NETGEAR MR314 Reference Manual page 66

Although the router causes your entire local network to appear as a single machine to the Internet,
you can make local servers for different services (for example, FTP or HTTP) visible and available
to the Internet. This is done using the PORTS menu. From the Main Menu of the browser
interface, under Advanced, click on PORTS to view the port forwarding screen, shown in
Figure 5-4
Requested services are identified by port numbers in an incoming IP packet. For example, a packet
that is sent to the external IP address of your router and destined for port number 80 is an HTTP
(Web server) request, and port 21 is an FTP request. Examples of port numbers are shown at the
top of the PORTS menu, although you are not limited to these choices. See IETF RFC1700,
"Assigned Numbers," for port numbers for common protocols..
Many residential broadband ISP accounts do not allow you to run any server
processes (such as a Web or FTP server) from your location. Your ISP may periodically
check for servers and may suspend your account if it discovers any active services at
your location. If you are unsure, refer to the Acceptable Use Policy of your ISP.