ZyXEL Communications NBG-419N User Manual
NBG-419N v2 User’s Guide
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H A P T E R
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Network Address Translation (NAT)
16.1 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.
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.
Each packet has two addresses – a source address and a destination address. For outgoing packets,
NAT maps private (local) IP addresses to globally unique ones required for communication with
hosts on other networks. It replaces the original IP source address in each packet and then
forwards it to the Internet. The Router keeps track of the original addresses and port numbers so
incoming reply packets can have their original values restored. The following figure illustrates this.
NAT maps private (local) IP addresses to globally unique ones required for communication with
hosts on other networks. It replaces the original IP source address in each packet and then
forwards it to the Internet. The Router keeps track of the original addresses and port numbers so
incoming reply packets can have their original values restored. The following figure illustrates this.
Figure 98
NAT Example
For more information on IP address translation, refer to RFC 1631, The IP Network Address
Translator (NAT).
Translator (NAT).
16.2 What You Can Do
• Use the General screen (
) to enable NAT and set a default server.
• Use the Application screen (
) o forward incoming service requests to
the server(s) on your local network.
• Use the Advanced screen (
) to change your Router’s trigger port
settings.