// Log in to your server as the root user.
local$ ssh root@server_ip_address

// Use the adduser command to add a new user to your system.
// Be sure to replace username with the user that you want to create.
# adduser username

// Set and confirm the new user's password at the prompt. A strong password is highly recommended!
Set password prompts:
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

// Follow the prompts to set the new user's information. 
// It is fine to accept the defaults to leave all of this information blank.
User information prompts:
Changing the user information for username
Enter the new value, or press ENTER for the default
    Full Name []:
    Room Number []:
    Work Phone []:
    Home Phone []:
    Other []:
Is the information correct? [Y/n]

// Use the usermod command to add the user to the sudo group.
// By default, on Ubuntu, members of the sudo group have sudo privileges.
# usermod -aG sudo username

// add ssh keygen
- generate ssh keygen
- copy public key to authorized_keys
- reload sshd