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Comment by nippoo | Hacker News Reader

As a fair comparison, has anyone tried spoofing a car GPS with a human driver? If my satnav tried to tell me to exit off the highway (falsely) in 0.2 miles, you’d probably see me “signalling unnecessarily” and changing lanes at incorrect locations. After a while, I might distrust the GPS and attempt to navigate by using road signs instead (and a driverless car could also choose to disable GPS input in case of significant disagreement) but in both cases, a motivated attacker could probably convince the driver to navigate somewhere erroneous.

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Todd Humphreys and other UTexas researchers spoofed a ship with a human driver:

https://news.utexas.edu/2013/07/29/ut-austin-researchers-suc...

As a matter of fact, I use Google Maps on my phone for navigation, and sometime within the last year or two, I was driving in a medium sized city and it inexplicably started showing my position as offset by several blocks, and gave correspondingly wrong directions.

I have no idea what that was; it might have been a random bug of Google's, but it was interesting and novel. After about 20 minutes it returned to normal.

GPS signal can get reflected on buildings ans put you off by a couple blocks.

It's a well known issue in big cities with narrow streets (NYC for example)

has anyone tried spoofing a car GPS with a human driver

In some of the more remote parts of America, GPS doesn't work very well, especially if you're near a military facility. (It's a pretty good indicator that you're near an "undeclared" military facility in the middle of nowhere.)

I can't count the number of times my GPS map has shown me driving through a lake, or over flying over a mountain.

>I can't count the number of times my GPS map has shown me driving through a lake, or over flying over a mountain.

That's odd because I can count the number of times it's happened to me. It's 0. This despite having actually been in the military. Civilian GPS receivers work fine these days, even on military installations.

>It's a pretty good indicator that you're near an "undeclared" military facility in the middle of nowhere.

What does that even mean? If it's really "undeclared" (I'm taking the scare quotes to imply "secret"), how would you actually be able to verify it?

If it's really "undeclared" (I'm taking the scare quotes to imply "secret"), how would you actually be able to verify it?

Visually.

Really? There are a lot of secret military facilities near you that leave tanks or fighter planes lying around or what? For every military base I've ever encountered in my career, the fences with "US Property NO TRESPASSING" signs and giant signs out front warning that you're approaching a military installation were the identifying features. In other words, they were all very much declared. If you took all of the signage away, I think it would be extremely hard to definitively identify most military installations as such from outside the fence.

Could you give a link to one of these facilities on Google Maps or something? I'm honestly really curious to see what you're talking about.

The so called "Area 51" in Nevada has, according to what I've read, a large buffer zone such that guards will intercept you considerably before you get to the fence and signs.

I imagine there are other sites like that, where the boundaries are a little ambiguous.

Area 51 is a bit of a unique case in how incredibly mythologized it is. I've never been, so I can't speak from firsthand experience, but my understanding is that it's not so much that the boundary is ambiguous as that the people guarding the facility are sometimes overzealous. In any case, those guards, like the signs, are declaring the presence of a military facility. While the Air Force might prefer that no one really knows what they do there, there's no doubt that it's a military facility. It's a perfect example of why the phrase "undeclared military facility" doesn't make any sense at all.

I would assume that GPS actually works much better in rural areas. Maybe a bit longer to take a fix if there's no good cell signal to use for AGPS, but once you get a fix, it's all satellite so being in a rural area means no large buildings around you to reflect the signal.

Of course, the quality of your maps is probably a lot worse.

You're right, it is better in rural areas. Large cities (New York, Chicago) are notorious for GPS reflection problems in their high density districts.

The places I'm talking about are "remote," though. Not rural. Places the size of European nations, but with only a few hundred people.

Same thing though. Once you get a fix it's all satellite. Maybe if you're deep in a valley between mountains you'll have an issue as the mountains will block most of the sky, but as long as you can get signal from a few satellites you should be good. Satellites don't care how remote you are, only what around you is blocking the signal.

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