¶ OpenBSD
¶ Operating Systems
OpenBSD has a way of surprising people—not through flashy marketing, not through grand claims, and not through promises of transforming the industry overnight, but through a quiet, consistent dedication to craftsmanship. It’s a system that speaks softly and carries a long history of thoughtful engineering. If you spend enough time in the world of operating systems, you eventually encounter OpenBSD, sometimes unexpectedly, as the unsung backbone behind firewalls, routers, VPN appliances, embedded systems, research labs, or critical infrastructure. You soon realize that it’s not a system trying to be everything. Instead, it’s trying to be right.
This course, spanning a hundred articles, aims to explore that world. It’s not just about learning commands or editing configuration files; it’s about understanding the philosophy behind OpenBSD—why it’s designed the way it is, why certain choices are deliberate, and why its developers care so deeply about correctness, clarity, security, and simplicity. This introduction is your first step into that landscape. By the end of the journey, you’ll find that OpenBSD isn’t merely an operating system; it’s a way of thinking about systems as a whole.
To appreciate OpenBSD, it helps to begin with a bit of context. Unix systems have always had their own personalities. Some are built to scale across massive datacenters; others prioritize compatibility or sheer performance. OpenBSD stands apart because it prioritizes something most systems consider “nice to have,” not “foundational”: correctness. That one word drives almost everything in the project. Code is audited relentlessly, not just for security holes but for clarity and sanity. Features aren’t rushed. Decisions aren’t made on the basis of hype. What gets added lasts, and what exists is polished until it feels solid, predictable, and elegant.
That sense of stability is one of the first things people notice when they start using OpenBSD. There are no sudden shifts in design philosophy, no chaotic ecosystem swaps, no tools thrown in just because they're trendy. Even after decades of development, the system still feels coherent, as if every part knows its place. The userland utilities, the kernel, the networking stack, the manual pages, the installer, and the ports system all share a sense of thoughtful consistency. It’s the kind of system that encourages you to slow down, read the documentation, and understand what’s happening rather than rushing to copy-paste commands from somewhere.
Throughout this course, you’ll learn how that consistency took shape. You’ll encounter OpenBSD’s approach to security, not as a bolt-on feature but as something woven into the fabric of the system. The team doesn’t simply patch vulnerabilities; they redesign components so entire classes of bugs become less likely. You’ll see how privilege separation, secure-by-default configurations, memory protections, mitigations, cryptographic rigor, and careful code review play into real-world reliability. OpenBSD isn’t about fear-driven security; it’s about engineering systems that behave predictably and resist entire categories of mistakes.
That mindset affects every aspect of the system, including its famous documentation. OpenBSD’s manual pages are often praised as some of the clearest and most practical in the Unix world. They don’t hide details behind abstractions or assume a particular background. They explain exactly what a tool does, how it behaves, and why certain defaults exist. As you explore the system, you’ll see that reading manual pages becomes part of the natural rhythm of using OpenBSD. Instead of frustration, you experience understanding. Instead of losing hours to trial and error, you find answers waiting in plain language.
The simplicity and clarity of OpenBSD isn’t accidental. It comes from a culture that believes users deserve to understand their systems. The installer reflects that philosophy. The base system reflects that philosophy. The networking stack, the firewall PF, the cryptographic libraries, the init system—all of it is designed so you can grasp the whole without feeling like the system is resisting your curiosity. Even complex tools feel approachable when they're designed with consistency.
One of the most defining features you’ll explore in this course is PF, the packet filter. If you’ve ever struggled with complex firewall rules, scattered configurations, or unclear packet flows, PF might feel like a breath of fresh air. It reads like a policy language rather than a pile of commands. It feels almost like English—a concise, precise way to describe what you want your network to do. When people encounter PF for the first time, they often get a sense that networking doesn’t have to be cryptic. It can be clear, readable, and elegant. PF is a perfect example of OpenBSD’s design philosophy woven into a practical tool.
You’ll also explore OpenBSD’s networking stack, which is renowned for its cleanliness and correctness. Many projects—even large ones—borrow ideas, patterns, and even code from OpenBSD’s implementation because of its quality. When you trace packets through the system, you get a sense of how carefully the design is laid out. The predictable behavior becomes especially valuable when you're troubleshooting, building firewalls, managing routing tables, configuring VPNs, or setting up secure services.
