Firewalls and Ports
A firewall is a system that protects a local network from attack by unauthorized users attempting to access the LAN from the Internet. The word firewall has entered the lexicon of Internet jargon, and it is one of many computer terms that can fall within a wide range of definitions. Firewalls perform a number of functions. However, one of the most basic features of a firewall is something that is pertinent to this hour.
That important feature is the capability of a firewall to block off access to specific TCP and UDP ports. The word firewall, in fact, is sometimes used as a verb, meaning to close off access to a port.
For example, to initiate a secure shell (SSH) session with the server, a client machine must send a request ...
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