Ubuntu – Permission denied please try again ssh error

You've locked the account.

From the manpage of usermod(8):

-L, --lock
           Lock a user's password. This puts a '!' in front of the encrypted password,
           effectively disabling the password.

Now look at your shadow line:

ubuntu:!$6$rWDSG...HSi1:15347:0:99999:7:::

Unlock it:

usermod -U ubuntu

Important note! If this user is preinstalled on the system it may be locked for a reason (security reasons), but I cannot decide that for you since this isn't a regular Ubuntu install apparently.

If the above makes you feel uncomfortable, you could create a separate user:

sudo adduser username

and answer the questions. You should be able to login just fine. Also make it able to become root (use sudo) by adding it to the sudo group:

sudo adduser username sudo

In case you need to switch to the ubuntu user on the command line, you'll have to use your elevated privileges, because you can't provide credentials for the same reason as why you can't log in using SSH. Now, log in using SSH as username, and run this to become ubuntu:

sudo su -l ubuntu

For security reasons I would not advise to use root to log in directly.

By default, the SSH server denies password-based login for root. In /etc/ssh/sshd_config, if the following line exists, possibly commented out (with a # in front):

PermitRootLogin without-password

Then change it to the following, uncommenting if needed (remove the # in front):

PermitRootLogin yes

And restart SSH:

sudo service ssh restart

Or, you can use SSH keys. If you don't have one, create one using ssh-keygen (stick to the default for the key, and skip the password if you feel like it). Then do sudo -s (or whatever your preferred method of becoming root is), and add an SSH key to /root/.ssh/authorized_keys:

cat /home/user/.ssh/id_rsa.pub >> /root/.ssh/authorized_keys