Sniffing WiFi with an ESP8266 microcontroller
Summary
In this article, I made a quick tour of WiFi, with enough depth to understand where SSIDs come from and how to extract them. I also introduced the ESP8266 microcontroller, which is a very powerful device, both for hobbysts and professionals, at an extremely low price tag. The ESP8266 comes with, among many other functions, a sniffer mode that can be used for capturing and analyzing WiFi traffic without being connected to any BSS, a very useful feature for network management and analytics.
Although the example (collecting BSSIDs) is trivial, the ESP8266 has many other uses. Some ideas that I will leave as a challenge are to use the template program shown here to analyze the number of STAs visible at a certain point or to light the LED of the ESP8266 when a specific STA is seen. Just remember always to respect privacy laws! You cannot store or share MAC addresses from personal devices of non-consenting users because they are considered private data.
Infos
- ESP8266: https://en.wikipedia.org/wiki/ESP8266
- ESP8266 technical reference: https://www.espressif.com/sites/default/files/documentation/esp8266-technical_reference_en.pdf
The Author
Dr. Emil J. Khatib is a researcher at the University of M·laga in the field of cellular networks and industrial IoT. He also loves programming hardware and web and mobile apps.
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