WNR2000 Manual: Blocking Access to Internet Services

The WNR2000 router allows you to block the use of certain Internet services by computers on your network. This is called service blocking or port filtering. 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 your network sends a request for service to a server computer on the Internet, 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.

Select Block Services under Content Filtering in the main menu. The Block Services screen displays.

Figure 3-2

Enable service blocking by selecting either Per Schedule or Always, and then click Apply.

To block by schedule, be sure to specify a time period in the Schedule screen. For information about scheduling, see Scheduling Blocking.

Specify a service for blocking by clicking Add. The Block Services Setup screen displays.

Figure 3-3

From the Service Type list, select the application or service to be allowed or blocked. The list already displays several common services, but you are not limited to these choices. To add any additional services or applications that do not already appear, select User Defined. To define a service, first you must determine which port number or range of numbers is used by the application. The service port numbers for many common protocols are defined by the Internet Engineering Task Force (IETF) and published in RFC1700, "Assigned Numbers." Service numbers for other applications are typically chosen from the range 1024 to 65535 by the authors of the application. You can often determine port number information by contacting the publisher of the application, by asking user groups or newsgroups, or by searching.

Enter the starting port and ending port numbers. If the application uses a single port number, enter that number in both fields.

If you know that the application uses either TCP or UDP, select the appropriate protocol. If you are not sure, select Both.

Select the radio button for the IP address configuration you want to block, and then enter the IP addresses in the appropriate fields.

Click Add to enable your Block Services Setup selections.