ZyXEL FSG1100HN User Guide - Page 63

Chapter 7 NAT 7 NAT 7.1 Overview This chapter discusses how to configure NAT on the FSG1100HN. 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 FSG1100HN 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 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 FSG1100HN. 7.2 What You Can Do • Use the NAT General screen (64) to enable NAT, NAT loopback, SIP ALG, and RTSP ALG. • Use the NAT DMZ screen (66) to change your FSG1100HN's DMZ settings. • Use the NAT Port Forwarding screen (67) change your FSG1100HN's port forwarding settings. FSG1100HN User's Guide 63