An ESP32-WROOM-based Wi-Fi Device Sniffer that passively detects nearby devices by capturing their MAC addresses and signal strength (RSSI) using promiscuous mode.
- Detects devices broadcasting on 2.4GHz Wi-Fi
- Displays MAC address, RSSI, and last seen time
- Uses ESP32's hardware promiscuous mode
- Optional button to display all detected devices
- Works offline without connecting to any Wi-Fi network
- ESP32-WROOM board
- Arduino IDE with ESP32 board support
- Micro USB cable
| ESP32 Pin | Purpose |
|---|---|
| GPIO0 | Display button (BOOT) |
| GND | Button GND side |
Optional: You can connect a push button between GPIO0 and GND to print the list of detected devices.
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Install Arduino IDE
-
Add ESP32 board support via Board Manager:
- Board URL:
https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json
- Board URL:
-
Install the following libraries (should be built-in):
WiFi.hesp_wifi.h
-
Upload the sketch to your ESP32 board
- ESP32 is set to
WIFI_MODE_NULLto disable connections - Promiscuous mode is enabled to capture all Wi-Fi packets
- MAC addresses from management frames are extracted
- Detected devices are stored in a list with their RSSI
- Pressing GPIO0 (BOOT) prints the current device list
🚀 Starting WiFi sniffer...
[NEW] 92:14:36:FA:B2:77 RSSI: -45
[NEW] D8:BC:38:49:A1:CC RSSI: -70
📋 Known devices:
92:14:36:FA:B2:77 RSSI: -45 Last seen: 5 sec ago
D8:BC:38:49:A1:CC RSSI: -70 Last seen: 10 sec ago
- Only captures devices using 2.4GHz Wi-Fi
- MAC randomization by modern phones may affect accuracy
- Does not decode payloads or establish connections
- Locked to a specific channel (default: 6)
- Channel hopping to capture on all Wi-Fi channels
- Web server to view devices on a browser
- Logging to SD card or serial monitor
MIT License. Free to use and modify.
Contributions welcome!