Learn OpenBSD - Prerequisites Skills & Environment Setup
Preparing the skills and lab environment before installing OpenBSD: basic Unix CLI administration, user and group concepts, TCP/IP networking, the least privilege security mindset, and the hardware, software, and installer image needed to get started.
#Introduction
Welcome to the Learn OpenBSD series! This series will take you through mastering OpenBSD — the open source UNIX-like operating system best known for its security — from installation and day-to-day administration all the way to security-first production. There are 23 sequential episodes in total, so reading each episode in order will build your mastery layer by layer.
OpenBSD is not just "Linux with a pufferfish logo". It is an independent system, forked from NetBSD, with a secure by default philosophy and complete built-in tooling: pf firewall, OpenSSH, LibreSSL, tmux, and OpenSMTPD. Before touching the installer, you need to prepare two things: basic skills and a lab environment. Episode 0 is your map and compass before you set sail.
#Basic Skills You Must Have
| Skill | Why It Matters for OpenBSD |
|---|---|
| Unix CLI | Almost all OpenBSD administration is done from the terminal |
| User & group concepts | Access rights and process isolation start with the user model |
| Networking (IP, routing, ports) | OpenBSD network configuration is purely file- and text-command based |
| Security mindset | OpenBSD is designed on the assumption that the adversary is already inside |
| Experience with other Linux/BSD | Helps, but not required — CLI and networking basics are enough |
Don't worry if some of this still feels abstract; everything will be practiced in the following episodes. The key in this episode is making sure you're comfortable with the CLI and networking, since both are used in almost every episode.
#Unix CLI
You don't need to be a shell expert to start. Just master: directory navigation with cd, reading files with less, checking system information with uname and sysctl, and understanding the pipe | and redirection > concepts. OpenBSD defaults to the ksh shell, and almost all the material in this series uses those basic commands.
#User, Group & Permission
OpenBSD implements the classic UNIX permission model: every file has an owner and a group, plus three permission levels (read, write, execute). In episode 5 you'll learn how to manage users and groups, and more importantly how to use doas for privileged access. For now, understand that minimal access rights are the OpenBSD culture — the concept of least privilege will keep appearing throughout this series.
#Basic Networking
OpenBSD is a networking machine. IP configuration, subnet masks, gateways, DNS, and ports and services are the everyday language of this system. You need to understand at least: what an IP address and subnet are, how the default route works, what a port is, and how TCP/IP is used by services like SSH and HTTP. Episode 8 will cover this in depth.
#Security Mindset
What most sets OpenBSD apart is its point of view: secure by default. Every new feature is first questioned from a security perspective before it is accepted. You will learn to think the same way: disable unnecessary services, grant the least privileges possible, and be suspicious of external input. These are the principles that animate this entire series.
#The Habit of Reading Manuals
One skill that will save you time many times over is reading the man pages. OpenBSD is famous for its outstanding documentation; almost every question you have is already answered there. Build this habit from the first episode: unsure about a command? Open its manual. Checking configuration syntax? Read the man page. This small habit is what separates an operator from a true administrator.
#Software and Hardware to Prepare
| Requirement | Recommendation |
|---|---|
| Virtualization | VirtualBox (free) or Proxmox; pay attention to virtio configuration |
| Physical hardware | x86_64 or arm64 machine with 1 GB RAM or more |
| Installer image | install74.iso or miniroot74.img from openbsd.org |
| Boot media | ISO for a VM, USB drive for physical hardware |
For a basic server, 1 GB RAM is the suggested minimum. OpenBSD is indeed resource-frugal, but you still need room for the base system and the services you run. If you're using a VM, allocate 2 GB for a more comfortable experience.
#Choosing a Version and Architecture
Before downloading an image, settle two choices: the version and the architecture.
| Aspect | Choice | Notes |
|---|---|---|
| Version | Stable release (e.g. 7.4) | The primary choice for learning |
| Architecture | amd64 | Most common and widely supported |
| Platform | VM or physical hardware | VM for flexibility, physical for real practice |
For this series, you'll start from the stable amd64 release — for example install74.iso. The concepts of release, snapshot, and -current will only be covered in episode 20, so don't rush to use non-stable versions now.
#Setting Up a Virtual Lab
#Choosing a Virtualization Platform
VirtualBox is the easiest choice to get started because it's free and cross-platform. Proxmox is better suited for a more serious lab with many VMs. Both support OpenBSD; what matters is configuring virtio for disks and networking to get optimal performance.
#Setting Up the VM
Info
When creating the VM, choose the "OpenBSD" OS type (if available) or "BSD". Recommended settings: 1-2 vCPUs, 2 GB RAM, and an 8-20 GB virtual disk. The network mode can be NAT during installation, then switch to bridge or host-only once the system is running.
Creating the VM is fairly simple: create a new VM, attach the installer image, then boot. Before that, download and verify the installer image first:
ftp https://cdn.openbsd.org/pub/OpenBSD/7.4/amd64/install74.iso
sha256sum install74.isoThe OpenBSD installer presents clear, sequential instructions. The process will be covered in detail in episode 3. For now, make sure your VM can boot from the ISO and reach the installer's welcome screen.
#Hardware Specs for Production
If someday you run OpenBSD on real hardware, remember that this system is famous for being resource-efficient. OpenBSD routers and firewalls can run on machines with little RAM. For a public web server, 1-2 GB RAM is already a reasonable starting point, and storage doesn't need to be large — the full base system is only about 400 MB before adding packages.
#Lab Scenario Throughout the Series
Throughout this series we'll use a single OpenBSD machine as a "lab server" whose role keeps growing: firewall and router, web server, mail server, and even a virtualization host. Consistency helps a lot. Decide from now:
- Hostname: for example
obsd1, short and clear. - Static IP: for example
192.168.10.1/24for one interface as the lab gateway. - Functionality: start as a single VM, then add a second VM when you reach the pf, relayd, and vmm material.
#Closing
In episode 0 you've laid the foundation for the whole series: basic CLI, user/group, networking, and security mindset skills; the software and hardware specs for your lab; and a consistent lab scenario you'll reuse again and again.
Key takeaways:
- OpenBSD demands a basic understanding of Unix and networking, not memorizing a GUI.
- The least privilege security mindset is a culture fused into the system.
- 1 GB RAM is enough to get started; VirtualBox or Proxmox is the best practice ground.
- Prepare the installer image and make sure your VM can boot before episode 3.
In the next episode, episode 1, we'll discuss the history, background, and security philosophy of OpenBSD — from the NetBSD fork in 1995 by Theo de Raadt, the "Secure by Default" motto, to why this system chose proactive security. Make sure your lab is ready, because the Learn OpenBSD journey has just begun!