Chapter 10 Nat; Overview; What You Can Do - ZyXEL Communications WAH7601 User Manual

10.1 Overview

NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address of a host in a
packet. For example, the source address of an outgoing packet, used within one network is changed to
a different IP address known within another network.
The figure below is a simple illustration of a NAT network. You want to assign ports 21-25 to one FTP, Telnet
and SMTP server (A in the example), port 80 to another (B in the example) and assign a default server IP
address of 192.168.1.35 to a third (C in the example).
You assign the LAN IP addresses to the devices (A to D) connected to your WAH7601. The ISP assigns the
WAN IP address. The NAT network appears as a single host on the Internet. All traffic coming from A to D
going out to the Internet use the IP address of the WAH7601, which is 192.168.1.1.
Figure 42 NAT Example
Note: You must create a firewall rule in addition to setting up NAT, to allow traffic from the
WAN to be forwarded through the WAH7601.

10.1.1 What You Can Do

• Use the Configure screen to enable NAT
• Use the Entries screen to set a default server and change your WAH7601's port forwarding settings to
forward incoming service requests to the server(s) on your local network
• Use the DMZ screen to configure a default server
C
(Section 10.2 on page
(Section 10.4 on page
WAH7601 User's Guide
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H A P T E R
64).
(Section 10.3 on page
66).
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NAT
65).