Using Allow and Deny

• By turning on the firewall it will deny all incoming connections by default
• You then need to allow (enable) the connections depending your needs
• The connection can be open by defining the port, service name or application profile

Common Ports

Here is a brief list of standard ports and their designations:

21 – FTP

22 – SSH

25 – SMTP (sending email)

53 – DNS (domain name service)

80 – HTTP (web server)

110 – POP3 (email inbox)

123 – NTP (Network Time Protocol)

143 – IMAP (email inbox)

443 – HTTPS (secure web server)

465 – SMTPS (send secure email)

631 – CUPS (print server)

993 – IMAPS (secure email inbox)

995 – POP3 (secure email inbox)