P-870H/HW Series User’s Guide
117
C
H A P T E R
8
Network Address Translation
(NAT)
8.1 Overview
This chapter discusses how to configure NAT on the ZyXEL Device.
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.
8.1.1 What You Can Do in this Chapter
• The Port Forwarding screen lets you configure forward incoming service
requests to the server(s) on your local network (
).
• The Address Mapping screen lets you configure the ZyXEL Device's address
mapping settings (
).
• The Trigger Port screen lets you change the ZyXEL Device's trigger port
settings (
• The DMZ Host screen lets you configure a default server (
• The ALG screen lets you enable SIP ALG on the ZyXEL Device (
8.2 What You Need to Know
The following terms and concepts may help as you read through this chapter.
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,
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