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Creating Users

In this lesson, we'll learn about why it's important to create a non root user and how to create them.

Refresher

We'll use some concepts here that was learned in the previous lesson. You can take a quick look at them to refresh them:

In the previous lesson, you would have observed that we logged in to the server using a root user. The root user is an Adminstrator which is the most privileged user on the system. This means that it has the access to modify/remove any file across all directories, create/destroy processes, modify user accounts, install software packages etc.

It's generally a bad practice to run any process as a root user unless it's required. There are some tasks in Linux that can only be performed by a root user. However, besides that kind of tasks, we should not be running anything with a root user. In case the server gets compromised, then the attacker has full access to your system and the blast radius of the attack is widened. A good thumb of rule is to follow Principle of Least Privilege to limit the blast radius in an attack. Creating a secondary, non-root user will help us achieve that.

Let's begin to do that, by adding a new user to our system:

Creating a User

Before we create a new user, first let us check what is our current user:

Viewing user ID

Using the command whoami you can view the current user:

$ whoami
root

This shows that we are currently logged in as root user.

Using adduser

Now, let us create a new user, we'll use the command adduser:

NOTE: Remember to substitute the word karan with your username in the following commands:

root@playground:~# adduser karan
Adding user `karan' ...
Adding new group `karan' (1000) ...
Adding new user `karan' (1000) with group `karan' ...
Creating home directory `/home/karan' ...
Copying files from `/etc/skel' ...
New password:
Retype new password:
passwd: password updated successfully
Changing the user information for karan
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] Y

adduser opens an interactive prompt and asks for a few basic questions:

  • Password: Type in a password that you will use to log in to this user.
  • Full Name: You can enter your full name for the system to add more details.

Rest of the details you can leave empty as they are not required. Confirm the information with Y (Yes) and you're good to go!

Granting privileges

At this moment, our user (karan in the above example) doesn't have any privileged permissions. But to self-host applications, we'll need to perform tasks like installing packages, editing system files etc. We'll need to allow our karan user to become a privileged user to perform these tasks.

That's where sudo comes in the picture. Using sudo you can become a root user and perform administrative tasks.

NOTE: Remember to substitute the word karan with your username in the following commands:

$ usermod -aG sudo karan

Perfect! We have added the user karan to a list of users who can use sudo (that list is called a sudoers file)

Accessing droplet with non-root user

In the previous lesson, we used ssh root@<ip> to access our droplet. Since we have now created another user for ourselves, we'll use that to access the droplet from now:

$ ssh karan@1.2.3.4
karan@1.2.3.4's password:
To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

karan@playground:~$

Viewing user ID

If you recall the instructions above, we used whoami to figure out which user we are currently logged in with. We'll do the same again and verify we are logged in with the other user:

$ whoami
karan

This shows that we are currently logged in as karan user.

Congrats! In this lesson, you have created a non-root user and learnt a bit about privilege escalation. In the next lesson, we'll learn how to install system packages and the concepts explained in this lesson like sudo will be used to perform some of the commands in that listen.