ZyXEL Communications NBG-417N Network Address Translation (NAT), 11.1 Overview, 11.2What You Can Do

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Network Address Translation (NAT)

11.1 Overview

This chapter discusses how to configure NAT on the NBG-417N.

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.

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 NBG-417N 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 69 NAT Example

For more information on IP address translation, refer to RFC 1631, The IP Network Address Translator (NAT).

Note: You must create a firewall rule in addition to setting up NAT, to allow traffic from the WAN to be forwarded through the NBG-417N.

11.2What You Can Do

•Use the General screen (Section 11.3 on page 114) to enable NAT and set a default server.

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NBG-417N User’s Guide