NETGEAR DG834GUV5 user manual Services, Order of Precedence for Rules

DG834GUv5 Wireless Router with Built-in DSL Modem User Manual

Order of Precedence for Rules

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

Figure 3-7

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

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.

3-10 Protecting Your Network

v1.0, May 2009