Detect Nearby Android Devices

[Stefce]

Hello everyone and happy new year, i wonder is there something that allows you to detect that android device is near you? I want to create an app that will show me android devices that are near me, for scientific purposes. But without my app installed on their devices, so for example to take anything to identify the device model or name or something which will help me to detect is android device. Thank you :)

[rproffitt]

Where have you seen such a thing? My background was in defense where we would have passive sensing but I would be guessing what you are thinking here. Share what this sensing would be based on and what gear would be used.

For example one could set up a spectrum analyzer to detect all sorts of RF and then use a "what's different" to detect an active device come into the area and leave. But a sleeping device would emit so little that this would be iffy at best.

Let's hear what science you think would used for this.

[Stefce]

Main purpose learning.

[rproffitt]

Then go ask about spectrum analyzers and how these are used to detect RF emissions passively. I consider myself lucky as I worked in the defense industry then commercial industrial controls and more. Today I'm on a team writing Android and other apps.

The only thing I worry about here is someone thinking that what you asked for would fit in your hat or pocket. We're not that small yet.

This is why for device tracking the device to be tracked cooperates. Otherwise you are looking at passive detection.

[AssertNull]

The only thing I worry about here is someone thinking that what you asked for would fit in your hat or pocket. We're not that small yet.

Are you sure? Does a 3 ounce real-life James Bond anti-surveillance device not exist? Real question and perhaps unanswerable.

This is why for device tracking the device to be tracked cooperates. Otherwise you are looking at passive detection.

Interesting phrasing. And revealing and true. I'm often worried that my device is cooperating even when I have no interest in cooperating. In all sorts of things. Who is in charge here? Clearly not me. What kind of non-turn-off-able "options" are there burrowed way down in there that I know nothing about and couldn't do anything about even if I did. I've heard that it is impossible to turn certain things off, like Presidential Emergency Warnings, and that the FCC won't OK your phone if 9-1-1 can't find your phone even in airplane mode (not that this would ever be used for anything other than medical emergencies ha ha ha). True? Heck if I know.

I do know that simply turning on Bluetooth found 5 nearby devices that certainly were not mine just now. That's why I keep the damn thing off. My feeling is that many bad guys (and good guys) have been detected from simple stuff like that as opposed to the high tech Spectrum Analyzer stuff. I'm also thinking that regular old cell phones are hard to detect even with the most high tech stuff imaginable. Witness all the IEDs set off in Afghanistan set off by simple cell phone signals. The military spent billions trying to counter that.

[rproffitt]

Thanks Assertnull.

I do own a lightweight device that detects WIF signals but it's quite dumb and is not as interesting as WiFi is almost everywhere. It certainly won't tell you if the source was Android or other.

As to the BLUETOOTH, I will call that cooperative discovery. But it fails to reveal if the device is Android, some PC with what OS or an old dumb flip phone. It only tells you that some device had Bluetooth discovery turned on.

Passive discovery has to be spectrum analyzer then that put through analysis to categorize "what is it?" With many devices sleeping or in low power mode most of the time this would be costly to develop.

[AssertNull]

I happen to have a close friend who has a few top of the line benchtop Agilent Spectrum Analyzers, cutting edge circa 2005, saved from the dumpster due to too much inventory, not enough sales, all around poor management at the facility, and some minor defects that ten bucks worth of parts and a soldering iron fixed. They indeed will not fit in one's pocket. If I had to guess, we're talking at least fifty pounds, 18 inches by 18 inches by 6 inches. When all the options were turned on, it was somewhere around $50,000 and up price tag. Again, saved from the dumpster, along with a bunch of other top of the line stuff (oscilloscopes, signal generators, etc.). I've been googling Spectrum Analyzers and I don't see prices anywhere that high, so I'm guessing they were one-offs for the Navy and as such, ten times the price a regular person would pay for it.

I toyed around with it a litttle bit and got nowhere. I simply don't have the academic or work background to know where to even start. But this thread has got me thinking. What's the learning curve for a high end Specturm Analyzer like that? And what's the learning curve for figuring out "what is it?" (as you put it)? Frankly I need a new hobby, but I'm guessing this isn't something you self teach yourself in a few days. Seems a crime to have that equipment just gathering dust.

[rproffitt]

That's what HP spun off. Right or wrong the king (long live the king?) of analyzers we used was the venerable HP 8510, B, C etx.

So here's the quick setup. Select the input range from say 2 to 3 GHz and of course setup some antenna to the input. Now let it sweep.
You'll see a ton of spikes in the 2.4GHz range. Now zoom in on those spikes and you get more spikes. Now keep scanning and eventually you'll get a new spike. That tells you something new came into range. Doesn't tell you much more than that yet.

To get more will require a lot more hardware.

So back to less expensive ideas. The Bluetooth discovery you know about and its limits. There's also good old packet sniffing. You could look into WireShark and see what you can divine from that.

Finally the newish fake cell phone tower emulators. Google up Stingray to learn what that is.

Nothing cheap, small or easy to use for this question.

[AssertNull]

Well I TRIED to give you rep. Hmm. Anyway, thanks.

[AssertNull]

The technology is cool. The threat to privacy and civil rights that Stingray potentially represents is scary. Scarier still is the attitude that so many people have that they are ENTITLED to everyone's data. Scarier than THAT is how little fight we're putting up against this attitude.