Server security is the software, technologies, and practices used to secure a company's server against illegal access and other cyberattacks. It is a necessary component of the majority of system administrators and cybersecurity teams' operations.

The robust default permissions structure of Linux makes it a secure operating system. But you must still follow recommended practices to make your servers secure and efficient.

Steps to improve your Linux server's default setup, whether running Ubuntu or Debian.

1. Only Install Essentials

To safeguard your server's functioning, only install programs that your organization needs.

Standard programs like adduser and base-passwd are pre-installed on Linux server installations. Installation options include Open SSH, DNS, LAMP, and print servers.

You may also use the default package manager to add more packages. One can obtain packages from official repositories or PPAs (Personal Package Archives) maintained by Linux users.

More packages, especially from third-party repositories, mean more potential risks. Reducing the number of installed packages is essential, as is periodic purging.

2. Deactivate Root Login

Most Linux distributions feature a root user with high administrative privileges. Keep root login enabled to protect your small company cloud resources. Hackers can use this credential to get access to your server. To improve server security, deactivate this login.

To deactivate the root account, you must first establish a new user profile with elevated (Sudo) rights, so you may still install packages and conduct other admin tasks on the server. You can also grant these rights to an authorized user to guarantee safe server login.

3. Establish Two-Factor Authentication.

Two-factor authentication (2FA) increases user security by requiring a password and a second token to connect to the server.

Installing the libpam-google-authenticator package on a Debian server or a Debian-derived distribution will enable 2FA. The package can show a QR code or generate a secret token with software authentication devices like Google Authenticator or Authy.

One may use 2FA with SSH (Secure Shell) to demand secondary credentials when login in. SSH creates an encrypted text link to a remote server. These features help protect small companies from brute force login attempts and boost cloud security.

4. Promote Password Hygiene

Password hygiene is essential for anybody using a computer or SaaS program. Server administrators must also verify that users are using strong passwords. It makes them more resilient to assaults.

A. Enforcing A Minimum Cryptographic Strength

Your employees' passwords should be at least 12 characters long, with a random combination of letters, numbers, and symbols. Consider adopting a password management solution that can assess the level of security or generate a password of reasonable complexity.

B. Requiring Frequent Password Rotation

Ensure that all staff members periodically update their passwords, especially those with administrator server access.

Most Linux distributions provide a tool for changing password expiration and aging information. In addition, the software may require the user to alter their password. CLI (command-line interface) Change is one such example.

Using the -W operator, administrators may require users to update their passwords after a set number of days.

Change -W 10 daniel

After ten days, this command will compel the user 'daniel' to change their password. It may be done as bathes or login events.

5. Antivirus on the Server

Although Linux computers are immune to viruses, malware, and other cyberattacks, all Linux systems should have antivirus protection. Antivirus software improves the server's defensive capabilities.

6. Regular or Automated Updates

Old, unpatched programs pose severe risks to the OS that hackers can exploit. To avoid this, keep your server (or server pool) updated.

Many Linux distributions, including Ubuntu, update in a rolling release cycle with long-term and short-term versions. Your security professionals should decide whether they need to use bleeding edge or reliable software early on and set up update procedures accordingly.

Many Linux distributions also include tools for automating updates. For example, the unattended upgrades package for Debian will check for updates and install them remotely in the background.

7. Use A Firewall

Every Linux should have a firewall to protect it from unauthorized or malicious connections. A simple firewall (UFW) is a popular Linux firewall. You should review the firewall rules to verify it is appropriate for your organization.

DDoS attacks now pose a concern to certain operators. Web Linux servers can be protected from DDoS attacks by using a proxy service. Additionally, open-source scripts are available for installation directly on the server.

8. Create Server Backups

Things may go wrong with computers, and packages can cause dependency difficulties and other concerns. It's critical to keep the ability to reverse server modifications.

For each primary protected device, a robust backup strategy should have two copies, one offshore. System rollback tools for Linux servers simplify this procedure and speed up catastrophe recovery (DR).

Remember Safety

Linux may be the ideal server for your small or medium-sized business, as most versions come with adequate security built-in. The easiest way to protect your Linux server and reduce the possibility of unauthorized individuals gaining access is to follow the best practice guidelines.

Utilizing a server-side antivirus solution should always be a component of a multi-layered security strategy.