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Maybe a UDP hole?

I’m trying to find out if punching UDP holes for a specific NAT is possible, but I found that when the computer behind the NAT sends UDP packets to two different IP addresses on the same port, being connected to the same port, NAT assigns two different external port numbers. So what is behind this particular NAT, I believe that punching UDP holes is not possible, is that correct?

thanks

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Not necessary. The router may accept IGD .

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This means that your NaT is Symetric, and if your NaT is Symetric, it gives different external ports for each connection. And it is impossible to connect the hole on both sides, but you can still connect p2p. But it is only possible if the intermediary side uses Nat. Find it.

But if in two places where Symetric NaT is used, there is no way to connect a p2p connection with Udp Hole Punching.

  • a: Symetric => b: symetric ---- impossible
  • a: Conic => b: Conic ------------ possibly easy
  • a: Symetric => b: Coinc --------- possible / only one-way handshake 4: a: Conic => b: symetric --------- impossible / but it is possible to connect a one-way handshake

But you can still use port prediction methods. this means that you have to guess which port can be used in communication and try to connect it (Tcp Hole Punch)

For Conic NaT, you can learn about punching UDP holes. Please check the sample at https://github.com/turapulku/NaT-Traversal-UDP-Hole-punch.git

It is still developing, but for now I hope it will be useful

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You can use this website to confirm the behavior of this particular NAT.

http://nattest.net.in.tum.de/test.php

It will check your NAT type and see if UDP / TCP hole punching is possible.

But since you already knew that the port assignment is random, punching UDP holes is not possible. Using UPnP is another way, but does not work for nested NATs.

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