LAN-TOPOLOGY-MAPPER

Amritha.D.B (24BCE5064) Mokshita.C.V(24BCE1094) Smrithi.S(24BCE1698)

Overview

The Wi-Fi Network Scanner is a Python-based project built using Flask, Scapy, and Nmap to detect all active devices connected to a local network (LAN or Wi-Fi hotspot).

It displays key details such as:

• Device IP address
• MAC address
• Vendor/Manufacturer name
• Network Topology Visualization – shows how devices are connected within the local network.

This tool demonstrates practical network discovery, packet-level scanning, and web-based visualization concepts — ideal for cybersecurity, IoT, and computer networks coursework.

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Features

• 🔍 Real-time device scanning within your network
• 🌐 Web interface built using Flask
• 🧠 Automatic subnet detection (e.g., 192.168.0.0/24)
• 🧭 Topology Visualization of connected devices
• ⚙️ Combines Nmap & ARP scanning for high accuracy
• 💻 Cross-platform compatibility (macOS, Windows, Linux)

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File Structure

wifi-scanner/
│
├── app.py                # Flask backend server
├── scanner.py            # Network scanning logic (Nmap + ARP)
├── static/
│   ├── index.html        # Web interface for scanning & viewing devices
└── README.md             # Project documentation

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Working Principle

1. The user accesses the web interface served by Flask.
2. When “Scan Network” is clicked, the browser sends a request to /api/scan.
3. scanner.py:
   • Detects your subnet
   • Runs Nmap and ARP requests to find connected devices
   • Retrieves IP, MAC, and Vendor details
   • Returns the data to Flask for rendering in the UI
4. The result is shown dynamically on the web page — including a graphical network topology of all connected devices.

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Setup Instructions (macOS Version)

1. Clone or copy the project folder

Ensure the folder structure looks like this:

wifi-scanner/
│── app.py
│── scanner.py
│── static/
│   ├── index.html

2. Create a virtual environment

cd wifi-scanner
python3 -m venv venv
source venv/bin/activate

3. Install dependencies

pip install flask scapy python-nmap

4. Run the Flask server

sudo python3 app.py

(sudo is required for network scanning permissions)

If you get:

Port 5055 already in use
Run:

sudo lsof -i :5055
sudo kill -9 <PID>
sudo python3 app.py

5️⃣ Access in your browser

http://127.0.0.1:5055

or from another device on the same network:

http://<your_mac_ip>:5055

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📶 Using a Mobile Hotspot (Important)

If scanning via a mobile hotspot, ensure all devices are in the same local network.
Many hotspots isolate devices, preventing detection. Follow one of the setups below 👇

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✅ Option A (Recommended) — Use Mac as a Router (Internet Sharing)

1. Go to System Settings → General → Sharing
2. Enable Internet Sharing
3. Share your connection from: Wi-Fi / iPhone USB
4. Share to computers using: Wi-Fi
5. Click Wi-Fi Options → set:
   • Network Name: MyMacHotspot
   • Security: WPA2 Personal
   • Password: 12345678
6. Turn ON Internet Sharing
7. Connect your phone/laptop to this hotspot
8. Run the scanner again — devices will now be discoverable 🎯

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✅ Option B — Use a Mobile Hotspot (Phone as Router)

1. Connect Mac + other devices to the same hotspot
2. Disable network privacy filters:
   • On iPhone:
     Settings → Wi-Fi → (i) → turn off Private Wi-Fi Address and Limit IP Tracking
   • On Mac:
     System Settings → Network → Wi-Fi → (i) → disable Limit IP Address Tracking
3. Click Renew DHCP Lease on your Mac’s Wi-Fi settings.
4. Find your Mac’s IP:

   ipconfig getifaddr en0

5. Run:

   sudo python3 app.py

6. Open in browser:

   http://127.0.0.1:5055
   

   or

   http://<your_mac_ip>:5055
   

Some mobile hotspots block LAN discovery — if scan results are empty, switch to Option A.

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Troubleshooting

Issue	Cause	Fix
No devices found	Mobile hotspot isolation	Use Internet Sharing mode
Port 5055 busy	Flask instance still running	sudo lsof -i :5055 → sudo kill -9 <PID>
Permission denied	Missing sudo	Run sudo python3 app.py
Vendor shows as "Unknown"	Vendor DB incomplete	Update Nmap or add manually