Filter Types And Nat; Applying A Filter And Factory Defaults; Figure 7-13 Protocol And Device Filter Sets - ZyXEL Communications Prestige 316 User Manual

7.4

Filter Types and NAT

There are two classes of filter rules, Generic Filter (Device) rules and Protocol Filter (TCP/IP) rules.
Generic Filter rules act on the raw data from/to LAN and WAN. Protocol Filter rules act on the IP packets.
Generic and TCP/IP filter rules are discussed in more detail in the next section. When SUA/NAT (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 SUA/NAT for
outgoing packets and after SUA/NAT 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 when the Prestige is
receiving and sending the packets; i.e., the interface. The interface can be an Ethernet port or any other
hardware port. The following diagram illustrates this.
7.5

Applying a Filter and Factory Defaults

This section shows you where to apply the filter(s) after you design it (them). Sets of factory default filter
rules have been configured in Menu 21 to prevent NetBIOS traffic from triggering calls and block incoming
telnet, FTP and HTTP connections.
Filter Configuration
Prestige 316 Broadband Sharing Gateway/Wireless LAN

Figure 7-13 Protocol and Device Filter Sets

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