ASA Firewall NAT - Manual NAT, Object NAT, After Auto NAT

D Prasanna Kumar Reddy · ‎04-24-2017

Hi All,

I am studying ASA concepts - NAT.

I Know ASA has three types of NAT as follows :

Manual NAT/Twice NAT - Best preferred

Object NAT/Auto NAT- Preferred after Manual NAT/Twice NAT

After Auto Manual NAT - Preferred After Object NAT/Auto NAT

I have seen few senarios where people write Manual NAT instead of Object NAT even though same function can be achieved from Object NAT/Auto NAT.

Could someone please explain why we need(Any scenarios ?) to use Manual NAT/Twice NAT & After Auto Manual NAT ?

Thanks in Advance,

Prasanna Kumar Desireddy

Murali · ‎04-25-2017

Manual NAT is very granular in nature so if you have any specific NAT requirement like if the source sub-net is going to this particular destination then do source address translation etc you can do a lot of things.

Object NAT is very convenient and easy to implement but doesn't have the granularity of Manual NAT.

Manual NAT after auto is for flexibility basically you have the power to control which NAT statement to hit.

Below link should help you to understand in detail

https://supportforums.cisco.com/document/132066/asa-nat-83-nat-operation-and-configuration-format-cli