OpenBSD as a server operating system: The Unix derivative prized for security and stability

In the realm of server operating systems, OpenBSD is in a class of its own, known for its security focus and system integrity. With roots in the legendary Berkeley Software Distribution, it combines traditional Unix principles with modern security concepts. The following article explains what makes OpenBSD a trusted and efficient server operating system.

What sets OpenBSD apart?

OpenBSD is a free, open-source operating system based on the principles of security, portability and standards compliance. It belongs to the family of UNIX-like operating systems and is a derivative of the Berkeley Software Distribution (BSD), a version of UNIX originally developed at the University of California, Berkeley. It was forked from NetBSD by Theo de Raadt in 1995 and is available under the BSD licence, which allows users and developers to use, modify and redistribute the code without having to comply with strict licensing constraints.

OpenBSD is particularly known for its proactive approach to security. The operating system includes numerous built-in security features, including strict memory protection mechanisms, various cryptographic functions and a default minimal installation that reduces the potential attack surface.

The source code of OpenBSD is regularly subjected to a rigorous review to minimise bugs and security vulnerabilities. This code-review process contributes significantly to the system's reliability and security. It also includes a range of versatile networking features, making it a popular choice for use in security-critical environments as a network server or firewall.

Which technical aspects do OpenBSD servers excel in?

OpenBSD servers are characterised by their excellent security, minimalist approach, robust network-security features, strong cryptography, high code quality and broad portability, making them an ideal choice for secure and stable server environments.

• Enhanced security

OpenBSD is known for its comprehensive security features. It uses proactive security techniques such as Address Space Layout Randomization (ASLR), strict memory-access controls and a high degree of code review to minimise vulnerabilities. These characteristics make OpenBSD one of the most secure operating systems, ideal for servers that handle sensitive data.

• Minimalism and simplicity

OpenBSD follows a minimalist approach, where only the essential components are installed by default. This reduces the attack surface and improves clarity and maintainability of the system.

• Network security

OpenBSD includes the packet filter pf (packet filter), a powerful and flexible firewall service that supports routing, NAT, traffic shaping and more. This makes OpenBSD an excellent choice for deployment as a firewall or router.

• Cryptographic strength

The system places a strong emphasis on robust cryptography, including secure random-number generation and the integration of modern cryptographic algorithms, which is essential for server applications that require secure data transmission.

• High-quality code

OpenBSD has a strict code review process and places great emphasis on correctness and code quality. This results in a very stable and reliable operating system, which is crucial for running servers.

• Portability

OpenBSD supports a wide range of hardware platforms and architectures, making it highly versatile.

• Standards compliance

OpenBSD adheres closely to various system standards, ensuring compatibility with other systems and applications and simplifying integration into existing environments.

These technical aspects make OpenBSD a solid choice for servers in many areas, particularly where security and stability are paramount.

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OpenBSD versions and lifecycle

OpenBSD follows a regular release cycle and has a specific policy for the support of its versions. Regular updates support OpenBSD’s philosophy of providing up-to-date software that includes the latest security features and improvements.

Semi-annual release cycle: OpenBSD has a tradition of releasing two versions per year. These releases typically occur in April/May and October/November. Each release is identified by a version number that increases incrementally (e.g. 6.8, 6.9, 7.0, etc.).

Lifecycle of a version: Each OpenBSD version typically receives one year of support. During this time bug fixes and security updates are provided. After this year, support is discontinued and users are encouraged to upgrade to a newer version.

No long-term support (LTS): Unlike some other operating systems, OpenBSD does not offer long-term support (LTS) for specific versions. The developers focus on regularly releasing new versions that include both improvements and security updates.

What weaknesses does OpenBSD have as a server operating system?

Despite its many strengths, particularly in security, there are some aspects that can be considered weaknesses of OpenBSD as a server operating system:

• Focus on security over user-friendliness: OpenBSD's strong focus on security can come at the expense of user-friendliness and convenience. Some security features may be perceived as restrictive and require additional configuration work.
• Complexity in setup and maintenance: OpenBSD can be challenging for new users or those less familiar with UNIX-like systems. Configuring and maintaining the system often requires deep technical knowledge.
• Updates and upgrades: OpenBSD's regular releases may necessitate frequent updates and upgrades, which can be a challenge for some administrators, particularly in environments that prioritise stability and long-term support.
• Hardware support: OpenBSD has more limited hardware support compared with other operating systems such as Linux or Windows. This can restrict the choice of compatible hardware, especially with newer or specialised devices.
• Performance: In some cases OpenBSD may lag behind other operating systems in terms of performance, particularly where optimised drivers or specific software performance tweaks play a role.
• Software availability: While OpenBSD offers a considerable number of packages and ports, the available software selection may not be as extensive as on other operating systems. Some modern applications or specialised software solutions may be missing or not up to date.
• No commercial support: Unlike operating systems such as Red Hat Enterprise Linux or Windows Server, OpenBSD does not have broad commercial support. This can be a disadvantage for businesses that rely on comprehensive support.

These factors should be considered when deciding whether to deploy OpenBSD as a server operating system, particularly with regard to specific requirements and use cases.

Tip: Also see BSD operating systems compared: FreeBSD vs OpenBSD vs NetBSD for the differences between the various BSD variants.

OpenBSD compared with other server operating systems

When choosing the appropriate server operating system, attention should be paid to the differences and individual characteristics of the respective alternatives:

OpenBSD vs Linux

Linux and OpenBSD are both powerful and versatile operating systems, but they differ in key aspects: Linux offers broader hardware support and a wider selection of software, making it a more versatile choice for a variety of applications. OpenBSD, by contrast, places a stronger emphasis on security and code quality, with rigorous security features and a minimalist approach that make it a preferred choice for security‑critical environments. While Linux is known for its user‑friendly distributions and large community, OpenBSD is distinguished by its consistent commitment to security, simplicity and correct code.

For more information on the differences between individual Linux distributions, see the article:

Best Linux for servers: Which distributions are suitable?

OpenBSD vs Windows

OpenBSD and Windows differ fundamentally in their philosophy and target audience: OpenBSD is a free, security‑focused Unix‑like operating system known for its security features, minimalist design approach and open‑source nature, and is favoured by experienced system administrators and used in security‑critical environments. Windows, a commercial product from Microsoft, offers broader hardware and software compatibility, ease of use and extensive commercial support, making it a popular choice for business environments and home users. While OpenBSD is valued for its strict security orientation and stability, Windows is characterised by its graphical user interface, extensive application compatibility and strong presence in the desktop and enterprise markets.

Overall, the choice of server operating system depends heavily on the specific requirements and the context.

When should an OpenBSD server be preferred?

OpenBSD is ideal for systems where security is a decisive criterion, such as firewalls, VPNs, or other network infrastructures that require a high level of security.

Due to its powerful and flexible packet filter 'pf', OpenBSD is an excellent choice for implementing specialised network services such as firewalls, routers or intrusion detection systems.

OpenBSD places a strong emphasis on robust cryptography, making it ideal for applications that require secure data transmission or storage.

OpenBSD is also commonly used in academic educational centres or research environments, where its open-source character and the possibility for in-depth examination and customisation of the operating system are appreciated.

Our article is based on our own experience and research as well as information from external sources.

References & further links on the topic:

https://www.openbsd.org/ (Official website of the OpenBSD Project)