Manage network services and ports

A network port is an endpoint of communication in an operating system. While the term is also used for hardware devices, in software it is a logical construct that identifies a specific process or a type of service. In other words, a network port is conceptually different from hardware ports like USB, memory card, and even the wired network connection.

Computers and devices can access many different network services at the same time by communicating on different network ports. Each network service or communication protocol has an associated port number. Some port numbers are specified by international standards, and therefore they are universally recognized. Other port numbers are claimed by proprietary software, and in most cases they can be changed in the software settings if there is a conflict with other software or services.

Firewalls control network traffic by either accepting or refusing communication on these network ports. If a port is open, it accepts communication, and if a port is closed, it refuses communication. Almost every layer of a network -- from the operating system on an individual computer or device, to the router that manages traffic within a network, to the gateway that manages traffic between networks -- has its own firewall.

The documentation for your ICS software should include a list of network ports that are commonly used by the software. Given the nature of ICS, the list typically includes services like web, email, file transfer, external databases, device drivers, and the ICS software itself for server-client communications. Configure the firewalls to open only those network ports that are actually used by your ICS. Disable all unused services and close all unused ports.