How to determine the type of NAT behind which is your own computer?

Question

Network administration

I want to write a myNATtype()
function that would return one of the following responses:
Full Cone NAT, Symmetric NAT, Address Restricted NAT, Port Restricted NAT, or
Some Other Unknown F_cking NAT (no NAT)
How can I do this?

Answer 1

You can't tell the difference between a conical nut and a static nut. They will read Wikipedia, and then they will achieve all sorts of heresy on the porches .

Answer 2

teredo clients define the nat type to determine their teredo address. read about this protocol and use their servers to detect your type

Answer 3

using the STUN protocol, you can determine the type of nat, see the client example github.com/jselbie/stunserver/blob/master/client/clientmain.cpp