CentOS Linux 6

Basic information

• Model: CentOS Linux 6
• Version: 6.x (derived from Red Hat Enterprise Linux 6)
• Release Date: July 10, 2011
• Minimum Requirements:
  • Command Line Interface (CLI): 392MB RAM, 1GB disk space
  • Graphical User Interface (GUI): 512MB RAM, 5GB disk space
  • General Recommended: 1 GHz processor, 1 GB RAM, 10 GB disk space
• Supported Operative Systems: CentOS 6 itself is an operating system. It supports x86 and x86-64 architectures.
• Latest Stable Version: CentOS 6.10
• End of Support Date: November 30, 2020 (Full update EOL was May 10, 2017)
• End of Life Date: November 30, 2020
• Auto-update Expiration Date: Auto-updates ceased with the End of Life on November 30, 2020, as it no longer receives official updates.
• License Type: Open Source
• Deployment Model: Primarily designed for server environments, but configurable for desktop use.

Analysis: CentOS Linux 6, released in 2011, provided a stable, open-source alternative to Red Hat Enterprise Linux. Its long lifecycle was a key feature, offering 10 years of support through regular updates. However, it reached its official End of Life on November 30, 2020, meaning it no longer receives security updates or bug fixes, posing significant risks for continued use. Minimum requirements are modest, reflecting its age, but recommended specifications are higher for practical use.

Technical Requirements

• RAM: Minimum 392MB for CLI, 512MB for GUI. Recommended 1GB for basic tasks, 4GB or more for multitasking and server workloads. The 64-bit version supports up to 3TB of RAM.
• Processor: Minimum 1 GHz processor. A 2 GHz dual-core processor or higher is recommended for better performance. It supports x86 and x86-64 architectures.
• Storage: Minimum 1GB for CLI, 5GB for GUI. Recommended 10GB for basic installations, with 20GB or more for multiple applications and server loads.
• Display: Supports standard display configurations for graphical environments like GNOME 2.28 and KDE 4.3.4.
• Ports: Standard network ports for connectivity and various USB ports are supported.
• Operating System: CentOS Linux 6 is the operating system itself.

Analysis: The technical requirements for CentOS 6 are relatively low by modern standards, making it suitable for older hardware or resource-constrained virtual environments. However, for optimal performance and to run contemporary applications, exceeding the minimums, especially for RAM and storage, is advisable. Its support for both 32-bit (x86) and 64-bit (x86-64) architectures provided broad hardware compatibility during its active lifecycle.

Support & Compatibility

• Latest Version: CentOS 6.10
• OS Support: CentOS 6 is an operating system that supports x86 and x86-64 processor architectures.
• End of Support Date: November 30, 2020.
• Localization: As a derivative of Red Hat Enterprise Linux, CentOS 6 supports multiple languages, though specific details on localization packages are not extensively documented in general overviews.
• Available Drivers: CentOS 6 generally offers good hardware compatibility. However, for newer or specialized hardware, obtaining compatible drivers may require using third-party repositories or manual compilation, especially after its EOL.

Analysis: CentOS 6 is no longer officially supported, meaning it does not receive security updates, bug fixes, or new features from the CentOS Project. This significantly impacts its compatibility with modern software and hardware. While third-party solutions like CloudLinux 6 offered extended support until June 30, 2024, for specific components like OpenSSL, this is not a comprehensive solution for the entire OS. Users face challenges with outdated software packages and limited application compatibility. Migration to a newer, supported operating system is strongly recommended.

Security Status

• Security Features: CentOS 6 includes built-in security features such as SELinux (Security-Enhanced Linux) for mandatory access control, iptables for firewall management, and auditing capabilities. It supports SSH hardening through key-based authentication, disabling root logins, and changing default SSH ports. Fail2Ban can be implemented to protect against brute-force attacks.
• Known Vulnerabilities: Numerous Common Vulnerabilities and Exposures (CVEs) exist for CentOS 6, particularly after its End of Life. These include kernel vulnerabilities and issues in components like OpenSSL (e.g., CVE-2020-1971). Without official updates, these vulnerabilities remain unpatched.
• Blacklist Status: There is no general "blacklist" status for the CentOS 6 operating system itself. However, individual servers running unpatched CentOS 6 may be vulnerable to exploits, leading to their IP addresses being blacklisted by security services if compromised.
• Certifications: CentOS, as a community-driven project, typically does not pursue formal security certifications like its upstream, Red Hat Enterprise Linux.
• Encryption Support: CentOS 6 supports various encryption methods, including full disk encryption using LUKS (Linux Unified Key Setup) for block devices, file system encryption with eCryptfs, and encrypted containers via tools like VeraCrypt or BestCrypt.
• Authentication Methods: Supports standard username and password authentication, Pluggable Authentication Modules (PAM), and integration with directory services like LDAP and Kerberos. Two-factor authentication (2FA) can be implemented for services like SSH using Google Authenticator (TOTP), Yubikey, or FreeOTP.
• General Recommendations: Due to its EOL status, the primary recommendation is to migrate to a currently supported operating system. For systems that cannot be immediately migrated, implementing all available security features, disabling unnecessary services, hardening SSH, utilizing firewalls, and employing intrusion detection systems are critical. Extended support from third-party vendors (like CloudLinux) can provide some security patches for specific components.

