You can configure the router as a virtual server
so that remote users accessing services such as the Web or FTP at your
local site via public IP addresses can be automatically redirected to
local servers configured with private IP addresses. In other words,
depending on the requested service (TCP/UDP port number), this modem
redirects the external service request to the appropriate server (located
at another internal IP address). This tool can support both port ranges,
multiple ports, and combinations of the two.