ZyXEL P-791R v2 User Guide - Page 224

Filter Types and NAT, 25.5 Applying a Filter

Page 224 highlights

Chapter 25 Filter Configuration 4 This brings you to menu 11.1.4. Apply a filter set (our example filter set 3) as shown in Figure 108 on page 191. 5 Press [ENTER] to confirm after you enter the set numbers and to leave menu 11.1.4. 25.4 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 NAT (Network Address Translation) 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 ZyXEL Device applies the protocol filters to the "native" IP address and port number before NAT for outgoing packets and after 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 ZyXEL Device is receiving and sending the packets; in other words the interface. The interface can be an Ethernet port or any other hardware port. The following diagram illustrates this. Figure 145 Protocol and Device Filter Sets 25.5 Applying a Filter This section shows you where to apply the filter(s) after you design it (them). The ZyXEL Device already has filters to prevent NetBIOS traffic from triggering calls, and block incoming telnet, FTP and HTTP connections. 25.5.1 Applying LAN Filters 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, for example 3, 4, 6, 11. Input filter sets filter incoming traffic to the ZyXEL Device and output filter sets filter outgoing traffic from the ZyXEL Device. 224 P-791R v2 User's Guide

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Chapter 25 Filter Configuration
P-791R v2 User’s Guide
224
4
This brings you to menu 11.1.4. Apply a filter set (our example filter set 3) as shown in
Figure 108 on page 191
.
5
Press
[ENTER
] to confirm after you enter the set numbers and to leave menu 11.1.4.
25.4
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 NAT (Network Address Translation) 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 ZyXEL Device applies the protocol
filters to the “native” IP address and port number before NAT for outgoing packets and after
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 ZyXEL Device is
receiving and sending the packets; in other words the interface. The interface can be an
Ethernet port or any other hardware port. The following diagram illustrates this.
Figure 145
Protocol and Device Filter Sets
25.5
Applying a Filter
This section shows you where to apply the filter(s) after you design it (them). The ZyXEL
Device already has filters to prevent NetBIOS traffic from triggering calls, and block
incoming telnet, FTP and HTTP connections.
25.5.1
Applying LAN Filters
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, for example 3, 4, 6, 11. Input filter sets filter
incoming traffic to the ZyXEL Device and output filter sets filter outgoing traffic from the
ZyXEL Device.