3-19
Cisco ASA Series Firewall CLI Configuration Guide
Chapter3 Information About NAT
NAT Interfaces
For section 2 rules, for example, you have the following IP addresses defined within network objects:
192.168.1.0/24 (static)
192.168.1.0/24 (dynamic)
10.1.1.0/24 (static)
192.168.1.1/32 (static)
172.16.1.0/24 (dynamic) (object def)
172.16.1.0/24 (dynamic) (object abc)
The resultant ordering would be:
192.168.1.1/32 (static)
10.1.1.0/24 (static)
192.168.1.0/24 (static)
172.16.1.0/24 (dynamic) (object abc)
172.16.1.0/24 (dynamic) (object def)
192.168.1.0/24 (dynamic)
NAT Interfaces
You can configure a NAT rule to apply to any interface (in other words, all interfaces), or you can identify
specific real and mapped interfaces. You can also specify any interface for the real address, and a specific
interface for the mapped address, or vice versa.
For example, you might want to specify any interface for the real address and specify the outside
interface for the mapped address if you use the same private addresses on multiple interfaces, and you
want to translate them all to the same global pool when accessing the outside.
Note For transparent mode, you must choose specific source and destination interfaces.
Routing NAT Packets
The ASA needs to be the destination for any packets sent to the mapped address. The ASA also needs to
determine the egress interface for any packets it receives destined for mapped addresses. This section
describes how the ASA handles accepting and delivering packets with NAT, and includes the following
topics:
•Mapped Addresses and Routing, page3-20
•Transparent Mode Routing Requirements for Remote Networks, page3-21
•Determining the Egress Interface, page3-22