NewUser=winston
sudo useradd $NewUser --create-home
sudo mkdir /home/$NewUser/.ssh
sudo touch /home/$NewUser/.ssh/authorized_keys
sudo chown -R $NewUser:$NewUser /home/$NewUser/.ssh
sudo chmod 700 /home/$NewUser/.ssh
sudo chmod 600 /home/$NewUser/.ssh/authorized_keys
Add your pubkey
sudo nano /home/$NewUser/.ssh/authorized_keys
Edit sshd_config to add ALL users that can SSH into your machine
sudo nano /etc/ssh/sshd_config
AllowUsers ubuntu winston
sudo service ssh reload