Common Ports

  • TCP port 21 — FTP (File Transfer Protocol)
  • TCP port 22 — SSH (Secure Shell)
  • TCP port 23 — Telnet
  • TCP port 25 — SMTP (Simple Mail Transfer Protocol)
  • TCP and UDP port 53 — DNS (Domain Name System)
  • TCP port 443 — HTTP (Hypertext Transport Protocol) and HTTPS (HTTP over SSL)
  • TCP port 110 — POP3 (Post Office Protocol version 3)
  • TCP and UDP port 135 — Windows RPC
  • TCP and UDP ports 137–139 — Windows NetBIOS over TCP/IP
  • TCP port 1433 and UDP port 1434 — Microsoft SQL Server