How to Secure Linux: Create a Sudo User and Disable Root SSH Login

Background

For security reasons, root login via SSH should be prohibited.

After disabling root SSH login, a privileged user is needed for remote access.

Create a user with sudo privileges

Create a normal user "rain"

useradd command creates a user; -m creates a home directory, -c adds a comment.

useradd -m -c "Normal User" rain

Set a password for the user

Password should be at least 8 characters, include upper‑ and lower‑case letters, numbers, special symbols, and must not contain the username.

passwd rain

Add the user to the admin group

usermod modifies user settings; -aG appends the user to a group. On CentOS/RHEL the wheel group has sudo rights, while on Debian/Ubuntu the sudo group does.

usermod -aG wheel rain

Disable root SSH login

Switch to the privileged user

su rain

Edit the sshd_config file

Even though root can edit the file, using the sudo‑enabled user ensures the changes are made with proper privileges.

sudo vi /etc/ssh/sshd_config

Set PermitRootLogin to no .

PermitRootLogin no

Restart the SSH service

After saving the file, restart the service to apply changes. Older systems may use sudo service sshd restart .

sudo systemctl restart sshd

Test root login

The login attempt fails with the same response as an incorrect password, confirming that root SSH access is disabled.