So, if you're running into the "I have an authentication key all set why won't it work right" and you've gone through all the helpful suggestions like "make sure permissions" and "check sshd config", one last thing to check would be what you named your private key when you ran ssh-keygen.

If you named it something other than the default prompted filename, you need to use the -i switch when trying to ssh so it will know where to look. So try

ssh -i /path/to/your_clever_filename user@hostname


You're welcome.