I use PuTTY, and I use a key generated with PuTTYgen. My server is a VPS running Ubuntu 14.04 (perhaps this belongs on askubuntu, but I think it may not be Ubuntu specific). The public portion of the key is in ~/.ssh/authorized_keys on my server account. The private key is on my PC and not pass-phrase protected.I attempted to connect to my server after a few days, and received server refused our key. I immediately tried again with success.The following is in /var/log/auth.log (The POSSIBLE BREAK-IN ATTEMPT message is normal, I know that's not a flag):Apr 20 21:10:08 blue sshd[6332]: reverse mapping checking getaddrinfo for my_host [my_ip] failed - POSSIBLE BREAK-IN ATTEMPT!Apr 20 21:10:17 blue sshd[6332]: Connection closed by my_ip [preauth]Apr 20 21:10:28 blue sshd[6334]: reverse mapping checking getaddrinfo for my_host [my_ip] failed - POSSIBLE BREAK-IN ATTEMPT!Apr 20 21:10:28 blue sshd[6334]: Accepted publickey for steve from my_ip port 55185 ssh2: RSA key_signature_I_thinkApr 20 21:10:28 blue sshd[6334]: pam_unix(sshd:session): session opened for user steve by (uid=0)Apr 20 21:10:28 blue sshd[6334]: pam_systemd(sshd:session): Failed to create session: No such file or directoryCould this be a man in the middle? A bug in PuTTY? Is this common? I would not expect it to fail since TCP is pretty solid.What would cause this behavior?Note: My VPS setup: After the server was initialized new on the VPS, I set up key based encryption, battened down sudo a little, moved sshd to a different port. I set up my .bashrc to start tmux. Nothing special. The server has been running for a few weeks doing not much of anything. Before I moved sshd, I got quite a few connections (none supposedly successful), but after nothing but my own logins. And then the event in the question happened.
Why would my putty key be refused server refused our key, but works on next attempt?
login;sshd;putty;key authentication;puttygen