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Port Numbers

Numerical identifiers (0-65535) used to route network traffic to specific services on a device.

NetworkingAlso called: "tcp ports", "udp ports", "network ports"

Ports allow multiple services to operate on a single IP address.

Port ranges

  • 0-1023: Well-known ports (HTTP=80, HTTPS=443, SSH=22).
  • 1024-49151: Registered ports for applications.
  • 49152-65535: Dynamic/private ports for temporary connections.

Common services

  • 22: SSH (Secure Shell).
  • 25: SMTP (Email sending).
  • 53: DNS (Domain resolution).
  • 443: HTTPS (Secure web).
  • 3389: RDP (Remote Desktop).

Security implications

  • Open ports increase attack surface.
  • Scan for unnecessary services and close unused ports.
  • Firewall rules should restrict access by port and IP.