Nat; Chapter 19 Nat; Nat Overview; What You Can Do In This Chapter - ZyXEL Communications ZyWALL USG 200 Series User Manual

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19.1 NAT 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. Use Network Address Translation (NAT) to make computers on a
private network behind the ZyWALL available outside the private network. If the
ZyWALL has only one public IP address, you can make the computers in the
private network available by using ports to forward packets to the appropriate
private IP address.
Suppose 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 and the ISP assigns the WAN IP address. The NAT network appears as a
single host on the Internet.
Figure 315 Multiple Servers Behind NAT Example

19.1.1 What You Can Do in this Chapter

Use the NAT screens (see
of NAT rules and see their configuration details. You can also create new NAT rules
and edit or delete existing ones.
ZyWALL USG 100/200 Series User's Guide
Section 19.2 on page 418) to view and manage the list
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NAT

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