Create New User

adduser ubuntu
usermod -aG sudo ubuntu
cd /home/ubuntu/
mkdir .ssh
chmod 700 .ssh
chown ubuntu:ubuntu .ssh
cp -a /root/.ssh/authorized_keys . #or make a new key
chmod 600 authorized_keys
chown ubuntu:ubuntu authorized_keys

# Can update password:
passwd ubuntu
# Can delete password:
passwd -d ubuntu

# backup /etc/ssh/sshd_config now
# if it doesn't work, set these properties in /etc/ssh/sshd_config:
# commented out options show the defaults, e.g. #UsePAM yes
UsePAM no
AuthorizedKeysFile      %h/.ssh/authorized_keys
PubkeyAuthentication yes
PasswordAuthentication no
ChallengeResponseAuthentication no

service ssh restart

# Make sure the correct shell is set for the user here:
nano /etc/passwd