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EMG2926-Q10A User’s Guide

CHAPTER 12

NAT

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 192.168.0.35 to a third (C in the example).

You assign the LAN IP addresses to the devices (A to D) connected to your EMG2926-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 uses the IP address of the EMG2926-Q10A,

which is 192.168.0.1.

Figure 67 NAT Example

This chapter discusses how to configure NAT on the EMG2926-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 EMG2926-Q10A.

A: 192.168.0.33

B: 192.168.0.34

C: 192.168.0.35

IP address

192.168.0.1

WANLAN

assigned by ISP

FTP, Telnet, SNMP

Port 80

Ports 21 to 25

1 2 ... 94 95 96 97 98 99 100 101 102 103 104 ... 164 165

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