Nat; Chapter 8 Nat; Overview; What You Can Do - ZyXEL Communications NR2101 User Manual

8.1 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 NR2101. 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 NR2101, which is 192.168.1.1.
Figure 64 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 NR2101.

8.1.1 What You Can Do

• Use the NAT Settings screen to configure your NR2101's VPN pass-through and port forwarding settings
(Section 8.2 on page 76).
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NAT