ASA NAT with multiple inside subnets

NAT can be configured on an ASA such that multiple internal subnets can be translated to a single outside IP address. Imagine the following scenario:

An ASA has two inside interfaces and a single outside interface. There are different subnets hanging off of each of those inside interfaces, and a single IP address on the outside interface. Using the following object NAT configuration, it is possible to translate both of those subnets to the single outside address like so, assuming an outside IP address of 50.50.50.10:

object-group network all_subnets network-object 192.168.0.0 255.255.255.0 network-object 10.10.10.32 255.255.255.224 object network PAT_ip host 50.50.50.10 nat (inside,outside) source dynamic all_subnet PAT_ip

This can be further scaled up by simply adding more network objects within the all_subnets object group, one for each internal subnet.

In the event that the outside address of the ASA is assigned using DHCP, take a look at this note ASA NAT with DHCP assigned IP address on the outside interface.

Links:

https://www.cisco.com/c/en/us/td/docs/security/asa/asa-cli-reference/I-R/asa-command-ref-I-R/n-commands.html#wp3072050573

https://www.cisco.com/c/en/us/td/docs/security/asa/asa84/configuration/guide/asa_84_cli_config/nat_objects.html#pgfId-1455942

https://forum.networklessons.com/t/cisco-asa-dynamic-nat-configuration/813/56?u=lagapides