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Cisco ASA Series Firewall CLI Configuration Guide
 
Chapter 9      Network Address Translation (NAT)
  History for NAT
Automatic NAT rules to translate a VPN peer’s 
local IP address back to the peer’s real IP 
address
8.4(3) In rare situations, you might want to use a VPN peer’s real 
IP address on the inside network instead of an assigned local 
IP address. Normally with VPN, the peer is given an 
assigned local IP address to access the inside network. 
However, you might want to translate the local IP address 
back to the peer’s real public IP address if, for example, 
your inside servers and network security is based on the 
peer’s real IP address.
You can enable this feature on one interface per tunnel 
group. Object NAT rules are dynamically added and deleted 
when the VPN session is established or disconnected. You 
can view the rules using the show nat command.
Because of routing issues, we do not recommend using this 
feature unless you know you need it; contact Cisco TAC to 
confirm feature compatibility with your network. See the 
following limitations:
• Only supports Cisco IPsec and AnyConnect Client.
• Return traffic to the public IP addresses must be routed 
back to the ASA so the NAT policy and VPN policy can 
be applied.
• Does not support load-balancing (because of routing 
issues).
• Does not support roaming (public IP changing).
We introduced the following command: 
nat-assigned-to-public-ip interface (tunnel-group 
general-attributes configuration mode).
NAT support for IPv6 9.0(1) NAT now supports IPv6 traffic, as well as translating 
between IPv4 and IPv6. Translating between IPv4 and IPv6 
is not supported in transparent mode.
We modified the following commands: nat (global and 
object network configuration modes), show nat, show nat 
pool, show xlate.
NAT support for reverse DNS lookups 9.0(1) NAT now supports translation of the DNS PTR record for 
reverse DNS lookups when using IPv4 NAT, IPv6 NAT, and 
NAT64 with DNS inspection enabled for the NAT rule.
Feature Name
Platform 
Releases Description