When learning about NAT you might hear a few terminologies thrown about that might confuse you.

Let’s look at a Map

Inside Local

• Inside local is a private address space say 192.168.1.X /24.  It’s behind a router that has NAT enabled.

Inside Global

• While this is called Inside it really is an “outside” or public address. This is the interface of the router that has a public ip address and is what all computers in the Inside Local area are translated through.

Outside Global

• This is the term given to the External IP address that you might want to communicate with. It has an external IP address similar to the “Inside Global”. This will be the address that hides the “outside local” address range (ie. 192.168.2.X)

Outside Local

• Typically you will never know this address range since it is hidden from your network because of Nat. Similarily your inside local will be the “outside local” for the other network and it will never know your internal IP address range.