This trick (ping 3.3.3.3) is used to let a server behind NAT learn the IP address of a client that is also behind NAT, without requiring any non-NAT server (such as https://ifconfig.co).
The main action of this tool is to then create a UDP tunnel between the client and server.
But based on quick reading, the tool appears to assume that the NAT does not rewrite the UDP source port, so it won't work on all routers. STUN (which is used in e.g. WebRTC) implements more sophisticated techniques, and even then there are some cases where it cannot work and the only option is to use a relay (TURN).
I'm pretty sure that the same issue applies to the ping 3.3.3.3 trick -- if the NAT rewrites the ping identifier (as described in the article), the trick would break.
This trick (ping 3.3.3.3) is used to let a server behind NAT learn the IP address of a client that is also behind NAT, without requiring any non-NAT server (such as https://ifconfig.co).
The main action of this tool is to then create a UDP tunnel between the client and server.
But based on quick reading, the tool appears to assume that the NAT does not rewrite the UDP source port, so it won't work on all routers. STUN (which is used in e.g. WebRTC) implements more sophisticated techniques, and even then there are some cases where it cannot work and the only option is to use a relay (TURN).
I'm pretty sure that the same issue applies to the ping 3.3.3.3 trick -- if the NAT rewrites the ping identifier (as described in the article), the trick would break.