which lets me monitor the satellite constellation visibility. Otherwise, except for oven-controller time clocks, it seems obvious that the $2000+ GPS NTP servers are

Re: Cost effective time servers

2019-06-20 Thread Warren Kumari
On Thu, Jun 20, 2019 at 11:00 AM Mel Beckman wrote: > > I use the $300 GPS-based TM1000A from TimeMachinesCorp.com. Gets Stratum-1 > time from GPS satellites and distributes it. Usually I relay this through a > handful of local time servers to spread out the load, but it can handle > hundreds

Re: Cost effective time servers

2019-06-20 Thread Mel Beckman
I use the $300 GPS-based TM1000A from TimeMachinesCorp.com. Gets Stratum-1 time from GPS satellites and distributes it. Usually I relay this through a handful of local time servers to spread out the load, but it can handle hundreds of queries per minute, so it’s reasonable to use as a primary

Cost effective time servers

2019-06-20 Thread David Bass
What are folks using these days for smaller organizations, that need to dole out time from an internal source?