Creating users

When you install a new Linux system, most of the times you are only given the root account by default. While the root user gives you a lot of power and flexibility, it is also dangerous to regularly use an account which can have to much "power" due to it's privileges.

Be aware - a root user is more vulnerable to security exploits, since any commands executed under that account can affect the system’s entire filesystem.

It is a good practice to add an additional, unprivileged user to do common tasks. There might be times when you will have to create additional accounts for any other users that need access to the system. Each user should have it's own account so that their activities can be monitored and managed. The non-root users can still acquire administrative privileges, when needed, through a mechanism called sudo.

Create a new user

1. Log in to your system as the root user:

   localhost$ ssh root@<remote_ip>

2. Use the adduser command to add a new user to your system:

   # adduser newuser

3. Use the passwd command to update the new user’s password:

   # passwd newuser

   Set and confirm the new user’s password at the prompt. It is best to set a strong password:

   Changing password for user newuser.
   New password:
   Retype new password:
   passwd: all authentication tokens updated successfully.
   

4. Use the usermod command to add the user to the wheel group:

   # usermod -aG wheel newuser

   On CentOS Linux, members of the wheel group have sudo privileges by default.

5. Test the sudo access for your new user account.

   1. Using the su command, switch to the new user account:

      # su - newuser

   2. Once switched to the new user, verify that you can use sudo to run a command with superuser privileges. For example, try to list the contents of the /root directory, which is normally only accessible to the root user:

      newuser$ sudo ls -la /root

   3. The first time you use sudo in a user session, you will be prompted for the password of that user's account. You have to enter the password to proceed:

      [sudo] password for newuser:

      If the user is in the proper group and you entered the password correctly, the command that you issued with sudo will run with root privileges.