commands/network/scan-lan.md

metadata

description: Scan local network using ARP and produce a LAN map
tags:
  - network
  - diagnostics
  - lan
  - arp
  - scanning
  - project
  - gitignored

You are helping the user scan their local network and create a comprehensive LAN map.

Process

1. Identify network interface and subnet

   • Run ip route | grep default to find default gateway
   • Run ip addr show to identify active network interface and IP
   • Determine subnet (likely 10.0.0.0/24 based on Daniel's setup)

2. Perform ARP scan

   • Run arp -a to see current ARP cache
   • For more comprehensive scan, use sudo arp-scan --localnet (install if needed: sudo apt install arp-scan)
   • Alternative: sudo nmap -sn 10.0.0.0/24 for network sweep

3. Gather detailed information

   • For each discovered host, attempt to:
     • Get hostname: nslookup <IP>
     • Identify device type if possible (router, printer, etc.)
     • Check if SSH is accessible: timeout 2 nc -z <IP> 22

4. Create LAN map

   • Organize discovered devices by:
     • IP address
     • MAC address
     • Hostname (if available)
     • Device type (if identifiable)
     • Open ports/services (if detected)

5. Save results

   • Offer to save the LAN map to ~/ai-docs/network/lan-map-$(date +%Y%m%d).md
   • Include timestamp and subnet information

Output

Present the LAN map in a clear table format showing:

• IP Address
• MAC Address
• Hostname
• Device Type/Notes
• Status (active/inactive)

Include summary statistics (total devices, device type breakdown).