OpenBSD

Overview

OpenBSD is a free and open-source, security-focused, Unix-like operating system based on the Berkeley Software Distribution (BSD). It is known for its emphasis on code correctness, proactive security, and integrated cryptography. OpenBSD is developed by a worldwide community of volunteers and is led by Theo de Raadt from Calgary, Alberta, Canada.

History

OpenBSD originated in 1995 as a fork of NetBSD 1.0. Theo de Raadt, one of the founders of NetBSD, started the project due to disagreements with the NetBSD core team. The first official release of OpenBSD was version 2.0, released in October 1996. Since then, OpenBSD has maintained a bi-annual release cycle, with each release focusing on security enhancements, code audits, and new features.

Design Philosophy

OpenBSD's design philosophy is centered on security, simplicity, and code correctness. The project emphasizes thorough code audits, proactive security measures, and the principle of least privilege. OpenBSD developers prioritize writing clean, readable, and maintainable code, which contributes to the system's overall stability and security.

Security Features

OpenBSD is renowned for its security features, many of which have been adopted by other operating systems. Some key security features include:

• **Proactive Security**: OpenBSD developers regularly audit the codebase to identify and fix security vulnerabilities before they can be exploited.
• **W^X (Write XOR Execute)**: This security policy ensures that memory can either be writable or executable, but not both, preventing certain types of attacks.
• **Address Space Layout Randomization (ASLR)**: ASLR randomizes the memory addresses used by system and application processes, making it more difficult for attackers to predict the location of specific functions or data.
• **Privilege Separation**: This technique divides programs into smaller parts, each running with the minimum necessary privileges, reducing the impact of potential security breaches.
• **Pledge and Unveil**: These system calls allow applications to restrict their own capabilities and file system access, further limiting the potential damage from security vulnerabilities.

Cryptography

OpenBSD has a strong focus on integrated cryptography. The system includes various cryptographic tools and libraries, such as:

• **OpenSSH**: A widely-used implementation of the Secure Shell (SSH) protocol, developed as part of the OpenBSD project.
• **LibreSSL**: A fork of the OpenSSL cryptographic library, created to improve code quality and security.
• **IPsec**: A suite of protocols for securing Internet Protocol (IP) communications through encryption and authentication.

Networking

OpenBSD includes a robust networking stack, with support for various protocols and features. Some notable networking components include:

• **PF (Packet Filter)**: A powerful and flexible firewall developed for OpenBSD, used for network address translation (NAT), traffic shaping, and packet filtering.
• **CARP (Common Address Redundancy Protocol)**: A protocol that allows multiple hosts to share the same IP address, providing high availability and failover capabilities.
• **IKEv2 (Internet Key Exchange version 2)**: A protocol used to set up secure, authenticated communications channels, commonly used in virtual private networks (VPNs).

Development Process

OpenBSD's development process is highly collaborative, with contributions from developers around the world. The project uses a centralized source code repository, and changes are reviewed and tested extensively before being integrated. OpenBSD's bi-annual release cycle ensures that new features and security improvements are regularly made available to users.

Licensing

OpenBSD is released under the ISC license, a permissive open-source license similar to the MIT license. This licensing model allows for broad use and redistribution of the software, while ensuring that the original authors receive credit for their work.

Hardware Support

OpenBSD supports a wide range of hardware platforms, including:

• **amd64**: The 64-bit x86 architecture, commonly used in modern desktop and server systems.
• **i386**: The 32-bit x86 architecture, supported for legacy systems.
• **arm64**: The 64-bit ARM architecture, used in many embedded and mobile devices.
• **sparc64**: The 64-bit SPARC architecture, used in some high-end servers.

Community and Documentation

The OpenBSD community is known for its dedication to high-quality documentation. The project provides comprehensive man pages, a detailed FAQ, and various other resources to help users and developers. The community also organizes events such as the bi-annual Hackathons, where developers gather to collaborate on the project.

See Also

• NetBSD
• FreeBSD
• OpenSSH
• LibreSSL
• Packet Filter
• Address Space Layout Randomization

OpenBSD logo featuring a pufferfish mascot.

References

• Official OpenBSD website
• OpenBSD man pages