Quick Guide To Linux Server Security Best Practices

BySalvador

Protect Your Business. Fortify Your Future.

In today’s digital battlefield, your Linux server is more than a machine—it’s your kingdom’s gatekeeper. Whether you’re running a simple website, a powerful cloud application, or a global infrastructure, Linux server security isn’t optional. It’s mission-critical.

This quick guide reveals actionable best practices you can implement right now to shield your servers, protect sensitive data, and maintain customer trust. It’s not about paranoia—it’s about power, control, and peace of mind.

Let’s lock it down.

1. Keep Your System Updated

Security starts with the basics. An outdated system is a playground for hackers. Always keep your packages, kernel, and libraries up to date. Set up automatic security updates for real-time protection or build a manual update routine into your weekly schedule.

sudo apt update && sudo apt upgrade -y   # Debian/Ubuntu
sudo yum update -y                       # CentOS/RHEL

🔥 Pro Tip: Subscribe to security mailing lists of your distro to stay ahead of zero-day vulnerabilities.

2. Use SSH Keys, Not Passwords

Passwords can be brute-forced. SSH keys are exponentially more secure. Replace password-based logins with public-private key authentication.

Steps:

  • Generate your key pair: ssh-keygen
  • Add your public key to /home/user/.ssh/authorized_keys
  • Disable password login in your SSH config:
sudo nano /etc/ssh/sshd_config
# Change the following lines:
PasswordAuthentication no
PermitRootLogin no

Then reload SSH:

sudo systemctl reload sshd

🌱 Bonus: Use Fail2Ban to protect against repeated failed login attempts.

3. Minimal Install. Minimal Risk.

Install only what you need. Every unnecessary package is a potential security hole. A lean system is a clean system.

Use tools like:

deborphan    # to find orphaned packages
ufw status   # to check open ports and services

💡 Mindset Shift: Think of software as doors. Fewer doors = fewer entry points for attackers.

4. Activate and Configure Your Firewall

Your firewall is your first line of defense. Tools like UFW (Uncomplicated Firewall) or firewalld offer powerful protection with minimal setup.

For UFW:

sudo ufw default deny incoming
sudo ufw default allow outgoing
sudo ufw allow OpenSSH
sudo ufw enable

🛡️ Best Practice: Only open ports that are absolutely necessary. Shut down everything else.

5. Enforce the Principle of Least Privilege

Every user and process should have only the permissions they absolutely need.

  • Avoid running applications as root.
  • Use sudo for elevated privileges.
  • Audit and remove unused users.
  • Use visudo to define secure, restricted privilege escalation.
sudo adduser deployer
sudo usermod -aG sudo deployer

🚨 Danger Zone: A single careless chmod 777 can expose your entire system. Don’t do it.

6. Use Intrusion Detection Systems (IDS)

Detect threats before they cause damage with tools like AIDE (Advanced Intrusion Detection Environment) or Tripwire. These tools monitor filesystem changes and send alerts when unauthorized modifications occur.

Example AIDE setup:

sudo apt install aide
sudo aideinit
sudo cp /var/lib/aide/aide.db.new /var/lib/aide/aide.db

🔔 Alerting = Awareness = Action. Always be the first to know.

7. Enable and Monitor Logs

Logging is your rearview mirror. You can’t fix what you can’t see.

  • Activate auditd, rsyslog, or journalctl
  • Log SSH sessions
  • Review logs regularly or use a log monitoring solution like Logwatch, Logrotate, or Graylog
sudo journalctl -xe

🧠 Tip: Automate alerts for suspicious activity with simple cron jobs or integrate with SIEM systems.

8. Secure Your Web Server & Applications

If your Linux server hosts web services, harden your web stack:

  • Disable unnecessary Apache/Nginx modules
  • Enforce HTTPS with Let’s Encrypt
  • Use security headers (Content Security Policy, X-Frame-Options, etc.)
  • Isolate apps with containers (Docker, Podman) or VMs

🔒 Isolation = Damage Control. If one app is compromised, it doesn’t take down the rest.

9. Backups. Backups. Backups.

A secure system without backups is a house of cards. Use automated, encrypted, off-site backups and test them regularly.

Recommended tools:

  • rsync
  • borgbackup
  • restic
  • Cloud solutions (e.g., Swiss Backup by Infomaniak)

🧩 Golden Rule: 3 copies, 2 different formats, 1 offsite. Follow the 3-2-1 backup strategy.

10. Regularly Audit Your System

Security is not a one-time setup. It’s a living, breathing discipline.

Run regular security audits using:

  • lynis
  • chkrootkit
  • rkhunter
  • clamav
sudo apt install lynis
sudo lynis audit system

✅ Actionable Reports = Real Results.

BONUS: Automate Everything

Leverage cron, Ansible, or shell scripts to automate repetitive tasks. Automation ensures consistency, reduces human error, and boosts your efficiency.

Examples:

  • Automated updates
  • Log backups
  • Intrusion scan reports
  • SSL certificate renewal

🤖 Automation = Scalable Security. Your system protects itself—while you sleep.

Final Thoughts: Security Is a Culture

You don’t need to be a cybersecurity wizard to keep your Linux server safe. You just need to adopt the right habits, follow the best practices, and stay vigilant. In the end, security is not a product—it’s a process.

At Levantem, we help you build bulletproof Linux infrastructures, custom-fit to your unique business model. Whether you’re launching your first server or scaling your infrastructure worldwide, we’re here to guide and protect.

🔐 Ready to Fortify Your Linux Server?

Book a free consultation today and let’s bulletproof your system—together.
👉