setupssh-7.1p1-1.exe seems to have issues on x86 (at least this system)
- Doesn't support Diffie Hellman key exchange used by PuTTY 0.66
- Was able to fix by adding KexAlgorithms setting in sshd_config
- Also had some kind of file/folder permissions or ownership issue
- Easy solution was to go back to setupssh-6.7p1-1.exe, matches good with PuTTY 0.66

ran into trouble again later with setupssh-6.7p1-1.exe and PuTTY 0.66
- Key exhange was working good thanks to debugging work above, but authentication was failing
- Looks like public key authentication was getting in the way with a seteuid() failure sometimes
- Setting PubkeyAuthentication no in sshd_config replaces it with password authentication
- Other settings that might be important: PasswordAuthentication yes, ChallengeResponseAuthentication yes
- Will this get rid of registry popups with PuTTY now?