Port scanning is a fundamental technique in cybersecurity used to identify open ports and services running on a target system. It helps security professionals understand the attack surface before performing further assessments.

What Is Port Scanning?

Port scanning involves sending packets to various ports on a host and analyzing the responses. The goal is to determine which ports are open, closed, or filtered.

Common tools include:

• Nmap

• Masscan

• Unicornscan

Why It Matters

Open ports can expose services that may have known vulnerabilities. Identifying them early allows defenders to:

• Detect misconfigurations

• Close unused ports

• Patch outdated services

Types of Port Scans

• TCP Connect Scan – Completes the full TCP handshake

• SYN Scan – Half-open scan, stealthier and faster

• UDP Scan – Checks for non-TCP services

• FIN/Xmas/NULL Scans – Used to bypass firewalls or IDS

Final Note

While port scanning is essential for security testing, unauthorized scans can be seen as hostile activity. Always ensure you have permission before scanning any system.