8
Network Address Translation (NAT)
8.1 Overview
This chapter discusses how to configure NAT on the
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.
8.1.1What 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 (Section 8.3 on page 184).
•The Trigger Port screen lets you change the
•The DMZ Host screen lets you configure a default server (Section 8.5 on page 192).
•The ALG screen lets you enable SIP ALG on the
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.
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