Important service ports no:

Port No.     20         FTP-Data   ( FTP Data )
Port No.     21         FTP           ( FTP connection)
Port No.     22         SSH
Port No.     25         SMTP
Port No.     53         DNS
Port No.     80         HTTP
Port No.    110        POP3
Port No.    143        IMAP
Port No.    443        HTTPS
Port No.   3306       MySQL
Port No.   8443       Plesk Panel (with SSL)
Port No.   8880       Plesk Panel
Port No.   2082      cPanel
Port No    2083      cPanel (with SSL)
Port No.   2086      WHM
Port No.   2087      WHM (with SSL)
Port No.   2095      Webmail
Port No.   2096      Webmail (with SSL)
Port No.   1433       MSSQL
Port No.   3389.      RDP
Port No.   23           Telnet
Port No.   80           IIS