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In case you prefer a password protected key or you want to "hop" from system to system, SSH Agent Forwarding is helpful.

Problem analysis

The ~/.ssh directories must have 700 permissions, for example:

root@ac001.blue:~# ls -ld .ssh
drwx------ 2 root root 4096 Feb 5 10:24 .ssh

If the identity_file is not specified on the ssh command (common), has it been added to the ssh agent?  This command lists what has been added

ssh-add -l

If an identity_file has been added, is its corresponding public key in the server's ~/.ssh/authorized_keys file for the user you are trying to log in as?

If the above check list has not identified the problem, generate more information by:

• Tailing the ssh server's /var/log/auth.log file while re-trying the failing ssh command.
• Use ssh's -v option.  It can be used up to three times for greater verbosity.

Still stuck?  Update this page when you find a solution!