What is Linux security?
Linux security ensures the confidentiality, integrity, and availability of Linux-based systems and protects them from hackers, brute-force attacks, and other cyber threats. A secure Linux system necessitates a combination of tools, best practices, and configurations to safeguard the system and data—all of which we’ll cover in this article. But first, let’s look at some important context to see how Linux fits into your overall cloud security strategy.
Why is Linux security important?
Linux stands out as a secure operating system by design, and its open-source nature is a key reason why. Because code is constantly being worked on by a large number of people and problems are quickly identified, Linux is a powerful OS for virtually any application—from desktops to servers to embedded systems.
On the other hand, the same openness requires users to be rigorous about applying security patches and updates to keep vulnerabilities from being exploited. And considering Linux is used by many organizations to store and manage essential data, it requires more than mere updates to stay protected from threats. Tailored and effective protective measures must be employed to prevent unauthorized access, data leakage, or loss of confidential information. (These security measures also maintain adherence to critical regulations such as GDPR and HIPAA.)
When it comes to Linux security, the stakes are higher than configurations at just one enterprise. Because Linux powers most of the internet's infrastructure, including web servers, databases, and cloud platforms, Linux security is pivotal for a secure internet. Let’s take a closer look at how to make the most of Linux while keeping your systems safe.
The top 8 best practices for Linux security
1. Efficient user management
Proper user management greatly reduces the risk of unauthorized access and makes sure that users have only the permissions required for their specific roles. A few methods to achieve this goal are:
Centralized authentication systems: Centralized authentication systems like OpenLDAP facilitate the management of user identities and access rights. With centralized authentication, administrators can manage users’ accounts, security policies, and access control for all systems and applications. This approach not only increases security but also decreases the problems that arise from maintaining several user databases.
The principle of least privilege: The principle of least privilege is a key security concept that says users should be given only the minimal level of access required to perform their tasks. Adhering to this principle significantly reduces the risk of malicious or accidental actions that could jeopardize system security.
Strong authentication: Implementing strong authentication policies is another crucial aspect of user management. Set strong passwords by making them long, and make sure each password contains a mix of letters, numbers, and special characters. By regularly resetting passwords, you reduce the risk of exposed passwords being used.
Multi-factor authentication: MFA can enhance security by adding an extra layer of protection. This can be achieved by requiring users to provide additional verification, such as a code sent by text message or a phone call confirming their activity.
User-activity monitoring: Continuously monitoring user activity pays off: You instantly detect any unusual behavior and can respond to threats before they turn into full-blown security incidents. There’s a wide range of logging tools available that are capable of tracking user actions, including file access, login attempts, and command execution. Regularly review these logs to look for patterns of suspicious behavior and take necessary actions to reduce risks.
2. Regularly update the operating system and software package
As previously mentioned, keeping the operating system and software packages up-to-date is a vital step in Linux security. Regular updates protect against known vulnerabilities and provide the latest security and performance improvements.
One of the most important best practices for Linux security is to configure your system to automatically apply critical security updates. Many Linux distributions offer tools and settings to enable automatic updates. For example, you can use unattended-upgrades on Debian-based systems or dnf-automatic on Fedora-based systems. Automated updates minimize the risk of human error and ensure that patches are applied as soon as they’re available.
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3. Encrypt and secure file systems
Encryption ensures that even if someone manages to physically access your data storage, the data itself will remain unreadable and confidential. Take advantage of the security measures listed below to prevent unauthorized access and tampering:
Full-disk encryption: Full-disk encryption (FDE) protects all data stored on a system by encrypting the entire storage and external devices. Tools like LUKS (Linux Unified Key Setup) and dm-crypt are commonly used for FDE on Linux systems. LUKS provides a standardized encryption format, making it easier to manage and keeping everything compatible across different distributions. FDE is especially important for devices that are more susceptible to physical theft or loss.
Sensitive files and directories encryption: While FDE protects the entire disk, there may be scenarios where encrypting specific files or directories is more appropriate. Tools like GNU Privacy Guard (GnuPG) can be used to encrypt individual files, ensuring that only authorized users with the right decryption key pair can access the data. This approach is useful for protecting highly sensitive information (think financial records or personal data) within a larger system.
Access control lists (ACLs): Linux supports access control lists (ACLs) for fine-grained control over file permissions. ACLs are used to provide administrators a way to set permissions for multiple users and groups in order to limit access to individual files and directories, enabling precise control over who can read, write, or execute specific files.
4. Secure and monitor networks
Securing and monitoring networks is a vital step in protecting Linux systems from external threats and ensuring secure communication. To strengthen your network security and increase visibility, follow these best practices:
Implement firewalls: Firewalls are used to control incoming and outgoing traffic based on a set of predefined rules. Linux tools like iptables and firewalld can be utilized to configure and manage firewall rules on Linux systems.
Prioritize Secure Shell (SSH) security: SSH service is used for securing remote access, and there are several measures you can take to strengthen the security of SSH. Using SSH certificates for the authentication process rather than SSH keys adds another layer of security and gives you more flexibility: Certificates do not require the use of multiple keys and in case of compromise, all certificates issued can be revoked.
Monitor networks: Continuous network monitoring is a crucial step for detecting and responding to potential security threats. Many tools offer comprehensive monitoring capabilities, including Nagios and Zabbix.
