OpenBSD Virtual Machines - Beginner Guide

OpenBSD Virtual Machines - Beginner Guide

Running OpenBSD as a virtual machine is great for testing, learning, or running services isolated from your main system. Here's how.

Step 1: Install vmd (OpenBSD VM Daemon)

OpenBSD includes a built-in virtual machine system called vmd.

pkg_add vmd - installs the virtual machine daemon

After installation: Start the vmd service:
rcctl enable vmd - start vmd on boot
rcctl start vmd - start vmd immediately

Step 2: Create a Virtual Machine

Create a VM configuration file:
vmctl create name=testvm

This creates:
/etc/vmd/testvm.conf - VM configuration file
/var/vmd/testvm.disk0 - virtual disk image

View the configuration:
cat /etc/vmd/testvm.conf

Typical configuration looks like:

machtype "openbsd-74"
disk0 " /var/vmd/testvm.disk0" {
    size 10G  # 10 GB virtual disk
}
nmd0 "opt_nmd0" {
    # Network configuration
}

Step 3: Start the Virtual Machine

vmctl start testvm - start your VM

What happens: The VM boots, and you'll see a console appear.

To connect to the VM console:
vmctl console testvm - opens the VM console interface

Alternatively, use SSH: If you set up networking in the VM config, you can SSH into the VM.

Step 4: Manage the VM

List your VMs:
vmctl list - shows all defined VMs and their status

Stop a VM:
vmctl stop testvm - gracefully stop the VM

Delete a VM:
vmctl destroy testvm - permanently delete the VM and its disk

Important: destroy removes the virtual disk file cannot be undone!

Resize the disk: Edit the configuration file and change the size, then use
vmctl stop testvm before resizing, or the changes may not take effect properly.

Step 5: Networking for VMs

By default, VMs can communicate with the host and each other.

Bridge networking: Connect the VM to your physical network interface.

In /etc/vmd.conf or per-VM config:
nmd0 "opt_nmd0" { } - enables network interface

Host-only networking: VM can only communicate with the host, not the external network.

Common use cases:
- Testing: Try OpenBSD or other OSes without affecting your main system
- Learning: Experiment with configuration changes safely
- Servers: Run development servers isolated from production

Advanced virtualization topics? Proceed to Lesson 81: Virtual Machines.

Next: OpenBSD Course Conclusion - Beginner Guide

Article author: Arthur Isaev