Full-cone NAT is not detected

[HardenedSteel]

I tried I2Pd on both full-cone NAT and port restricted cone NAT but I2Pd always reports NAT type as symmetric NAT.

[orignal]

It means the peer always sees different port, than assigned.

[HardenedSteel]

This shouldn't be the case for full-cone NAT AFAIK.

Other tools reports full-cone NAT but i2pd differs, is this expected behavior?

[orignal]

Then please tell how it should be done properly.
https://github.com/PurpleI2P/i2pd/blob/openssl/libi2pd/SSU2Session.cpp#L1832-L1841

[HardenedSteel]

The current logic only seems to compare the result from a single peer. The logic should compare the port number from the results obtained from multiple peers to check if it remains the same or changes.

With this we can detect if the NAT is cone (when same) or symmetric (when changes).

A tool for detecting NAT type: https://github.com/pion/stun/tree/master/cmd/stun-nat-behaviour