Cisco ASA 5505 Configuration Manual page 499

Information About NAT
This chapter provides an overview of how Network Address Translation (NAT) works on the adaptive
security appliance. This chapter includes the following sections:
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To start configuring NAT, see
Note
"Configuring Twice NAT."
Why Use NAT?
Each computer and device within an IP network is assigned a unique IP address that identifies the host.
Because of a shortage of public IPv4 addresses, most of these IP addresses are private, not routable
anywhere outside of the private company network. RFC 1918 defines the private IP addresses you can
use internally
Table 26-1
Network Class
Class A addresses
Class B addresses
Class C addresses
OL-20339-01
Why Use NAT?, page 26-1
NAT Terminology, page 26-2
NAT Types, page 26-2
NAT in Routed and Transparent Mode, page 26-12
How NAT is Implemented, page 26-15
NAT Rule Order, page 26-19
Mapped Address Guidelines, page 26-20
DNS and NAT, page 26-21
Where to Go Next, page 26-23
Chapter 27, "Configuring Network Object NAT,"
(Table 26-1):
Private IP Addresses
Address Block
10.0.0.0/8
172.16.0.0/12
192.168.0.0/16
C H A P T E R
Starting Address Ending Address
10.0.0.0 10.255.255.255
172.16.0.0 172.31.255.255
192.168.0.0 192.168.255.255
Cisco ASA 5500 Series Configuration Guide using ASDM
26
or Chapter 28,
Approximate Hosts
16,000,000
1,000,000
65,000
26-1