Another area where OpenBSD shines, and one that this course will dive into deeply, is cryptography. OpenBSD has been a pioneer in secure cryptographic defaults and in designing libraries that are both robust and sane. You’ll learn about OpenSSH—an OpenBSD project that became the standard for secure remote access across the world. You’ll study how LibreSSL emerged as a response to systemic issues in widely used cryptographic libraries. You’ll see how OpenBGPD and OpenNTPD were created with security and simplicity at their core. And you’ll come to appreciate how these tools reflect a commitment not just to building software, but to building software that people can rely on for decades.
Throughout the course, you’ll learn how OpenBSD approaches hardware support. Unlike some operating systems that chase hardware at any cost, OpenBSD focuses on supporting what it can support well. Drivers are written carefully. Choices are made deliberately. There is a preference for hardware that is documented, open, and maintainable. This might mean having a more curated selection of supported devices, but it also means that when something works, it tends to work smoothly, clearly, and consistently. You’ll develop an understanding of why OpenBSD values openness in hardware vendors and how that impacts security, stability, and reliability.
Another theme you’ll encounter is OpenBSD’s base system. Unlike many operating systems that rely heavily on external packages for core functionality, OpenBSD’s base environment is complete, coherent, and self-contained. You don’t need to assemble the operating system yourself. It comes with everything a secure server or workstation needs: networking tools, compilers, shells, daemons, cryptographic utilities, firewalls, documentation, and sensible defaults. The ports and packages system extend the base, but the foundation is solid on its own. This makes OpenBSD feel less like a collection of components and more like a single, unified whole.
Over the course of these articles, you’ll also spend time understanding the OpenBSD release process. Every six months—reliably, predictably, without being rushed—the project makes a release. Each release is more than a version bump; it’s a reflection of ongoing refinement and careful auditing. This schedule gives users a sense of stability that’s rare in the software world. You don’t have to worry about sudden surprises or chaotic breaking changes. Instead, you get thoughtful evolution. As you learn the system, you’ll begin to appreciate how valuable that predictability is.
As you move deeper into OpenBSD, you’ll also discover how much it teaches you about systems as a whole. It’s not just about OpenBSD-specific tools. It’s about understanding good practices, learning how to think about configuration clearly, understanding security as a mindset, and appreciating the elegance of simple designs. Many people who learn OpenBSD find that it makes them better at working with other systems as well. It sharpens your intuition. It encourages you to think about defaults, to read documentation, to reason carefully rather than patch hastily, and to value clarity over cleverness.
Toward the later stages of this course, you’ll explore how OpenBSD fits into modern computing environments. You’ll see how it behaves in virtualized systems, cloud environments, routing appliances, clusters, edge networks, and personal machines. OpenBSD isn’t designed to chase every trend, but its strength lies in its reliability and its discipline. In places where stability matters, in systems that need to be trusted, in networks where unpredictability isn’t an option, OpenBSD shines quietly but unmistakably.
You’ll also explore how OpenBSD fosters a particular kind of user: someone who works slowly, carefully, and deliberately. The community values simplicity, readability, and integrity. Instead of seeking shortcuts or quick hacks, it encourages understanding and craftsmanship. This course will introduce you to that culture—not to idolize it, but to learn from it. OpenBSD’s culture is part of its strength, and understanding that culture helps you use the system more effectively.
By the time you reach the end of the hundred articles, you’ll have a deep, intuitive grasp of OpenBSD. You’ll understand how the system boots, how it configures itself, how it secures itself, how it manages services, how it handles networking, how its tools fit together, and how its design philosophy influences its behavior. You’ll feel confident in deploying it as a server, a firewall, a workstation, a router, or a specialized appliance. And perhaps most importantly, you’ll develop a sense of appreciation for the care that goes into building something as deliberate and consistent as OpenBSD.
This introduction is your invitation into that world. OpenBSD isn’t a system that screams for attention. It doesn’t try to impress you with buzzwords or chase trends. Instead, it offers something quieter but far more rare: correctness, clarity, stability, security, and craftsmanship. If you’re ready to explore a system built with intention, thought, and integrity, then this journey is exactly where you belong.
Let’s begin.
