Linux servers play a significant role in powering a large part of the internet. They run websites, applications, and business systems. Because of this, a Linux server can be a target for cyberattacks. It is evident that server security is not an option; it’s a must. A single mistake can make you lose your data, lead to downtime, and damage your reputation. Linux is secure by design. However, you need proper Linux hardening.
Linux hardening revolves around reducing attack surfaces. Its focal point is prevention, control, and monitoring. We are going to discuss essential Linux hardening tips to secure your server from cyber threats. This guide is essential for every server owner.
Let’s get started!
Regularly Upgrade Your System
Using outdated software definitely ranks among the top security risks. Cyber attackers are always on the lookout for possible vulnerabilities. Consequently, old packages are a great help to them. Keeping the system updated at all times is the way to go. Security patches should be applied immediately after their release. Use only the official repositories.
Automate updates as much as possible, but check the major changes before applying them. An updated system is your first line of defense.
Implement Stringent User and Access Policies
The root account should never be used for normal daily tasks. Set up different users with limited rights. Grant sudo access only when it is really necessary. Create strong passwords for all users. Do not use ordinary words or already reused credentials.
User accounts that are no longer in use should be deleted. Old accounts are often unmonitored and thus exploited. Access control not only limits the impact caused by an account being hacked.
Strengthen SSH Access
SSH is the primary gateway for most Linux servers. Protect it at all costs. The default SSH port makes it harder for automated attackers. Do not allow root login through SSH. Make the attackers guess both the username and the password. Go for SSH keys rather than passwords. Keys are very hard to crack.
If possible, restrict SSH access to trusted IP addresses only. These measures will significantly lower the number of brute-force attempts.
Correctly Configure a Firewall
A firewall determines what network traffic your server will accept or send out. Only those ports that are necessary should be allowed. The rest should be blocked by default. The most common open ports are SSH, HTTP, and HTTPS. Everything above that should be justified.
With the help of UFW or firewalld tools, firewall management becomes simpler. A properly configured firewall prevents many attacks from ever getting to your system.
Remove Unnecessary Services and Packages
Every service that is running poses a risk. Usually, servers have a lot of default software packages that are not in use. All these things add to the risk area. Software should be completely uninstalled if not required. Besides, there is no reason to keep running services that are unnecessary, so that is where they should be stopped and disabled.
To keep the system lean. Fewer services mean fewer vulnerabilities. It is easier to secure and monitor a minimal system.
Enforce File and Directory Permissions
Wrong permissions allow unauthorized access to sensitive data. On system files, set strict permissions. Only the users who are required should have access to it.
777 permissions should not be used. With it, anyone can read, write, and execute files. Configuration files, logs, and backups should be protected with care. The right permissions will stop privilege escalation and data leaks.
Enable Automatic Security Monitoring
You are not able to protect what is not visible to you. Install monitoring tools to track the activities that are suspicious. Logins, file changes, and the system’s behavior should be monitored. Intrusion detection systems help to identify threats at an early stage.
Logs should be reviewed regularly. Automated alerts save time and reduce the delay in response. Monitoring turns unknown threats into manageable risks.
Use Fail2Ban for Attack Prevention
Brute-force attacks are very common. Fail2Ban keeps an eye on login attempts and blocks IPs after a certain number of failures. It can be used with SSH, FTP, and web services. Though this tool doesn’t replace the firewall, it does fortify the protection. It cuts off attackers before they get in.
Secure Network Services and Ports
Scan the server for open ports. Keep ports open only that need to be kept open. All other ports will be closed. If using FTP or another unsecured protocol, switch to a secure protocol, such as SFTP, for transfer.
TLS certificates are used to encrypt data in transit. Securing a network helps mitigate data interception and unauthorized access.
Regular Backup and Disaster Recovery Plan
Security isn’t solely about defending against attacks; security also includes disaster recovery. Establishing regular backups and secure storage locations for those backups is important. Testing the backup will verify whether or not the backup is functional. A backup that isn’t tested is useless.
When an attack occurs, backup can minimize the downtime and data loss that can occur. A solid disaster recovery plan will help companies succeed in times of disaster.
Centralized Server Management
The larger the environment, the more difficult it becomes to manually manage the security of various levels of servers. Using a reputable web hosting control panel will consolidate the management of server updates, access control, firewall rules, and service monitoring into one location.
This allows for fewer opportunities for human error and provides increased speed of response. Fully centralized server management simplifies the administrative responsibility of a firm’s multiple servers.
Implement Kernel and System-Level Security
Linux comes with various security modules that can be activated on the kernel or system level. SELinux and AppArmor are examples of security modules that limit what actions applications can perform within a system.
They limit the amount of damage done when a service has been compromised. Kernel hardening options also provide additional protection against memory and privilege escalation exploits. By putting a layer of security on the system level, we provide additional protection on top of the already existing kernel-level protections.
Conduct Regular Security Audits
Security is not a one-time task; it should always be an ongoing process. Conduct regular security audits for your systems that include reviewing user access, services, logs, and system configurations.
Use trusted tools to perform vulnerability scans. When you find a vulnerability, take immediate action to fix it. With continuous improvement, your systems will be less likely to experience catastrophic events due to cyber attacks.
Conclusion
The number of cyber threats that exist in our world is increasing every year. An attacker motivated by profit can take advantage of the power and capabilities of your Linux server.
To decrease the amount of risk of your Linux servers, implement security hardening methods. Implementing security measures on a proactive basis will reduce the total cost of ownership (TCO) as opposed to waiting until a disaster happens to address these issues.
When best security practices are followed, the Linux operating system remains one of the most secure operating systems in existence. A security-hardened server protects your customer’s data and your company’s trust.
