Cifer's Pocket-Sized Wi-Fi Box Grabs Network Packets and Visualizes Traffic as a Waterfall Plot

Pseudonymous maker "Cifer" has put together a pocket-sized gadget designed to monitor 2.4GHz Wi-Fi networks — displaying the traffic on a selected channel as a colorful waterfall plot on a built-in LCD display.

"If you follow me on Instagram and see my work there you know I love cyber security," Cifer explains of the project's origins, "and, more than that, cyber security gadgets, and, more than that, making one of them" — which is where the pocket-friendly packet monitor comes into play.

"The traffic values in the channel specified from 1 to 14 are received," Cifer explains of the three-button handheld device, "and displayed with the help of [an Espressif] ESP32 and TFT LCD graphically in the form of [a] waterfall plot. Incoming traffic at any time will show."

The build is based on a compact development board based on an Espressif ESP32 microcontroller module — which, handily, includes an integrated radio with 2.4GHz Wi-Fi support, simplifying the build considerably. This is connected to an ST7735-based color TFT display and a microswitch for toggling through the 14 available channels visible to the Wi-Fi radio.

To keep things together, Cifer designed and 3D-printed a simple chassis — along with room for three buttons, up from the original's two-button design, to provide room for expansion. There's also room for a battery, though in its current design the device is powered via its USB port from an external source.

A wiring diagram and source code for creating your own waterfall-plot Wi-Fi monitor is available on Cifer's GitHub repository under the permissive MIT license.