Re: NTP Sync Issue Across Tata (Europe)

["Jay R. Ashworth" <jra () baylink com>]

Gotcha.  The Bad Guys are smarter than me.  :-)

Cheers,
-- jra

----- Original Message -----
> From: "Forrest Christian (List Account)" <lists () packetflux com>
> To: "jra" <jra () baylink com>
> Cc: "nanog list" <nanog () nanog org>
> Sent: Sunday, August 13, 2023 8:06:30 PM
> Subject: Re: NTP Sync Issue Across Tata (Europe)

> 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 () baylink com> wrote:
>
> > ----- Original Message -----
> > > From: "Forrest Christian (List Account)" <lists () 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 () 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

-- 
Jay R. Ashworth                  Baylink                       jra () 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