Netgear DG834GUV5 사용자 설명서

3-10

Protecting Your Network

As you define new rules, they are added to the tables in the Firewall Rules screen, as shown:

For any traffic attempting to pass through the firewall, the packet information is subjected to the 
rules in the order shown in the rules table, beginning at the top and proceeding to the default rules 
at the bottom. In some cases, the order of precedence of two or more rules might be important in 
determining the disposition of a packet. The Move button allows you to relocate a defined rule to a 
new position in the table.

Services are functions performed by server computers at the request of client computers. For 
example, Web servers serve Web pages, time servers serve time and date information, and game 
hosts serve data about other players’ moves. When a computer on the Internet sends a request for 
service to a server computer, the requested service is identified by a service or port number. This 
number appears as the destination port number in the transmitted IP packets. For example, a packet 
that is sent with destination port number 80 is an HTTP (Web server) request.

The service numbers for many common protocols are defined by the Internet Engineering Task 
Force (IETF) and published in RFC 1700, “Assigned Numbers.” Service numbers for other 
applications are typically chosen from the range 1024 to 65535 by the authors of the application.

Although the modem router already holds a list of many service port numbers, you are not limited 
to these choices. Use the following procedure to define your own services.