Network address translation (nat) screens, 1 overview, 1 what you can do in the nat screen – ZyXEL Communications P-2900-4HB User Manual
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P-2900-4HB User’s Guide
59
C
H A P T E R
6
Network Address Translation
(NAT) Screens
6.1 Overview
This chapter discusses how to configure NAT on the ZyXEL Device. 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.
6.1.1 What You Can Do in the NAT Screen
Use the NAT Mode screen (
) to disable NAT, or enable and
configure NAT mapping rules.
6.1.2 What You Need to Know About NAT
Inside/Outside
Inside/outside denotes where a host is located relative to the ZyXEL Device, for
example, the computers of your subscribers are the inside hosts, while the web
servers on the Internet are the outside hosts.
Global/Local
Global/local denotes the IP address of a host in a packet as the packet traverses a
router, for example, the local address refers to the IP address of a host when the
packet is in the local network, while the global address refers to the IP address of
the host when the same packet is traveling in the WAN side.
NAT
In the simplest form, NAT changes the source IP address in a packet received from
a subscriber (the inside local address) to another (the inside global address)
before forwarding the packet to the WAN side. When the response comes back,