Analysis: The security posture of CentOS 6 is severely compromised due to its End of Life status. While it incorporated robust security features during its supported lifecycle, the absence of ongoing official security updates leaves systems exposed to known and newly discovered vulnerabilities. Running CentOS 6 in production environments without a comprehensive extended support plan or immediate migration strategy constitutes a major security risk. Proactive security measures and layered defenses are essential but cannot fully mitigate the risks of an unsupported OS.

Performance & Benchmarks

• Benchmark Scores: Comparisons with CentOS 7 indicate that CentOS 6 generally performs slower in CPU processing speed (CentOS 7 was approximately 15% faster) and random write/file delete operations. However, CentOS 6 showed comparable or sometimes better performance in certain disk I/O and network throughput tests depending on the specific workload.
• Real-World Performance Metrics: During its active life, CentOS 6 was noted for being fast, stable, and modern, with a small memory footprint and snappy response times. Application launch speeds were described as almost instantaneous.
• Power Consumption: As a server-oriented operating system, CentOS 6 is generally efficient, but specific power consumption metrics are highly dependent on the underlying hardware and workload. No generic OS-level benchmarks for power consumption are readily available.
• Carbon Footprint: The carbon footprint of an operating system is not directly quantifiable. It is primarily influenced by the energy consumption of the hardware it runs on and the efficiency of the data centers.
• Comparison with Similar Assets: CentOS 6 is binary-compatible with Red Hat Enterprise Linux 6 (RHEL 6), offering similar performance characteristics without the licensing cost. Compared to newer distributions like CentOS 7, it generally exhibits lower performance in CPU-intensive tasks due to an older kernel and less optimized resource management. It was praised for its stability and long lifecycle compared to more frequently updated distributions.

Analysis: CentOS 6 delivered solid performance and stability during its supported period, particularly for server workloads where reliability was prioritized over cutting-edge features. While newer versions like CentOS 7 offer performance improvements in many areas, CentOS 6 was considered efficient for its time. Its performance characteristics were well-suited for enterprise environments seeking a dependable and predictable platform. However, its age means it does not leverage modern hardware optimizations as effectively as contemporary operating systems.

User Reviews & Feedback

User reviews and feedback for CentOS 6, particularly during its active support phase, consistently highlighted its strengths in stability and reliability. Users valued its enterprise-level performance without the associated licensing fees of Red Hat Enterprise Linux. Its compatibility with RHEL made it a preferred choice for production environments, web hosting, cloud hosting, and critical applications where uptime and consistency were paramount. The strong community support was also frequently cited as a significant advantage, aiding in troubleshooting and general administration.

Weaknesses often mentioned included the use of older software versions compared to more rapidly evolving distributions, which could lead to a "clunky" feel for desktop users. Some users experienced compatibility issues with certain applications or found the update frequency to be slow. The most significant weakness, however, became its End of Life status, which created uncertainty and forced users to migrate or seek costly extended support. Installation could sometimes present minor challenges, such as manual DHCP setup.

Recommended use cases for CentOS 6 were predominantly server-side, including web servers, database servers, and virtualization hosts, where its rock-solid stability and predictable environment were highly beneficial.

Summary

Red Hat CentOS Linux 6 was a highly regarded open-source operating system, released on July 10, 2011, and derived from Red Hat Enterprise Linux 6. It was celebrated for its exceptional stability, reliability, and long lifecycle, making it a popular choice for enterprise server environments, web hosting, and critical applications. Its modest technical requirements allowed it to run efficiently on a range of hardware, while its robust security features, including SELinux and strong authentication options, provided a secure foundation during its supported period.

However, the asset reached its official End of Life (EOL) on November 30, 2020, meaning it no longer receives security updates, bug fixes, or new features from the CentOS Project. This EOL status is its most critical weakness, exposing systems to numerous known and unpatched vulnerabilities. While third-party extended support options existed for a limited time, they do not cover the entire operating system. Performance, while solid for its era, is generally surpassed by newer operating systems like CentOS 7, which offer better optimizations for modern hardware.

In summary, CentOS Linux 6 was a highly effective and reliable operating system for its time, particularly for server deployments. Its strengths lay in its stability, RHEL compatibility, and community support. However, its current unsupported status renders it unsuitable for production environments due to severe security risks. The explicit recommendation is to migrate to a currently supported operating system to ensure security, compatibility, and access to ongoing updates.

The information provided is based on publicly available data and may vary depending on specific device configurations. For up-to-date information, please consult official manufacturer resources.