Securing a Linux server is one of the most important steps in protecting sensitive data, preventing unauthorized access, and ensuring system integrity. At ServerAdminz, our experts often work with enterprises and service providers to implement robust Linux server security hardening measures.
Below are five essential best practices every administrator should follow to safeguard Linux servers from potential threats.
1. Keep the System Updated
Regularly updating Linux servers ensures the latest security patches and bug fixes are applied, reducing vulnerabilities.
For Debian/Ubuntu:
sudo apt update && sudo apt upgrade -y
For CentOS/RHEL:
sudo yum update -y
Running updates frequently is the first and most effective defense against exploits.
2. Harden the Internal Firewall
A firewall acts as the first line of defense by controlling inbound and outbound traffic.
For UFW (Ubuntu/Debian):
sudo ufw default deny incoming
sudo ufw default allow outgoing
sudo ufw allow ssh
sudo ufw enable
For Firewalld (CentOS/RHEL):
sudo firewall-cmd –permanent –add-service=ssh
sudo firewall-cmd –reload
Proper firewall rules reduce the attack surface and help keep unwanted traffic out.
3. Disable Root Login and Set a Custom SSH Port
Leaving the root account accessible over SSH is a major risk. To secure your server:
Edit the SSH configuration file /etc/ssh/sshd_config and apply these changes:
PermitRootLogin no
PasswordAuthentication no
Additionally, change the default SSH port to a custom one for extra protection. This reduces automated brute-force attempts on port 22.
4. Disable Unused Services
Every unnecessary running service is a potential vulnerability. Identify active services with:
sudo systemctl list-units –type=service –state=running
Then disable and stop services not required:
sudo systemctl disable service_name
sudo systemctl stop service_name
Keeping only essential services running minimizes risks and conserves system resources.
5. Monitor Logs and System Activity
Regularly monitoring system logs helps detect unauthorized access or suspicious activity early.
For Debian/Ubuntu:
tail -f /var/log/auth.log
For CentOS/RHEL:
tail -f /var/log/secure
You can also use log monitoring tools like Logwatch for automated analysis:
sudo apt install logwatch -y
Proactive monitoring ensures security issues are caught before they escalate.
By implementing these Linux server security best practices, administrators can significantly reduce the risk of cyberattacks and strengthen overall system security. If you need to know more about linux server security, you can read our blog here.
At ServerAdminz, our team of Linux experts provides professional server hardening, monitoring, and security management services to enterprises and hosting providers worldwide. Whether you’re running Ubuntu, CentOS, or RHEL, we help you secure your infrastructure and maintain system integrity with 24/7 support.
If your organization needs expert assistance in securing Linux servers, ServerAdminz can ensure your environment stays safe, stable, and attack-resistant.
