Watchguard Wireless Router User's Guide download pdf (Page 21)

Ports

User Guide 7

Some services are necessary, but each service you add to your secu-

rity policy can also add a security risk. To send and receive data, you

must “open a door” in your computer, which puts your network at

risk. Attackers can use open access of a service to try to get into a

network. We recommend that you only add services that are neces-

sary for your business.

Ports

Usually, a port is a connection point where you use a socket and a

plug to connect two devices. Computers also have ports that are not

physical locations. These ports are “logical connection places” for

programs or applications on a computer in a network. Some applica-

tions, such as HTTP, have ports with assigned numbers. These are

“well-known ports.” Other application processes are assigned port

numbers dynamically for each connection.

Each Internet service that uses TCP uses a unique port number.

When a client starts a connection to a server, it connects to, for

example, port 25 on the remote computer. Port 25 is given to the

SMTP protocol, which is the service that supplies electronic mail.

Most services are given a port number in the range from 0 to 1024,

but possible port numbers range from 0 to 65535.

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Watchguard Wireless Router User's Guide Page 21