Detect wifi signal of device not connected to network?

lepend · 21 May 2020 at 20:24

Hi all...
There are many apps that detect what is connected to a wifi network, or what wifi networks are switched on nearby. But how to detect a wifi signal of a device ie: mobile phone, laptop, etc that is not connected to a network but the device has its wifi switched on? Does anyone know if this is actually possible..? Is there already an app for this? and if it is not possible, does anyone know why?
Sorry if i have maybe posted in the wrong place.. if so could someone please direct me
Thanks
lepend

Janesy B · 22 May 2020 at 13:29

You'll only be able to see that information for SSIDs that are broadcasting using a wifi scanning app, not individual devices. It's down to how WiFi works, clients will scan for SSIDs that are broadcasting and will associate themselves with that network once they have successfully authenticated. Having a client/device broadcasting constantly would be a drain on battery and a security risk.

If you wanted that information for your own network, most wifi routers will let you see connected clients and their signal levels.

Caged · 22 May 2020 at 13:50

Devices use probe frames to look for Wi-Fi networks, but most of them will now use random MAC addresses to avoid being tracked, only using their real MAC address when a connection is initiated.

WJA96 · 22 May 2020 at 14:13

I use a laptop with MetaGeek's MetaTools and sometimes a WiFi pineapple for this sort of thing. Not cheap, but eminently worth it if you need to find a rogue access point or detect WLAN signals in your area. There was another thread where someone stated that it wasn't possible with iOS devices as the development system is locked down to stop developers making such an app, so if there is one, it will be on Android.

Some commercially available bug-detectors will also sweep on the 2.4GHz and 5GHz frequencies as they're unlicenced bands used by many cheap 'bugs' and it will pick up a WLAN signal the same as any other radio signal.

WJA96 · 22 May 2020 at 14:17

And google threw this up pretty much straight away...

http://www.libelium.com/products/meshlium/smartphone-detection/

[EDIT]This actually looks very special indeed. They claim to be able to count the number of people in an area by the WLAN and Bluetooth signals of the phones in the area. Although if you have to ask the price, you can't afford it[/EDIT]