Nat; Chapter 12 Nat; Overview; What You Can Do - ZyXEL Communications EMG3425-Q10A User Manual

Dual-band wireless ac/n gigabit ethernet gateway
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12.1 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 EMG3425-Q10A. 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 EMG3425-Q10A,
which is 192.168.1.1.
Figure 55 NAT Example
A: 192.168.1.33
FTP, Telnet, SNMP
Ports 21 to 25
B: 192.168.1.34
Port 80
C: 192.168.1.35
This chapter discusses how to configure NAT on the EMG3425-Q10A.
Note: You must create a firewall rule in addition to setting up NAT, to allow traffic from
the WAN to be forwarded through the EMG3425-Q10A.

12.1.1 What You Can Do

• Use the General screen to enable NAT
C
HAPTER
LAN
WAN
192.168.1.1
(Section 12.2 on page
EMG3425-Q10A User's Guide
99
IP address
assigned by ISP
101).
1 2

NAT

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