Nmap - Network Scanner

Nmap is the industry-standard tool for network discovery and security auditing, used to identify live hosts, open ports, and running services.

What Nmap Does

Nmap sends specially crafted packets to target hosts and analyzes the responses to determine which hosts are online, which ports are open, and what services and versions are running on them.

Common Scan Types

A TCP SYN scan (-sS) is fast and stealthy, a TCP connect scan (-sT) completes the full handshake, and a UDP scan (-sU) checks for open UDP services, each suited to different testing scenarios.

Useful Command Options

Flags like -A enable OS and version detection with script scanning, -p specifies which ports to scan, and -T controls scan timing to balance speed against the risk of detection.

Role in the Pentesting Workflow

Nmap is typically one of the first tools used during the scanning phase, providing the map of live systems and services that guides which vulnerabilities to investigate further.