ZyXEL nbg-4615 Guida Utente
NBG4615 User’s Guide
177
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H A P T E R
1 9
NAT
19.1 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.
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).
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
NBG4615. 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 NBG4615, which is 192.168.1.1.
NBG4615. 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 NBG4615, which is 192.168.1.1.
Figure 101 NAT Example
This chapter discusses how to configure NAT on the NBG4615.
A: 192.168.1.33
B: 192.168.1.34
C: 192.168.1.35
IP address
192.168.1.1
WAN
LAN
assigned by ISP
FTP, Telnet, SNMP
Port 80
Ports 21 to 25