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Basic Server Setup with Ubuntu 18.04


When you first create a new Ubuntu 18.04 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.

Logging in as Root
To log into your server, you will need to know your server's 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 are not already connected to your server, go ahead and log in as the root user using the following command (replace the highlighted portion of the command with your server's 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.

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 peter, but you should replace it with a username that you like:

    adduser peter

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.

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 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 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 peter

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

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.

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

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.

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 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 peter@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.

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=peter:peter ~/.ssh /home/peter

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

    ssh peter@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).

Wrapping up
At this point, you have a solid foundation for your server. You can install any of the software you need on your Ubuntu 18.04 server now.

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