Network Scanner

Network Scanner

Discover and identify devices on local or remote networks using nmap. Gathers IP addresses, hostnames (via reverse DNS), MAC addresses, and vendor identification.

Requirements

• nmap - Network scanning (apt install nmap or brew install nmap)
• dig - DNS lookups (usually pre-installed)
• sudo access recommended for MAC address discovery

Quick Start

# Auto-detect and scan current network
python3 scripts/scan.py

# Scan a specific CIDR
python3 scripts/scan.py 192.168.1.0/24

# Scan with custom DNS server for reverse lookups
python3 scripts/scan.py 192.168.1.0/24 --dns 192.168.1.1

# Output as JSON
python3 scripts/scan.py --json

Configuration

Configure named networks in ~/.config/network-scanner/networks.json:

{
  "networks": {
    "home": {
      "cidr": "192.168.1.0/24",
      "dns": "192.168.1.1",
      "description": "Home Network"
    },
    "office": {
      "cidr": "10.0.0.0/24",
      "dns": "10.0.0.1",
      "description": "Office Network"
    }
  }
}

Then scan by name:

python3 scripts/scan.py home
python3 scripts/scan.py office --json

Commands

# Create example config
python3 scripts/scan.py --init-config

# List configured networks
python3 scripts/scan.py --list

# Scan without sudo (may miss MAC addresses)
python3 scripts/scan.py home --no-sudo

Output Formats

Markdown (default):

### Home Network
*Last scan: 2026-01-28 00:10*

| IP | Name | MAC | Vendor |
|----|------|-----|--------|
| 192.168.1.1 | router.local | AA:BB:CC:DD:EE:FF | Ubiquiti |
| 192.168.1.100 | nas.local | 11:22:33:44:55:66 | Synology |

*2 devices found*

JSON (--json):

{
  "network": "Home Network",
  "cidr": "192.168.1.0/24",
  "devices": [
    {
      "ip": "192.168.1.1",
      "hostname": "router.local",
      "mac": "AA:BB:CC:DD:EE:FF",
      "vendor": "Ubiquiti"
    }
  ],
  "scanned_at": "2026-01-28T00:10:00",
  "device_count": 2
}

Use Cases

• Device inventory: Keep track of all devices on your network
• Security audits: Identify unknown devices
• Documentation: Generate network maps for documentation
• Automation: Integrate with home automation to detect device presence

Tips

• Use sudo for accurate MAC address detection (nmap needs privileges for ARP)
• Configure your local DNS server for better hostname resolution
• Add to cron or heartbeat for daily inventory updates
• Extend MAC_VENDORS in the script for better device identification