Services - NETGEAR FWG114P Reference Manual

Reference Manual for the ProSafe Wireless 802.11g Firewall/Print Server Model FWG114P

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 FWG114P already holds a list of many service port numbers, you are not limited to
these choices. Use the Services menu to add additional services and applications to the list for use
in defining firewall rules. The Services menu shows a list of services that you have defined.
To define a new service, first you must determine which port number or range of numbers is used
by the application. This information can usually be determined by contacting the publisher of the
application or from user groups of newsgroups. When you have the port number information, go
the Services menu and click on the Add Custom Service button. The Add Services menu will
appear.
To add a service,
Enter a descriptive name for the service so that you will remember what it is.
1.
Select whether the service uses TCP or UDP as its transport protocol.
2.
If you can't determine which is used, select both.
Enter the lowest port number used by the service.
3.
Enter the highest port number used by the service.
4.
If the service only uses a single port number, enter the same number in both fields.
Click Apply.
5.
The new service will now appear in the Services menu, and in the Service name selection box in
the Rules menu.
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December 2003, M-10177-01
Firewall Protection and Content Filtering