Strengthening Linux Server Security: OpenSCAP, Lynis, AIDE, SELinux, Fail2ban, Firewalld, and FIPS Mode

Strengthening Linux Server Security: OpenSCAP, Lynis, AIDE, SELinux, Fail2ban, Firewalld, and FIPS Mode

Securing your Linux server is crucial given the increasing number of cyber attacks against Linux systems. Linux offers many benefits as a stable and flexible server operating system, making it an ideal platform for hosting vital apps and sensitive information. To fortify your Linux server, we’ll discuss several open source tools and methods that can help you reinforce your defenses against potential threats. We recommend employing OpenSCAP, Lynis, AIDE, SELinux, Fail2ban, Firewalld, and enabling FIPS mode to optimize your system’s resistance to intrusions.

OpenSCAP: Assessing and Auditing Server Security

OpenSCAP is a free and open-source solution designed to evaluate the security posture of Linux servers based on SCAP (Security Content Automation Protocol) guidelines created by NIST (National Institute of Standards and Technology). By utilizing OpenSCAP, you can perform thorough vulnerability assessments and ensure your system meets essential security requirements. For a step-by-step introduction to deploying and working with OpenSCAP, refer to their official documentation at .

Lynis: In-depth Security Auditing

To further enhance your Linux server's security, consider leveraging Lynis - an open-source utility offering advanced security auditing functions. This application performs comprehensive examinations, helping you discover potential weaknesses or noncompliant configurations. While slightly more sophisticated compared to OpenSCAP, Lynis provides a deeper evaluation, serving as a critical component in your security arsenal. Visit the official Lynis website at for a more in-depth explanation of the software and how to operate it effectively.

AIDE: Detecting Unauthorized File Changes

AIDE (Advanced Intrusion Detection Environment) is an open-source file integrity checking program designed to safeguard important system documents from unapproved alterations. The software works by comparing the actual state of these files to a previously defined reference point, alerting users if discrepancies are discovered. Quick detection of file modifications enables AIDE to help pinpoint malware attacks or intrusions, enabling rapid response measures. To delve into the details of AIDE and its usage, explore the project's official site at .

SELinux: Enforcing Mandatory Access Control

SELinux (Security-Enhanced Linux) is an integrated security mechanism implemented within the Linux kernel itself. Utilizing MAC (Mandatory Access Control) rules, it assigns prescribed roles and privileges to running processes, augmenting conventional user space protection methods. Optimally configured and employed, SELinux greatly fortifies your server's defenses against numerous types of security hazards. For an in-depth understanding of SELinux and its setup process, head over to the official SELinux website at

Fail2ban: Protecting Against Brute Force Attacks

Fail2Ban is a popular open-source solution that automatically blocks IP addresses following multiple failed login endeavors, thereby reducing the likelihood of successful brute-force assaults on network services such as SSH or web applications. By implementing this elementary but effective safety measure, Fail2Ban reinforces the server's overall security posture. For further insight into Fail2Ban and its installation procedures, visit the official Fail2Ban website at

Firewalld: Controlling Network Traffic

Firewalld is the standard firewall on many Linux systems, including those based on AlmaLinux. This software empowers administrators to regulate inbound and outbound network communication by creating precise rules and settings. Such fine-grained management improves the server's resistance to unwanted incursions and cyberattacks. With proper configuration using a "deny all" rule set and allowing necessary TCP and UDP ports, firewalld fortifies your server even further. This ensures that only authenticated traffic is permitted through the firewall, whether entering or exiting the system. Discover the ins and outs of firewalld and its customization options by visiting the official firewalld website at

FIPS Mode: Meeting Stringent Security Standards

Enabling FIPS mode on your Linux machine may enhance its overall security stance. FIPS mode necessitates strict adherence to stringent security conditions and confirms conformance with exact cryptography norms. Consequently, your server gains increased immunity against particular categories of attacks that capitalize on feeble cryptographic techniques. If you want to know more about FIPS mode and its benefits, consult the FIPS 140-3 Wikipedia page:

The International Organization for Standardization (ISO) has issued numerous standards relevant to information security, which include:

1. ISO/IEC 27001: Specifies guidelines for developing, implementing, and managing an Information Security Management System (ISMS).

2. ISO/IEC 27002: Offers recommendations for implementing controls aimed at mitigating identified risks to organizational assets.

3. ISO/IEC 15408 (Common Criteria): Establishes evaluation criteria and assignment of product assurance levels for IT products.

4. ISO/IEC 27034: Provides guidelines for securing web and mobile applications throughout their life cycle.

Apart from these ISO standards, some popular technical specifications and frameworks include:

1. SCAP (Security Content Automation Protocol): Defines standards for automated vulnerability management, compliance checks, and security measurements.

2. SSH (Secure Shell): Ensures safe administrative access and file transfers across network infrastructure using public key authentication and encryption.

3. IPsec (Internet Protocol Security): Protects communication through IP networks via confidentiality, integrity, and authentication.

4. TLS (Transport Layer Security): Provides end-to-end encryption and authentication between clients and servers.

5. SELinux: Implements Mandatory Access Control (MAC) policies, enhancing system security by restricting user privileges.

6. FIPS (Federal Information Processing Standards): Set forth non-mandatory standards for use by US federal agencies and contractors when processing sensitive or classified information.

This compilation is not comprehensive; there exist additional standards, best practices, and technologies integral to cybersecurity within the broader scope of IT.


Securing a Linux server requires a comprehensive and proactive approach. By employing tools like OpenSCAP, Lynis, AIDE, SELinux, Fail2ban, Firewalld, and implementing security best practices, you can establish a formidable defense for your server. Regular assessments, robust access controls, vigilant monitoring, and keeping your server up-to-date are equally crucial. By taking these measures, you can safeguard your server, its applications, and data from potential threats and ensure a secure and reliable computing environment. Invest in the security of your Linux server today to protect your critical assets tomorrow.

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Idea is translate using Google Translate, rewrite by Google Bard, Wording for blog post by ChatGPT and addon content by

I want to use this tools for my Linux Security Hardening for Almalinux, can you write a howto for this?



firewalld with deny all policy , limited allow tcp adn udp ports - both ingress and egress traffic.

fips-mode-setup to enable FIPS

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