Network Address Translation (Nat) Screens; Nat Overview; Nat Virtual Servers; Virtual Server: Services And Port Numbers - ZyXEL Communications P-663H-51 User Manual

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H A P T E R
Network Address Translation
This chapter discusses how to configure NAT on the ZyXEL Device.

7.1 NAT Overview

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 to a different IP address known within another network.

7.2 NAT Virtual Servers

Configure NAT virtual server (port forwarding) entries to have the ZyXEL Device forward
traffic from the WAN to LAN computers.
You might do this to get particular games or services to work through NAT. You can also
make servers, for example, web or FTP, visible to the outside world even though NAT makes
your whole inside network appear as a single computer to the outside world.
You may enter a single port number or a range of port numbers to be forwarded, and the local
IP address of the desired server. The port number identifies a service; for example, web
service is on port 80 and FTP on port 21. In some cases, such as for unknown services or
where one server can support more than one service (for example both FTP and web service),
it might be better to specify a range of port numbers. You can allocate a server IP address that
corresponds to a port or a range of ports.
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 your ISP.

7.2.1 Virtual Server: Services and Port Numbers

See Appendix D on page 185
P-663H-51 User's Guide
(NAT) Screens
for commonly used port numbers.
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