21 # FTP (File Transfer Protocol)
22 # SSH (Secure Shell)
23 # Telnet
25 # SMTP (Simple Mail Transfer Protocol)
53 # DNS (Domain Name System)
80 # HTTP (Hypertext Transfer Protocol)
110 # POP3 (Post Office Protocol version 3)
123 # NTP (Network Time Protocol)
143 # IMAP (Internet Message Access Protocol)
443 # HTTPS (HTTP Secure)
465 # SMTPS (SMTP Secure)
587 # SMTP (Submission)
993 # IMAPS (IMAP Secure)
995 # POP3S (POP3 Secure)
1433 # MS SQL Server
1521 # Oracle Database
1701 # L2TP (Layer 2 Tunneling Protocol)
1723 # PPTP (Point-to-Point Tunneling Protocol)
3306 # MySQL
3389 # Remote Desktop Protocol (RDP)
500 # IPSec VPN (Internet Protocol Security)
5432 # PostgreSQL
5900 # VNC (Virtual Network Computing)
8080 # HTTP Alternate