Unable to ssh localhost: Permission denied (publickey) / Connection closed by ::1 [preauth]
After reading some good manuals I realized that the public key of ubuntu@ (e.g., /home/ubuntu/.ssh/id_dsa.pub) must be added to the user’s /home/ubuntu/.ssh/authorized_keys file, which contains public keys for public key authentication) ubuntu@<localhost>:~$ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys