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

Prestige 316 Broadband Sharing Gateway / Wireless LAN
7.4

Filter Types and SUA

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.

7.5.1 LAN Traffic

LAN traffic filter sets may be useful to block certain packets, reduce traffic and prevent security breaches.
Go to Menu 3.1 (shown next) and enter the number(s) of the filter set(s) that you want to apply as
appropriate. You can choose up to four filter sets (from twelve) by entering their numbers separated by
commas, e.g., 3, 4, 6, 11. Input filter sets filter incoming traffic to the Prestige and Output filter sets filter
outgoing traffic from the Prestige. The factory default set, NetBIOS_LAN, can be inserted in the Protocol
Filters field under Input Filter Sets in Menu 3.1 to block NetBIOS traffic to the Prestige from the LAN.
7-16
Figure 7-13 Protocol and Device Filter Sets
Filters