How to Config Initial Server Setup With Ubuntu 18.04

When you create a Ubuntu 18.04 server, you should take some steps early on as part of the basic configuration. Such steps increase the security and usability of a server and give a solid foundation for other actions.

Note: This guide shows how to manually complete the steps we recommend for new Ubuntu 18.04 servers. Following this procedure manually can be useful to learn some basic system administration skills and as an exercise to fully understand the actions being taken on your server.

Step 1 - Logging in as Root

You will need to know your server's public IP address in order to login. You will need the password (you find it by clicking on your instance) or if you installed an SSH key for authentication, the private key for the root user's account.

If you are not connected to your server, go ahead and log in as the root user using the following command (substitute the your_server_ip by instance IP).

$
ssh root@your_server_ip

Accept the prompt about host authenticity if it appears. If you are using password authentication, give your root password to log in. If you are using an SSH key that is passphrase protected, you may be prompted to enter the passphrase the first time you use the key each session. If this is your first time logging into the server with a password, you may also be prompted to change the root password.

About Root

The root user is the administrative user in a Linux environment that has very broad privileges. Because of the heightened privileges of the root account, you are discouraged from using it on a regular basis. This is because part of the power inherent with the root account is the ability to make very destructive changes, even by accident.

The next step is to set up an alternative user account with a reduced scope of influence for day-to-day work. We'll teach you how to gain increased privileges during the times when you need them.

Step 2 - Creating a New User

Once you are logged in as root, we're prepared to add the new user account that we will use to log in from now on.

This example creates a new user called sherman, but you should replace it with a username that you like:

$
adduser sherman

You will be asked a few questions, starting with the account password.

Enter a strong password and, optionally, fill in any of the additional information if you would like. This is not required and you can just hit ENTER in any field you wish to skip.

Step 3 - Granting Administrative Privileges

Now, we have a new user account with regular account privileges. However, we may sometimes need to do administrative tasks.

To avoid having to log out of our normal user and log back in as theroot account, we can set up what is known assuperuser or root privileges for our normal account. This will allow our normal user to run commands with administrative privileges by putting the word sudo before each command.

To add these privileges to our new user, we need to add the new user to the sudo group.

By default, on Ubuntu 18.04, users who belong to the sudo group are allowed to use the sudo command.

As root, run this command to add your new user to the sudo group (substitute the highlighted word with your new user):

$
usermod -aG sudo sherman

Now, when logged in as your regular user, you can type sudo before commands to perform actions with superuser privileges.

Step 4 - Setting Up a Basic Firewall

Ubuntu 18.04 servers can use the ufw firewall to make sure only connections to certain services are allowed. We can set up a basic firewall very easily using this application.

Note: If your servers are running on Let'scloud, you can optionally use own our firewall (you find it by clicking on your instance and Firewall tab) instead of the ufw firewall. We recommend using only one firewall at a time to avoid conflicting rules that may be difficult to debug.

Different applications can register their profiles with ufw upon installation. These profiles allow ufw to manage these applications by name. OpenSSH, the service allowing us to connect to our server now, has a profile registered with ufw.

You can see this by typing:

$
ufw app list

Available applications: OpenSSH

We need to make sure that the firewall allows SSH connections so that we can log back in next time. We can allow these connections by typing:

$
ufw allow OpenSSH

Afterwards, we can enable the firewall by typing:

$
ufw enable

Type "y" and press ENTER to proceed. You can see that SSH connections are still allowed by typing:

$
ufw status

Status: activeTo Action From

OpenSSH ALLOW Anywhere
OpenSSH (v6) ALLOW Anywhere (v6)

As the firewall is currently blocking all connections except for SSH, if you install and configure additional services, you will need to adjust the firewall settings to allow acceptable incoming traffic of this service.

Note: As previously mentioned, if you choose to use the Let'sCloud firewall, you can disable the ufw firewall with the command below:

$
sudo ufw stop

You need to disable UFW on startup through change for "no" on ENABLED field of /etc/ufw/ufw.conf file:

$
nano /etc/ufw/ufw.conf

Step 5 - Enabling External Access for Your Regular User

Now that we have a regular user for daily use, we need to make sure we can SSH into the account directly.

Note: Until verifying that you can log in and use sudo with your new user, we recommend staying logged in as root. This way, if you have problems, you can troubleshoot and make any necessary changes as root.

The process for configuring SSH access for your new user depends on whether your server's root account uses a password or SSH keys for authentication.

If the Root Account Uses Password Authentication

If you logged in to your root account using a password, then password authentication is enabled for SSH. You can SSH to your new user account by opening up a new terminal session and using SSH with your new username:

$
ssh sherman@your_server_ip

After entering your regular user's password, you will be logged in. Remember, if you need to run a command with administrative privileges, type sudo before it like this:

sudo command

You will be prompted for your regular user password when using sudo for the first time each session (and periodically afterwards).

To enhance your server's security, we strongly recommend setting up SSH keys instead of using password authentication. Follow our guide on setting up SSH keys on Ubuntu 18.04 to learn how to configure key-based authentication.

if the Root Account Uses SSH Key Authentication

If you logged in to your root account using SSH keys, then password authentication is disabled for SSH. You will need to add a copy of your local public key to the new user's ~/.ssh/authorized_keys file to log in successfully.

Since your public key is already in the root account's ~/.ssh/authorized_keys file on the server, we can copy that file and directory structure to our new user account in our existing session.

The simplest way to copy the files with the correct ownership and permissions is with the rsync command. This will copy the root user's .ssh directory, preserve the permissions, and modify the file owners, all in a single command. Make sure to change the highlighted portions of the command below to match your regular user's name:

$
rsync --archive --chown=sherman:sherman ~/.ssh /home/sherman

Now, open up a new terminal session and using SSH with your new username:

$
ssh sherman@your_server_ip

You should be logged in to the new user account without using a password. Remember, if you need to run a command with administrative privileges, type sudo before it like this: