Network Address Translation (Nat); Overview; What You Can Do In This Chapter; What You Need To Know - ZyXEL Communications P-870HN-51B - V1.0 Manual

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H A P T E R
Network Address Translation

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 Trigger Port screen lets you change the ZyXEL Device's trigger port
settings (Section 8.4 on page
• The DMZ Host screen lets you configure a default server
142).
• The ALG screen lets you enable SIP ALG on the ZyXEL Device
page 142).

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,
NAT translates the destination address (the inside global address) back to the
inside local address before forwarding it to the original inside host.
P-870HN-51b User's Guide
(Section 8.3 on page
137).
8
(NAT)
134).
(Section 8.5 on page
(Section 8.6 on
133