Netgear FVX538v1 – ProSafe VPN Firewall Dual WAN with 8-Port 10/100 and 1 Gigabit LAN Port Switch 参照マニュアル

Firewall Protection and Content Filtering

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If you want to block Instant Messenger usage by employees during working hours, you can create 
an outbound rule to block that application from any internal IP address to any external address 
according to the schedule that you have created in the Schedule menu. 

You can also have the firewall log any attempt to use Instant Messenger during that blocked 
period.

Services are functions performed by server computers at the request of client computers. You can 
configure up to 125 custom services. 

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 FVX538 already holds a list of many service port numbers, you are not limited to 
these choices. Use the Services screen 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, as 
shown in 

Figure 4-16

.