Certain ports must be open for routine Internet communication, but an open port can also be a potential entrance for an attacker. It is recommended you open only the ports you need.
The control of ports is part of Zone security, so is specific to a given Zone.
The Defined Ports tab in Zone security controls which standard ports are open to incoming and outgoing traffic. Any port not defined on the Defined Ports is closed. To define additional ports, use Custom level security and then create your own port rules on the Custom Ports tab.
Click a link below to view the port settings for each Zone security level:
You can define additional ports in Custom level - Custom Ports.
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