Scan ports on a machine with nmap

Nmap Commands to Scan Ports, Detect Services, Operating Systems, and Identify Vulnerabilities

TCP and UDP Port Scanning

• TCP Port Scan (SYN scan):

This scan is fast and uses “SYN scan” mode, which is less detectable and helps identify open TCP ports.

• UDP Port Scan:

This scan detects open UDP ports, though it’s generally slower. You can combine it with the TCP scan for comprehensive results.

• Specific Ports Scan (TCP and UDP):

Example: nmap -p 80,443,8080 <target IP address>. This scans only the specified ports (in this case, ports 80, 443, and 8080).

Operating System Detection

• OS Detection:

This option attempts to identify the target’s operating system based on the responses from the TCP/IP stack.

Service and Version Detection

• Service and Version Detection:

This command identifies the open services on each discovered port and attempts to determine their version.

• Full Scan with OS and Version Detection:

This advanced scan combines multiple features: port scanning, OS detection, service detection, and some basic scripts.

Vulnerability Detection

• Using NSE Scripts to Identify Vulnerabilities:

This runs available vulnerability detection scripts in Nmap’s script library, helping identify known vulnerabilities.

Other Common Uses

• Stealth Scans (bypassing some firewalls):

These scans send specific packets designed to avoid detection by some firewalls.

• Fast Scan for Active Hosts and Common Services:

The -F option limits the scan to the most common ports, saving time.