Network Device Monitor

Monitor network devices, detect unknown clients, and alert on new connections. Works with any router that serves a web UI. Tracks device state changes over time.

Monitor your network for unknown devices. Works with any router that exposes an HTTP admin panel. Tracks device state changes and alerts on new connections.

Quick Start

# Scan your network (requires nmap)
python3 {baseDir}/scripts/scan-network.py --subnet 192.168.1.0/24

# Quick ARP-based scan (faster)
python3 {baseDir}/scripts/scan-network.py --subnet 192.168.1.0/24 --arp

Options

• --subnet CIDR — Network range to scan (required)
• --arp — Use ARP scan (faster, requires root)
• --known FILE — JSON file with known devices (MAC → name mapping)
• --state FILE — State file for tracking changes (default: ~/.network-state.json)
• --alerts — Only output when unknown devices are found
• --json — Output as JSON
• --table — Pretty-print as table

State Tracking

The monitor saves device state between runs:

{
  "last_scan": "2026-03-29T12:00:00",
  "devices": {
    "AA:BB:CC:DD:EE:FF": {
      "ip": "192.168.1.100",
      "hostname": "my-laptop",
      "first_seen": "2026-03-29T10:00:00",
      "last_seen": "2026-03-29T12:00:00",
      "status": "online"
    }
  },
  "unknown_devices": ["11:22:33:44:55:66"]
}

Alert Mode

Run with --alerts for cron/heartbeat integration:

# Only prints output if unknown devices are detected
python3 scan-network.py --subnet 192.168.1.0/24 --alerts

Known Devices Format

Create a known-devices.json:

{
  "AA:BB:CC:DD:EE:FF": "My Laptop",
  "11:22:33:44:55:66": "Smart TV",
  "DE:AD:BE:EF:00:00": "Game Console"
}

Notes

• ARP scan requires root: sudo python3 scan-network.py --arp
• nmap scan works without root but is slower
• Works on Linux and macOS
• No external API dependencies