D-Link DI-304 Инструкция по эксплуатации онлайн [67/105] 41902

DI-304/DI-304M ISDN Remote Router

from accessing the Internet. Additionally, it can filter out specific packets to trigger

the router to place an outgoing connection.

An Overview of the Firewall

The IP Filter/Firewall includes two types of filter: Call Filter and Data Filter. The

former is designed to block or allow IP packets that will trigger the router to

establish an outgoing connection. The latter is designed to block or allow which

kind of IP packets are allowed to pass through the router when the WAN connection

has been established. It works like this: when an outgoing packet is routed to the

WAN, the IP Filter will decide if the packet should be forwarded to the Call Filter or

Data Filter. If the WAN connection has not been established, the packet will enter

the Call Filter. If the packet is not allowed to trigger router dialing, it will be

dropped. Otherwise, it will initiate a call to establish the WAN connection.

If the WAN connection of the router has been established, the packet will pass

through the Data Filter. Packets match the block rule will be dropped and the

contrary will be sent to the WAN interface. Alternatively, if an incoming packet

enters from the WAN interface, it will pass through the Data Filter directly. If the

packets match the block rule, it will be dropped. Otherwise, it will be sent to the

internal LAN. The filter architecture is shown as below.

The Following sections will explain more about IP Filter/Firewall Setup using Web

Configurator. The Filter has 12 filter sets with 7 filter rules for each set. There are a

total of 84 filter rules for the IP Filter/Firewall Setup. By default, the Call Filter

rules are defined in filter set 1 and the Data Filter rules are defined in filter set 2.