Wireless-N ADSL2+ Modem Router DGN2000 Reference Manual
3-12 Protecting Your Network
v1.0, July 2008
The Firewall Rules screen also lets you easily open or close AOL or MSN Instant Messenger
ports:
1. Under Instant Messaging (IM) Ports, select a radio button:
• Close IM Ports. Specifies to disable instant messaging traffic.
• Open IM Ports. Specifies to enable instant messaging traffic. IM ports are open by
default.
2. Click Apply to save your changes.
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 RFC1700, “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 create your own service definitions.
How to Define Services
1. Log in to the modem router at its default LAN address of http://192.168.0.1 with its default
user name of admin, and default password of password, or using whatever password and
LAN address you have chosen for the modem router.
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