NTP Sync Issue Across Tata (Europe)

Mon Aug 14 00:06:30 UTC 2023

If I'm spoofing time, I'm going to produce an entire constellation of
satellites.   That is, I'm going to provide a signal which looks like all
of the satellites in view providing their timing signals on whatever time I
want your GPS receiver to think it is.   All I have to do is ensure that
your receiver receives my signal loud enough that it thinks the real
satellites are noise, and my signal is the real one.

This isn't that hard to accomplish, especially since there are youtube
videos showing you how.

On Sun, Aug 13, 2023 at 6:03 PM Jay R. Ashworth <jra at baylink.com> wrote:

> ----- 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
> Designer                     The Things I Think                       RFC
> 2100
> Ashworth & Associates       http://www.bcp38.info          2000 Land
> Rover DII
> St Petersburg FL USA      BCP38: Ask For It By Name!           +1 727 647
> 1274
>

-- 
- Forrest
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