Adding a New User¶

Introduction¶

Adding users in Linux is a fundamental system administration task.
For security reasons, it is not recommended to work in Linux directly as the root user, as even a minor mistake in a command can lead to irreversible damage to the system or critical files.
A safer and more appropriate approach is to create a separate regular user (for example, vdsuser) and grant them the ability to run administrative commands via sudo. This allows root‑level tasks to be performed only when necessary, maintaining protection against accidental or malicious actions.

Creating a sudo User¶

There are several ways to add a user, but the most common commands are useradd and adduser.

Connect to your server via SSH
```
ssh root@ip_address
```
Create a new user
```
adduser vdsuser
```
On Ubuntu/Debian, you will then be prompted to set the user’s password immediately. Enter it twice; note that the characters are not displayed as you type.

On CentOS, to set the password you need to run:
```
passwd vdsuser
```
Then, on Ubuntu/Debian, provide additional user information (you can leave fields blank).
Grant the user sudo privileges by adding them to the sudo group

On Ubuntu/Debian, run:
```
usermod -aG sudo vdsuser
```
On CentOS, run:
```
usermod -aG wheel vdsuser
```
Verify that the user can use sudo

Switch to the new user’s session:
```
su - vdsuser
```
Run a command with sudo privileges (for example, list the /root directory):
```
sudo ls -la /root
```
If the directory contents appear, the configuration is correct.

Adding a User Using an SSH Key¶

If your server uses an SSH key, password-based login is disabled. To allow a new user to log in successfully, copy your local public key (~/.ssh/authorized_keys) into the new user’s account.

Copy the entire .ssh directory into the new user’s home
```
cp -r ~/.ssh /home/vdsuser
```
Set vdsuser as the owner of that directory using chown
```
chown -R username:vdsuser /home/vdsuser/.ssh
```
After completing the above steps, connect to the server using the SSH key
```
ssh <vdsuser>@<ip_address>
```

Note

For Added Security, Disable Remote Access for the Root User

Open the file /etc/ssh/sshd_config.
Change the PermitRootLogin setting to no.
Press Ctrl‑x, then y, then Enter to save changes and exit the editor.
Restart the SSH service:

On Ubuntu/Debian:

sudo service ssh restart

On CentOS:

sudo service sshd restart

Useful User Management Commands¶

Basic User Management Commands¶

Get user information
```
id username
```
Change a user’s password
```
passwd username
```
Add a user to a group
```
usermod -G group_name username
```
Change a user’s primary group
```
usermod -g group_name username
```
Change a user’s home directory (note: the flag may vary by distribution)
```
usermod -g group_name username
```
View all created users
```
cat /etc/passwd
```
List all users in the system
```
w
```
Delete a user
```
deluser username
```

Basic Group Management Commands¶

Create a group
```
groupadd group_name
```
Delete a group
```
delgroup group_name
```