Overview of NAT Transformation

NAT terminology

Inside local address (inside local address):

A device in an Inside network, the IP address of the Inside, that is, the actual address of the internal host

Inside global address (inside global address):

A device in an Inside network that is the IP address of the Outside, that is, the address where the internal host is translated by NAT to the outside

Outside local address (outside local address):

A device in an Outside network, the IP address of the Inside, that is, the address of the external host translated by the NAT device

Outside global address (outside global address):

A device in an Outside network, the IP address of the Outside, that is, the real address of the external host

NAT is divided into: static NAT, dynamic NAT, port NAT (PAT port reuse).

Static NAT is an one-to-one translation, that is, a local area network IP address corresponds to a public network IP address, which makes little sense but is just a bit more secure.

Dynamic NAT refers to one-to-many or many-to-many translation, which cannot be translated at the same time. When the client accesses outward, it polls the public network address in the address pool, but any local area network IP address can be translated when the public network IP address is idle.

Port PAT is a many-to-one or many-to-many translation that can be translated at the same time. By adding port numbers, multiple private IP addresses can be translated at the same time and applied to the port.

.