What are the most common vulnerable network ports?

The most targeted vulnerable ports include Port 21 (FTP - cleartext login), Port 23 (Telnet - unencrypted admin access), Port 135 & 445 (Microsoft RPC & SMB - heavily targeted by ransomware such as WannaCry), Port 3389 (RDP - vulnerable to credential stuffing), and Port 80 (HTTP - prone to man-in-the-middle sniffing).

How does Nmap probe open ports?

Nmap scans networks by sending custom packets and analyzing returning socket states. The most common techniques are SYN Stealth scans (nmap -sS) which initiate half-open TCP connections, Service Version detection (nmap -sV) which banner-grabs port headers, and Script scans (nmap -sC) which evaluate vulnerability signatures.

What is the security risk of having open ports?

An open port is a gate linked to a background service. If that service is misconfigured, has default credentials, or contains unpatched buffer overflow CVE vulnerabilities, attackers can exploit it to execute remote command executions (RCE) or move laterally within the network backplane.

Interactive Infosec Utilities

Network Ports & Protocols Reference

Audit your firewall setups and open socket configurations. This interactive directory lists the 110 most critical network ports, providing protocols, official designations, security descriptions, vulnerability insights, and pre-packaged Nmap diagnostic commands.

Total Mapped

131

Plaintext / Legacy

High-Risk / Vulnerable

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Automated NMAP Scan Script Compiler

Target Host / IP Domain

Scan Mode Profile

Target Ports (Comma-separated or range)

Skip Host Discovery (-Pn) Force DNS Lookup (-R)

Active Scan Parameters:

SYN Stealth scan resolves raw socket packet frames. Skip Host Discovery (-Pn) treats all hosts as active, dodging firewall packet drops.

Calculated entirely client-side. Ensure auth before auditing networks.

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Network Ports & Protocols Reference

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Automated NMAP Scan Script Compiler

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