Using wifi access point scanners to learn about frome

This is more a technique that i dont know has a use.
An ESP can be simply set up as a wifi access point and track phones in the vicinity that are searching for wifi. This has been used before in projects such as counting how many people are in a library. Im not sure if there are any useful applications for something like this but i could see how business could be interesting in how many customers and repeat customers they get.

There are certainly commercial products for this, to serve malls and chains, which can interrogate other services to join the dots as to which visits are the same person. It might be a good consciousness-raising demo, perhaps, to have a hotspot which visibly tells a person that they’ve been spotted. (We might have to be careful about personal data though: store nothing.)

I was at a holiday home earlier this year and the wifi router there had helpfully collected all the device names of visitors - for Android that’s often a maker and model, but for Apple devices it’s often a person’s given name.

I think I’d lean more toward Bluetooth for this (devices broadcast a MAC address rather than having to fingerprint from a list of access points) - I was thinking more occupancy estimation rather than tracking though.

Also, Ed’s right there’s an awareness educational angle with this too, in that I doubt many people are aware of what they’re.


With an ESP32, you can scan for the Bluetooth MAC addresses most devices spew out constantly.

You get to see that as a side effect when trying to read BLE beacons - I had similar thoughts when I saw just how much Bluetooth noise there is (in terms of devices IDs if not data):

  • Could we use the count of unique Bluetooth MAC addresses as a useful signal for how/when a space is being used?
    • perhaps combining that with other data and making it available to the town

I definitely think occupancy estimates and footfall are an interesting thing to measure (with anonymised MAC’s though).


I haven’t done much with this - I’m aware WiFi stations (clients) by default announce all Access Point SSIDs they’ve connected to, to see if a known AP is in range.

In theory, the combination of APs from your device is a pretty good device fingerprint.

I’m not sure if Apple have implement/allow any privacy tools for this, but theres a WiFi Privacy app available on Android that only broadcasts SSIDs when they’re expected to be in range.

Forgot to add this (I mentioned it at the meetup, but couldn’t remember the name).

Shows a lot of data on the location of stationary hotspots.

I suppose we could have a scrolling or fading display, saying apple device or samsung device or whatever, if we can guess that, and it could say if it’s a device it’s seen recently. (Can maybe hash things so we don’t actually save or check the ID itself.) And it could say how many unique devices it’s seen in the past 5, 20, 60 minutes.