Here is a list of most used TCP ports which could be helpful is various cases:

Port 21 –> TCP –> FTP (File Transfer Protocol)
Port 22 –> TCP/UDP –> SSH (ssh,scp copy or sftp)
Port 23 –> TCP/UDP –> Telnet
Port 25 –> TCP/UDP –> SMTP (for sending outgoing emails)
Port 43 –> TCP –> WHOIS function
Port 53 –> TCP/UDP –> DNS Server (DNS lookup uses UDP and Zone transfers use TCP)
Port 70 –> TCP –> Gopher Protocol
Port 79 –> TCP –> Finger protocol
Port 110 –> TCP –> POP3 (for receiving email)
Port 119 –> TCP –> NNTP (Network News Transfer Protocol)
Port 143 –> TCP/UDP –> IMAP4 Protocol (for email service)
Port 194 –> TCP –> IRC
Port 389 –> TCP/UDP –> LDAP (light weight directory access)
Port 443 –> TCP –> Secure HTTP over SSL (https)
Port 465 –> TCP –> Secure SMTP (email) using SSL
Port 990 –> TCP/UDP –> Secure FTP using SSL
Port 993 –> TCP –> Secure IMAP protocol over SSL (for emails)
Port 1433 –> TCP/UDP –> Microsoft SQL server port
Port 2082 –> TCP –> CPanel default port
Port 2083 –> TCP –> CPanel over SSL
Port 2086 –> TCP –> CPanel Webhost Manager (default)
Port 2087 –> TCP –> CPanel Webhost Manager (with https)
Port 2095 –> TCP –> CPanel Webmail
Port 2096 –> TCP –> Cpanel secure webmail over SSL
Port 2222 –> TCP –> DirectAdmin Server Control Panel
Port 3306 –> TCP/UDP –> MySQL Database Server
Port 4643 –> TCP –> Virtuosso Power Panel
Port 5432 –> TCP –> PostgreSQL Database Server
Port 8080 –> TCP –> HTTP port (alternative one for port 80)
Port 8087 –> TCP –> Plesk Control Panel Port (default)
Port 8443 –> TCP –> Plesk Server Control Panel over SSL
Port 9999 –> TCP –> Urchin Web Analytics
Port 10000 –> TCP –> Webmin Server Control Panel