Initial Server Setup with Debian 10

Introduction

When you first create a new Debian 10 server, there are a few configuration steps that you should take early on as part of the basic setup. This will increase the security and usability of your server and will give you a solid foundation for subsequent actions.

In this tutorial, we will learn how to log into our server as the root user, create a new user with admin privileges, and set up a basic firewall.

Step 1 — Logging in as Root

To log into your server, you will need to know your server’s public IP address. You will also need the password or, if you installed an SSH key for authentication, the private key for the root user’s account. If you have not already logged into your server, you may want to follow our guide on how to connect to your Droplet with SSH, which covers this process in detail.

If you are not already connected to your server, go ahead and log in as the root user using the following command (substitute the highlighted portion of the command with your server’s public IP address):

ssh root@your_server_ip

Accept the warning about host authenticity if it appears. If you are using password authentication, provide 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. Later, we’ll explain how to gain increased privileges for those 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 sammy, but you should replace it with a username that you like:

adduser sammy

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 you would like. This is not required and you can just hit ENTER in any field you wish to skip.

Next, we’ll set up this new user with admin privileges.

Step 3 — Granting Administrative Privileges

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

To avoid having to log out of our normal user and log back in as the root account, we can set up what is known as superuser 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 the command.

To add these privileges to our new user, we need to add the new user to the sudo group. By default, on Debian 10, 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 sammy

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

Step 4 — Setting Up a Basic Firewall

Debian servers can use firewalls to make sure only certain connections to specific services are allowed. In this guide, we will install and use the UFW firewall to help set firewall policies and manage exceptions.

We can use the apt package manager to install UFW. Update the local index to retrieve the latest information about available packages and then install the UFW firewall software by typing:

apt update
apt install ufw

Firewall profiles allow UFW to manage named sets of firewall rules for installed applications. Profiles for some common software are bundled with UFW by default and packages can register additional profiles with UFW during the installation process. OpenSSH, the service allowing us to connect to our server now, has a firewall profile that we can use.

You list all available application profiles by typing:

ufw app list

Output
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

Output
Status: active

To             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 traffic in. You can learn some common UFW operations in our UFW essentials guide.

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.

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 sammy@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_to_run

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 Debian 10 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 with the cp command. Afterwards, we can adjust ownership of the files using the chown command.

Make sure to change the highlighted portions of the command below to match your regular user’s name:

cp -r ~/.ssh /home/sammy
chown -R sammy:sammy /home/sammy/.ssh

The cp -r command copies the entire directory to the new user’s home directory, and the chown -R command changes the owner of that directory (and everything inside it) to the specified username:groupname (Debian creates a group with the same name as your username by default).

Now, open up a new terminal session and log in via SSH with your new username:

ssh sammy@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:

sudo command_to_run

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

Where To Go From Here?

At this point, you have a solid foundation for your server. You can install any of the software you need on your server now.