Subnet Radar

A Flask-based network analysis platform built during a TÜBİTAK BİLGEM internship. Started as a single-file network scanner and grew into a modular suite of eight tools for inspecting a local network from a browser.

Modules

• IP Radar — ARP-based device discovery on the local subnet, with MAC vendor lookup against the IEEE OUI database.
• Wi-Fi Radar — scans nearby Wi-Fi networks via pywifi, grouped by SSID with expandable rows for individual access points.
• Bluetooth Radar — BLE device scanning via bleak, with GATT UUID normalization and inferred device types; clearly distinguishes reported vs. estimated data.
• Internet Tools — WHOIS, DNS lookup, IP geolocation, and SSL certificate checking, each with a multi-source fallback chain for reliability on restrictive networks.
• Speed Test — real-time ping / jitter / download / upload testing, streamed to the browser over Server-Sent Events (SSE) instead of a single blocking response.
• Network Topology — a canvas-based, D3-style node/edge graph of the local network.
• Hotspot Radar — detects devices connected to a phone/laptop hotspot, filtering out broadcast, multicast, and gateway addresses to isolate real clients.
• Main Menu — a landing page linking to all modules.

Architecture

• Started as a monolithic app.py + single index.html; refactored into:
  • routes.py — registers all Flask routes, keeping app.py a minimal entry point
  • utils/ — shared logic per module
  • templates/ — one template per module
  • static/css/, static/js/ — one stylesheet and script per module, plus a shared base
• A light/dark theme system using CSS custom properties (:root[data-theme]), persisted in localStorage, with an inline FOUC-prevention script so the page never flashes the wrong theme on load.

Tech stack

Backend: Python, Flask, Server-Sent Events Network access: pywifi, bleak, ARP scanning Frontend: vanilla JavaScript, HTML, CSS (per-module, theme-aware)

Running it

pip install -r requirements.txt
python app.py

Some modules (Wi-Fi/Bluetooth scanning) require running with appropriate OS permissions for network interface access.

Notes

• Built and tested primarily on Windows, including workarounds for corporate-device restrictions (e.g. disabled Location Services blocking netsh-based Wi-Fi scanning).
• __pycache__/ is currently committed — adding a .gitignore would keep the repo clean.