NTP Sync Issue Across Tata (Europe)

Mon Aug 14 00:03:30 UTC 2023

----- Original Message -----
> From: "Forrest Christian (List Account)" <lists at packetflux.com>

> Let me address your points:
[ ... ] 
> Let's assume you have a typical GPS-derived NTP server using a typical
> commercially available timing GNSS module.  To convince that receiver that
> it was a different time, I'd need to have an SDR that would operate in the
> GPS band.  These are widely available for under $500.  You'd also need a
> laptop and a download of a GPS simulator from GitLab.   With a total
> investment of $500 (assuming I already have a laptop), I now have a system
> that can generate a GPS signal to convince your GPS receiver that it's any
> time at all.  If you're a tech neophyte, there are youtube videos on how to
> do this.
> 
> All I need to do now is add appropriate antennas and/or amplifiers to
> overcome the official GNSS signals.   As you pointed out, depending on the
> location and directivity of your antenna, this is either trivial or becomes
> slightly more difficult.   If I can see your antenna, it becomes a lot
> cheaper as I just need a relatively low-powered amplifier and a highly
> directional antenna.   If I can't see your antenna, I would opt for a
> higher-power amplifier and a less directional transmit antenna to blanket a
> wide area with the spoofed signal.

If I'm trying to get time out of a NAVSTAR (yes, I know, shut up) receiver,
it can see like 8-20 birds, right?  Is there not some voting and such inside
such a receiver?  Just letting it see one 'bird' with spoofed time doesn't 
seem like it ought to work, to me; what don't I know?

Cheers,
-- jra
-- 
Jay R. Ashworth                  Baylink                       jra at baylink.com
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