ZyXEL Communications Prestige 941, Руководство пользователя, Страница: 62 / 99

Prestige 941 Cable Router
6-6 F ilter Configuration
6.3 Filter Types and SUA
There are two types of filter rules, Device Filter (Generic) rules and Protocol Filter (TCP/IP) rules. Device
Filter rules act on the raw data from/to LAN and CABLE. Protocol Filter rules act on the IP and IPX packets.
Generic and TCP/IP filter rules are discussed in more detail in the next section. When NAT/SUA (Network
Address Translation/Single User Account) is enabled, the inside IP address and port number are replaced on a
connection-by-connection basis, which makes it impossible to know the exact address and port on the wire.
Therefore, the Prestige applies the protocol filters to the “native” IP address and port number before
NAT/SUA for outgoing packets and after NAT/SUA for incoming packets. On the other hand, the generic, or
device filters are applied to the raw packets that appear on the wire. They are applied at the point where the
Prestige is receiving and sending the packets; i.e., the interface. The interface can be Ethernet, or any other
hardware port. The following diagram illustrates this.
Figure 6-4 Protocol and Device Filter Sets
6.3.1 TCP/IP Filter Rule
This section shows you how to configure a TCP/IP filter rule. TCP/IP rules allow yo u to base the rule on the
fields in the IP and the upper layer protocol, e.g., UDP and TCP, headers.
To configure a TCP/IP rule, select TCP/IP Filter Rule from the Filter Type field and press [
Enter
] to open
Menu 21.1.1 – TCP/IP Filter Rule , as shown next.