Nat; Chapter 10 Nat; Overview; What You Can Do In This Chapter - ZyXEL Communications LTE3202-M430 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 LTE3202-M430. 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 LTE3202-M430, which is 192.168.1.1.
Figure 49 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 LTE3202-M430.

10.1.1 What You Can Do in this Chapter

• Use the IP/Port Forwarding screen to view and configure port forwarding rules
73).
• Use the DMZ screen to configure a default server
• Use the ALG screen to enable or disable SIP (VoIP) ALG (Application Layer Gateway) in the LTE3202-
M430 (Section 10.4 on page
• Use the Pass through screen to enable/disable ALGs in the LTE3202-M430
C
LTE
(Section 10.3 on page
74).
LTE3202-M430 User's Guide
72
H A P T E R
(Section 10.2 on page
74).
(Section 10.5 on page
10

NAT

75).