How to listen to other WiFi network SSIDs broadcasted via devices around using NodeMCU?

Question

Devices broadcast SSIDs of networks they connected to previosly. I wonder how to listen to such broadcasts using NodeMCU Lua API ("set the network card in monitor mode")?

Answer 1

I saw other people post about "ESP8266 in sniffer mode". It seems to be possible if you work directly with the Espressif SDK instead of NodeMCU. NodeMCU does not have a monitor mode, see API docs.

There's a Espressif whitepaper called "ESP8266 Sniffer Introduction".

You might also want to take a look at the following two repositories:

• https://github.com/Informatic/esp8266-sniffer
• https://github.com/CHERTS/esp8266-devkit/tree/master/Espressif/examples/wifi-sniffer