¶ OpenBSD
¶ Beginner Level
1. Introduction to OpenBSD: History and Philosophy
2. Understanding the OpenBSD Security Model
3. System Requirements for Installing OpenBSD
4. Downloading and Preparing OpenBSD Installation Media
5. Step-by-Step OpenBSD Installation Guide
6. Post-Installation Setup and Configuration
7. Navigating the OpenBSD File System Hierarchy
8. Basic Command-Line Tools and Utilities
9. Understanding OpenBSD User and Group Management
10. File Permissions and Ownership in OpenBSD
11. Using the OpenBSD Package Manager (pkg_add)
12. Installing and Removing Software Packages
13. Configuring Network Interfaces in OpenBSD
14. Basic Shell Scripting in OpenBSD
15. Managing Processes and Services
16. Using cron and at for Task Scheduling
17. Introduction to OpenBSD Logging and Monitoring
18. Configuring and Using the OpenBSD Firewall (PF)
19. Basic PF Rules: Allowing and Denying Traffic
20. Setting Up SSH for Secure Remote Access
¶ Intermediate Level
21. Advanced User and Group Management
22. Configuring Disk Partitions and File Systems
23. Using Soft Updates and Journaling in OpenBSD
24. Setting Up RAID with OpenBSD
25. Configuring Network Time Protocol (NTP)
26. Setting Up a DHCP Server in OpenBSD
27. Configuring a DNS Server with Unbound
28. Setting Up a Web Server with httpd
29. Configuring Email Services with OpenSMTPD
30. Setting Up a File Server with NFS
31. Configuring Samba for Windows File Sharing
32. Using OpenBSD as a Router
33. Configuring VLANs and Network Bridging
34. Setting Up a VPN with OpenIKED
35. Configuring PF for NAT and Port Forwarding
36. Using PF for Load Balancing and Redundancy
37. Setting Up a Secure FTP Server
38. Configuring and Using OpenBSD's Packet Filter (PF) Logs
39. Monitoring System Performance with systat and top
40. Backing Up and Restoring Data in OpenBSD
¶ Advanced Level
41. Deep Dive into OpenBSD Kernel Configuration
42. Compiling and Installing a Custom Kernel
43. Using OpenBSD's Security Features: W^X, ASLR, and More
44. Configuring chroot and jail Environments
45. Setting Up and Managing Virtual Machines with vmm
46. Using OpenBSD as a Hypervisor
47. Configuring Encrypted Disk Partitions
48. Implementing Full Disk Encryption with softraid
49. Setting Up a Secure Gateway with OpenBSD
50. Configuring High Availability with CARP and pfsync
51. Advanced PF Configuration: Anchors and Tables
52. Using PF for Traffic Shaping and QoS
53. Configuring OpenBSD for Wireless Networks
54. Setting Up a Captive Portal with PF
55. Implementing Intrusion Detection with snort
56. Using OpenBSD for Penetration Testing
57. Configuring OpenBSD for Forensic Analysis
58. Setting Up a Secure Web Proxy with relayd
59. Using OpenBSD for Network Monitoring
60. Configuring OpenBSD for VoIP Services
¶ Expert Level
61. Writing and Contributing to OpenBSD Code
62. Understanding and Using OpenBSD's ProPolice and SSP
63. Configuring OpenBSD for High-Performance Computing
64. Using OpenBSD in Embedded Systems
65. Setting Up OpenBSD for Cloud Environments
66. Configuring OpenBSD for IoT Devices
67. Implementing OpenBSD in Military and Defense Systems
68. Using OpenBSD for Space and Satellite Networks
69. Configuring OpenBSD for Quantum Computing
70. Advanced Network Security with OpenBSD
71. Implementing Zero-Trust Architecture with OpenBSD
72. Configuring OpenBSD for Multi-Tenant Environments
73. Using OpenBSD with Blockchain Nodes
74. Setting Up OpenBSD for AI and Machine Learning
75. Configuring OpenBSD for Big Data and Analytics
76. Using OpenBSD for Real-Time Applications
77. Implementing OpenBSD in Financial Systems
78. Configuring OpenBSD for Healthcare Applications
79. Using OpenBSD in Industrial Control Systems
80. Setting Up OpenBSD for Telecommunications
¶ Specialized Topics
81. OpenBSD for Small Businesses: Best Practices
82. OpenBSD for Home Labs: A Practical Guide
83. OpenBSD for Educational Institutions
84. OpenBSD for Research and Development
85. OpenBSD for Gaming Servers: Low Latency and Performance
86. OpenBSD for Media and Entertainment Workloads
87. OpenBSD for Healthcare and Medical Applications
88. OpenBSD for Financial Services and Trading
89. OpenBSD for Retail and E-Commerce
90. OpenBSD for Manufacturing and Industrial Automation
91. OpenBSD for Telecommunications
92. OpenBSD for Government and Public Sector
93. OpenBSD for Non-Profit Organizations
94. OpenBSD for Startups and SMBs
95. OpenBSD for Cloud Service Providers
96. OpenBSD for Managed Service Providers (MSPs)
97. OpenBSD for DevOps and CI/CD Pipelines
98. OpenBSD for Disaster Recovery as a Service (DRaaS)
99. OpenBSD for Backup as a Service (BaaS)
100. The Future of OpenBSD: Trends and Innovations