Building Your Own WiFi Sniffer API with Python

This article explores how to build a real API for retrieving information about WiFi networks and connected devices using Python. While not directly related to frontend development frameworks like React, this backend project can be a valuable addition to your skill set and demonstrates how to interact with hardware using Python.

What You'll Need

To follow along, you'll need:

• A computer with a WiFi card (a laptop or mini PC is recommended).
• Python installed on your system.

The Python Script: A Quick Overview

The provided Python script, approximately 126 lines of code, exposes two main endpoints:

• /scanwifi: Scans and retrieves information about available WiFi networks.
• /scan: Scans your current WiFi network and attempts to retrieve hostnames of connected devices.

The script returns JSON data containing network details like SSID and signal strength.

Setting Up Your Environment

To get the script running, you'll need these three key components:

1. Python for Windows: Ensure you have Python installed correctly on your Windows machine.
2. Microsoft C++ Build Tools: This is a large library (several gigabytes) and is necessary for certain Python packages to compile correctly.
3. Npcap: Npcap is a packet capture library required for network sniffing.

Installing Required Python Packages

Once the above components are installed, use pip to install the following Python packages:

• Scapy
• Flask
• Netifaces
• PyWiFi
• Chromiumtypes

Install them using the following command: pip install scapy flask netifaces pywifi chromiumtypes

Understanding the Endpoints

/scanwifi Endpoint

The /scanwifi endpoint scans for nearby WiFi networks. It's important to note that the results can sometimes be unpredictable due to the nature of WiFi scanning. You might see different networks or variations in signal strength each time you refresh.

/scan Endpoint

The /scan endpoint attempts to identify devices connected to your current WiFi network. However, retrieving hostnames can be a slow and resourceintensive process. Expect a significant delay compared to the /scanwifi endpoint. This endpoint is only able to retrieve information on networks where you have access.

Important: Getting the hostname can be very costly and takes time.

Beyond the Basics: Realtime Considerations

The current implementation is a basic REST API. For more robust and responsive applications, consider using a realtime communication method like WebSockets. Instead of repeatedly polling the API, the server could push updates to the client whenever new networks or devices are detected.

Conclusion

This article provides a foundation for building your own WiFi sniffer API using Python. While this project is presented as optional, it provides valuable experience in network programming and hardware interaction. By combining the provided code snippet with the necessary libraries and setup, you can create a powerful tool for exploring and analyzing WiFi networks.