Harshvardhan

As a System administrator we have lotof choices to protect our system when we select firewall. All firewall products have a little different functionality and setup, but they have common option to open or close particular ports to protect your web server.

When we installed cPanel and WHM then we are able to use a number of different Services on our system. number of servervices require outside connecton to function properly. So we need specific ports in firewall to be opened for these services to function properly. Here we are giving you list to make your system secure when you are using firewall. So Carefully review this list and make ajustment according to your server requirements.

Firewall Ports
20 FTP (Consider SFTP over SSH as is more secure than FTP)
21 FTP (Consider SFTP over SSH as is more secure than FTP)
22 SSH (Consider switching SSH to a different, non-standard port for security reasons)    
25 SMTP (some ISPs block port 25 so that a mail client cannot reach the mail server to send mail)  
26 SMTP (alternate SMTP port option – see notes for port 25)
37 rdate (needed to retrieve date and time information)
43 whois (part of generic DNS features)
53 bind (DNS)
80 http (Apache / Web)  
110 POP3 (Email)
113 ident (authentication)  
143 IMAP (Email)   
443 https (Web / HTTP over SSL)
465 SMTP (TLS/SSL)
873 rsync (remote sync)  
993 (IMAP SSL)
995 (POP3 SSL)    
2083 cPanel (SSL encrypted)
2087 WHM (SSL encrypted)
2089 Licensing (Must be open to contact license server)
2096 Webmail (Horde, Squirrelmail)
3306 MySQL (MySQL remote connections)

I think this list helpful for you  to secure user of your web server. Make sure test it carefully otherwise server functionality might be at stake.

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