SMC Networks SMC2804WBR V.2 - Manual (Page 63)

Advanced Setup
61
NAT - Network Address Translation
From this section you can configure the Address Mapping, Virtual
Server, and Special Application features that provide control over
the TCP/UDP port openings in the router’s firewall. This section
can be used to support several Internet based applications such
as web, E-mail, FTP, and Telnet.
Address Mapping
Allows one or more public IP addresses to be shared by multiple
internal users. Enter the Public IP address you wish to share into
the Global IP field. Enter a range of internal IPs that will share the
global IP.