Keep your operating system, server software, and applications up to date with the latest security patches. Regularly check for updates and apply them promptly.
Set strong, unique passwords for all user accounts, including the root account. Consider using a combination of uppercase and lowercase letters, numbers, and special characters.
Disable root login via SSH and use a non-standard port. Utilize SSH keys for authentication instead of passwords and restrict SSH access to specific IP addresses if possible.
Implement a firewall to control incoming and outgoing traffic. UFW (Uncomplicated Firewall) or iptables are common choices and only open necessary ports and services.
Regularly audit your server's security settings and logs. Look for any unusual activities or unauthorized access attempts.