NAT type judgment

This article gives the NAT type judgment code

Cone NAT or symmetric NAT

The concrete implementation block diagram is as follows: If Server A and Server B return to the client PORT1 and PORT2 equal, then the NAT is cone NAT, otherwise symmetric NAT.

Is full Cone NAT?

The concrete implementation block diagram is as follows: If client can receive data returned by Server B, Nat is full Cone nat.

ip-restricted Cone Nat or port-restricted Cone NAT

The concrete implementation block diagram is as follows: If client can receive data returned by Server A, NAT is ip-restricted Cone NAT, otherwise port-restricted Cone Nat.

NAT type judgment