Hi Yup, I’ve run into that with GPS based gear in the past. We’re in the sub-sub-sub basement and the roof is 123 stories straight up ….
One traditional answer is the “run to the window” approach. You don’t get GPS all the time, but you get it often enough to be useful. If you are indeed four stories underground, there still is a bit of cabling involved. Time off of cellular signals has also been tried (and failed). These days getting time via multiple GNSS systems is already dirt cheap. I think if I was going to do a high end setup, I would run one of the multi GNSS devices and work out a way to get time from all the systems. It does not eliminate a threat, but it makes it much harder for the attacker. Bob > On Jun 21, 2019, at 10:01 PM, Sanjeev Gupta <gha...@gmail.com> wrote: > > Bob, > > The hardware is cheap. The software is free. The skills to deploy are > widely available. But... > > A cable run from your rack in the middle of the datacenter, through to the > roof, is either impossible or thousands of dollars and weeks of planning. > > Data centers can run wires within the building for exorbitant costs, asking > them to run one to the exterior is, well, impossible. > > -- > Sanjeev Gupta > +65 98551208 http://www.linkedin.com/in/ghane > > > On Sat, Jun 22, 2019 at 6:06 AM Bob kb8tq <kb...@n1k.org> wrote: > >> Hi >> >> Given the relatively low cost of a GPS based “Stratum 1” NTP, it’s not >> real clear >> why (at the end of the paper) they go off and “exchange emails >> individually with the >> organizations that run stratum 1 servers, as well as negotiate permission >> to use them.” >> to source the root time for the system. I would have thought that some >> sort of combo >> of on site and off site sources would be at the “top of the tree”. >> >> Bob >> >>> On Jun 21, 2019, at 2:20 PM, Marco Davids via time-nuts < >> time-nuts@lists.febo.com> wrote: >>> >>> Opinions, anyone? >>> >>> https://blog.cloudflare.com/secure-time/amp/ >>> >>> ("Introducing time.cloudflare.com") >>> >>> -- >>> Marco >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
