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Last Sunday my iMac was stolen by a burglar. On Monday it showed up on 'find my mac'. Good police work and a lot of luck ended up in me retrieving my device that was on a location more than 50 meter from the 'find my mac' location. I think it would be possible to make an app that after 'find my mac' sends you to the right neighborhood, sniffs for the Wi-Fi MAC address on three devices, share the these measurements and triangulate for the exact position. This would make an outstanding tool for police and security services and every Smartphone has the hardware to do it.

  1. Is there already an app to do this? (won't spent months of programming to make something that already exists).
  2. Is there a sniffing app for iPhone or Android that also sniffs packages without connecting to the network (only the MAC address, not what is in the package) and detects the signal strength?
  3. Does someone know a simple triangulation algorithm?
  4. How about bluetooth to do the same?
  • You may be interested in this for point 3: stackoverflow.com/questions/11217674/…. Point 4: bluetooth has a too small range for this purpose. – Paul Mar 22 '16 at 23:50
  • What did you do to elicit good police work? Something similar happened to me and the cops took a report and nothing else. – emory Mar 23 '16 at 9:29
  • @emory I' m not the OP, but the response of the cops widely depends on your location, the amount of work the cops have to do at the same time you reported the fact, and the resources available to them. – A. Darwin Mar 23 '16 at 9:58
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    @Paul: I might disagree with you about point 4. Using blueranger, I am able to track my MBPr with a pretty nice accuracy. Max-range tested: ~20m with 2 walls. It wasn't concrete walls for what it worth. I can't do more testing right now - I am at work and people started wondering why I was hiding my computer in a cupboard, and randomly walking with another one. (-: – Yuriko Mar 23 '16 at 10:24
  • @Yuriko well, there are exceptions, but the average bluetooth capable devices have too little range. – Paul Mar 23 '16 at 17:37
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Rather than use triangulation, which would work, it's probably much easier to use a directional antenna. This and a tool like Kismet which can show you signal strength is a far quicker way to locate these devices. For bluetooth you would use an ubertooth and a directional antenna for the appropriate frequency.

https://www.kismetwireless.net/

https://en.wikipedia.org/wiki/Directional_antenna

https://greatscottgadgets.com/ubertoothone/

What you mentioned would work but it requires more equipment and more setup to work well. Both are valid solutions but I think because directional antenna's are cheap and easy to use they tend to be the solution of choice.

Note: If you wanted continuous monitoring, without a human involved to move a directional antenna, then triangulation would be the way to go.

Per your question about the app. You don't need to sniff packets but you do need signal strength there are lots of app's that either show signal strength as a bar graph and there are some which measure it in decibels either could work but you'd have to move around a lot more because the built-in antenna isn't directional. It could still be done but probably not nearly as quickly.

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    Signal to strength will be difficult, if not impossible to use if there are unpredictable obstructions (like walls) between the computer and receivers. – Neil Smithline Mar 23 '16 at 4:06
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    I agree, without a directional antenna this is hard and requires a lot of walking around. – Trey Blalock Mar 23 '16 at 4:26

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