pwnat nat traversal, manipulation of UPNP a lot of ways very different.
Everyone uses a more suitable option.
In any case, there is a server with the white address connected both the client sitting behind NAT'om coordinating their actions, and eventually they establish a direct connection and begin to send traffic directly, without resorting to this server.
the official way
What is the official way absolutely incomprehensible.
NAT is just a technology, no official status is not available.
There are other technologies allowing to work with clients behind NAT, that's all.