ZyXEL Communications SBG3300 series User Manual page 18

NAT provides system administrators with an easy solution to create a private IP
network for security and IP management. Powered by NAT technology, the SBG3300
supports complete NAT mapping and most popular Internet multimedia applications.
This functionality is best demonstrated with the NAT port forwarding feature
implemented in the CPE. In a scenario shown in the above diagram, we have an FTP
server installed behind the CPE with an IP assigned by the local DHCP server
(192.168.1.33). How should we configure the SBG3300, so that the notebook at the
WAN site can access the FTP server? The following step-by-step guide illustrates the
setup procedure.
PS: Make sure that NAT is enabled on the WAN interface.