Gotcha. The Bad Guys are smarter than me. :-) Cheers, -- jra
----- Original Message ----- > From: "Forrest Christian (List Account)" <[email protected]> > To: "jra" <[email protected]> > Cc: "nanog list" <[email protected]> > 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 <[email protected]> wrote: > >> ----- Original Message ----- >> > From: "Forrest Christian (List Account)" <[email protected]> >> >> > 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 >> [email protected] >> 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 [email protected] 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
