User guide

User Guide 81
CHAPTER 7 Configuring Network
Address Translation
Network address translation (NAT) protects your network by hiding its
internal structure. It also provides an effective way to conserve public IP
addresses when the number of addresses is limited.
At its most basic level, NAT translates the address of a packet from one
value to another. The “type” of NAT performed refers to the method of
translation:
Dynamic NAT
Also called IP masquerading or port address translation. The
Firebox either globally, or on a service-by-service basis, applies its
public IP address to outgoing packets instead of using the IP
address of the session behind the Firebox.
Static NAT
Also called port forwarding. Static NAT works on a port-to-host
basis. Incoming packets from the External network destined for a
specific public address and port are remapped to an address and
port behind the firewall. You must configure each service
separately for static NAT. Typically, static NAT is used for public
services that do not require authentication such as Web sites and
email.