As I was doing ssh-copy-id to transfer the key, a system alert message popped up and I screwed up the copy. Now I can neither telnet, ftp, nor ssh to the server. It just hangs.
Fortunately, the vncserver on the remote restarts on boot, so I can get into the remote to do work. But I want to fix telnet, ftp, and ssh. All three are blocked. They do not refuse the connection (no "Connection Refused" response) they just hang with no response at all. They don't even time out.
That was about 0830 this morning. It is now 1700.
Apparently my little farkling around exceeded the three failure rule and I ended up blacklisting myself.
Problem solved and, in the meantime, I've learned a lot about ssh.