Filter Types And Nat; Figure 7-14 Example Filter Rules Summary - ZyXEL Communications Prestige 310 User Manual

Prestige 310 Broadband Sharing Gateway
After you've created the filter set, you must apply it.
Step 1. Enter 11 from the main menu to display menu 11.
Step 2. Go to the Edit Filter Sets field, press the [SPACE BAR] to select No and press [ENTER].
Step 3. This brings you to menu 11.5. Apply the TELNET_FTP_WAN filter set (filter set 7) as shown in
Figure 7-17.
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 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
Prestige 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 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 figure illustrates this.
7-16
Menu 21.1 - Filter Rules Summary
# A Type
- - ---- ------------------------------------------------------------
1 Y IP Pr=6, SA=0.0.0.0, DA=0.0.0.0, DP=21
2 Y IP Pr=6, SA=0.0.0.0, DA=0.0.0.0, DP=23
3 N
4 N
5 N
6 N
Enter Filter Rule Number (1-6) to Configure:

Figure 7-14 Example Filter Rules Summary

Filter Rules M m n
N D N
N D F
Filter Configuration