Secure wireless networks: Securing wireless networks involves several practices, such as using strong encryption methods.
It’s a good idea to use a native agent that has the ability to monitor network communications in order to identify new communication with external malicious domains. The agent can leverage eBPF to analyze the network traffic at the kernel level in real time and notify the user about suspicious activity, significantly strengthening your security.
Use virtual private networks (VPNs): VPNs are used for protection during transit by providing secure and encrypted communication over the internet, preventing interception and tampering. OpenVPN and WireGuard are some of the most well-known VPN solutions for Linux systems.
5. Back up everything
Regular backups of Linux systems are a crucial plank of any disaster recovery plan, protecting data and ensuring its availability in the event of a security breach or system failure. Take advantage of these tools and strategies to streamline your backup processes.
Automated backups: Automating the backup process ensures consistent data protection without requiring manual work. Tools like rsync, Bacula, and Amanda are commonly used for automating backups on Linux systems.
Offsite storage: Keeping backups offsite protects data from disasters such as floods or fires. Remote servers, cloud storage services, and physical media stored at various locations are scalable and secure options for offsite backups.
Backup integrity: Encrypting backups prevents sensitive data from being accessed by unauthorized parties both while stored and during transmission. Tools like BorgBackup and Duplicity offer built-in encryption options for securing your backups.
Versioning and retention policies: Implementing versioning and retention policies manages backup storage and keeps historical versions of data available for recovery. Solutions like restic and Duplicati support versioning and retention policies.
Backup monitoring and alerts: Monitoring the backup process and configuring alerts for failures or issues builds reliability into your systems. Monitoring tools like Nagios and Zabbix track backup status, performance, and storage usage.
6. Secure Linux configurations
Securing Linux configurations is essential for hardening your operating system and applications, minimizing vulnerabilities, and enhancing overall security. Follow these tips to secure your configurations:
Implement security policies with SELinux and AppArmor: SELinux and AppArmor are two security modules in Linux that implement mandatory access control (MAC) security policies. SELinux applies a set of rules to define what an application is allowed to do, effectively restricting its operation to prevent the spread of security threats. AppArmor offers a lighter-weight, profile-based method of putting limits on what programs can do. Both tools minimize the chances of exploits and unauthorized operations, since the programs are run with the minimum level of privileges required for their work.
Minimize installation: Installing only necessary software and services greatly reduces your attack surface. During the installation process, avoid selecting optional packages and components that you don’t need.
Leverage configuration management: Configuration management simplifies the process of maintaining secure settings, applying updates, and complying with security standards. Tools like Ansible, Puppet, and Chef automatically apply secure settings and maintain compliance across systems.
Keep an eye on file permissions and access control: Setting strict file permissions prevents unauthorized access and modifications to Linux systems. Tools like chmod and chown can be used to manage file permissions so that only authorized users have access to particular files and directories.
Secure your service configurations: Configure services with security in mind. Disable or remove unnecessary services to reduce potential entry points. Configure web servers to use HTTPS, limit access to administrative interfaces, and disable directory listings.
7. Enable logging and monitoring
Logging and monitoring on Linux systems allows you to gain visibility into system activities, detect potential security incidents, and adhere to security policies.
Enabling comprehensive logging involves capturing logs from various sources:
System logs capture logs that are related to system events, such as boot processes, hardware changes, and kernel messages. Tools like journalctl and dmesg provide access to system logs.
Application logs are designed to capture logs produced by applications and services operating on the system. (Applications must be configured to log relevant events and errors.)
Security logs capture logs related to security activity and events, such as access control changes, authentication attempts, and firewall activities. Tools like the audit daemon (auditd) provide detailed security logs and audit trails.
Network logs capture logs related to network activities, such as connections, traffic patterns, and intrusion detection alerts. Snort and Suricata are two options for network monitoring and logging.
8. Stay vigilant with ongoing training and awareness
Insight into the latest security trends, vulnerabilities, and Linux security best practices is crucial for proactive security management. Subscribing to security mailing lists, following relevant forums, and reading security blogs and publications help administrators stay on top of emerging threats and mitigation techniques.
One of the best ways to keep up with security trends is by scheduling regular security training programs for all users and administrators. Training should cover topics like the signs of a phishing attack, password management tips, safe browsing practices, and best practices and protocols to protect software. For administrators, include advanced topics like Linux hardening, network security, and incident response.
Conclusion
It’s a simple fact: Linux security is an ongoing process that requires continuous improvement. Regularly reviewing security practices, policies, and training programs helps identify opportunities to add new security measures and ensures that existing security measures remain effective.
The Wiz Runtime Sensor can be deployed on Linux hosts to give you the best visibility, risk assessment, and real-time protection and threat detection—all on a single platform. With the Wiz Runtime Sensor and Wiz platform, you gain a comprehensive view of your cloud infrastructure’s security posture. It continuously monitors for threats and suspicious activities, enabling you to act swiftly and mitigate risks effectively.
Better yet? The Runtime Sensor integrates seamlessly with your existing systems, providing robust protection without adding complexity. By automating threat detection and streamlining your security operations, Wiz helps you maintain a secure and compliant cloud environment. Request a live demo and see for yourself.
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