Dynamic NAT configuration on ASA 55XX

Configure using 8.0 ASA

ciscoasa(config)# nat (inside) 1 192.168.2.0 255.255.255.0
ciscoasa(config)# global (outside) 1 10.2.2.1-10.2.2.10 netmask 255.255.255.0

additional note: Running PAT

ciscoasa(config)# nat (inside) 1 0.0.0.0 0.0.0.0
ciscoasa(config)# global (outside) 1 interface

Configure using 8.3 ASA

ciscoasa(config)# object network MyOutsideRangePool

ciscoasa(config-network-object)# range 10.2.2.1 10.2.2.10

ciscoasa(config)# object network MyInsideNetwork

ciscoasa(config-network-object)# subnet 192.168.2.0 255.255.255.0

ciscoasa(config-network-object)# nat (inside,outside) dynamic MyOutsideRangePool  

Additional example of Dynamic NAT of 2 internal networks
Configure using 8.0 ASA
ciscoasa(config)# nat (inside) 1 192.168.2.0 255.255.255.0
ciscoasa(config)# nat (inside) 2 192.168.3.0 255.255.255.0
ciscoasa(config)# global (outside) 1 10.2.2.1-10.2.2.10 netmask 255.255.255.0
ciscoasa(config)# global (outside) 2 10.2.2.11-10.2.2.20 netmask 255.255.255.0

Configure using 8.3 ASA

ciscoasa(config)# object network MyOutsideRangePool_1

ciscoasa(config-network-object)# range 10.2.2.1 10.2.2.10

ciscoasa(config)# object network MyInsideNetwork_1

ciscoasa(config-network-object)# subnet 192.168.2.0 255.255.255.0

ciscoasa(config-network-object)# nat (inside,outside) dynamic MyOutsideRangePool_1 

ciscoasa(config)# object network MyInsideNetwork_2

ciscoasa(config-network-object)# subnet 192.168.3.0 255.255.255.0

ciscoasa(config-network-object)# nat (inside,outside) dynamic MyOutsideRangePool_2 

ciscoasa(config)# object network MyOutsideRangePool_2

ciscoasa(config-network-object)# range 10.2.2.11 10.2.2.20

Router Configuration: IP NAT

Command:
     ip nat inside source

Mode:
     Router(config) #

Syntax:
     ip nat inside source {list {access-list-number | name} {pool name | interface dialer-name} [overload] | static local-ip global-ip}

    no ip nat inside source {list {access-list-number | name} {pool name | interface dialer-name} [overload] | static local-ip global-ip} 

Command Description:
     To enable NAT of the inside source address, use the ip nat inside source global configuration command. 

Example:

The following portion of a show running-config translates between inside hosts addressed from either the 192.168.1.0 or 192.168.2.0 networks to the globally unique 171.69.233.208/28 network:

ip nat pool net-208 171.69.233.208 171.69.233.223 prefix-length 28
ip nat inside source list 1 pool net-208
!
interface ethernet 0
ip address 171.69.232.182 255.255.255.240
ip nat outside
!
interface ethernet 1
ip address 192.168.1.94 255.255.255.0
ip nat inside
!
access-list 1 permit 192.168.1.0 0.0.0.255
access-list 1 permit 192.168.2.0 0.0.0.255
!
ip classless
ip route 192.168.0.0 255.255.252.0 e1
ip route 0.0.0.0 0.0.0.0 e0

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