Free network scanner and port inventory guide

Good For

• port inventory
• migration discovery
• small network audits
• exposed service review
• asset cleanup

How to Use It

1. Start with the smallest useful scope: one host, one subnet, or a known server list.
2. Use built-in Windows commands for single-host checks before reaching for a subnet scanner.
3. Use Nmap or another approved scanner when you need service/version discovery across a defined range.
4. Avoid aggressive timing, intrusive scripts, or internet-facing scans unless the network owner approved them.
5. Compare findings against CMDB, firewall policy, server owners, and expected service inventory.
6. Export results and mark each finding as expected, unknown, stale, or cleanup candidate.

Execution Modes

• local
• remote-host-list
• ad-filtered

Inputs and Outputs

Inputs

• target host
• CSV or TXT host list
• Active Directory computer scope
• approved subnet range

Outputs

• verbose-console
• csv
• operator-notes

Command Starter

Safe to run: read-only

Test-NetConnection server01.contoso.com -Port 443
Get-NetTCPConnection | Select-Object LocalAddress, LocalPort, RemoteAddress, RemotePort, State, OwningProcess
nmap -sV -Pn 192.168.1.0/24

Validation

• Scan scope, source host, timing, and permission are documented.
• Open ports are mapped to owners or an unknown-service queue.
• Unexpected services are verified from a second source before remediation.

Reporting

• export host and port inventory to CSV
• group unknown services by subnet, owner, and risk
• promote repeated use into an exposed-service inventory report

Safety Notes

• Scanning can trigger alerts or affect fragile devices; get scope approval first.
• Do not run intrusive Nmap scripts against production systems without explicit authorization.
• Do not treat scan output as ownership truth until confirmed.