Hi Dave
I have updated the libssh2 library with the latest available code on their git repository. The new code used "diffie-hellman-group-exchange-sha256" algorithm for key exchange and they also fixed some memory leak. I have verified it by putting the breakpoint in the libssh2 code, so when we called "libssh2_session_init()" it will automatically call "static int diffie_hellman_sha256(...)" function, but I don't know exactly how to identify the key exchange method (sha1 or sha256) used by the latest libssh2 library.
I have tested the pgadmin3 after updating the libssh2 library on CentOS 6.5 (64 bit) and it works fine. I have also modified the code to add human readable error message returned by the library. Attached is the patch file. Can you please review it and if it looks good can you please commit the code.
Sven, how you have identified the key exchange algorithm used by libssh2, is there any way to identify using fingerprint or key??