Virtualization #

It is realy easy to virtualize an operating system with OpenBSD thanks to vmd.

Well, that's nice, but what virtualizing means ?

Instead of installing different OS on different computers, you can install an OS inside your current OS. The virtualizer fake to be a full device and run an OS installed on a disk, which is in this case a simple file.

It is very handy since :

• You can use multiple system simultaneously.
• Each system is independent. If one is compromised, others should be safe. It's better than a chroot.
• Backup is really easy: just copy the disk file.
• It's great to try things.

However, it require more resources.

Before going further, make sure we use the same vocabulary :

• "host" is your server. The host virtualize other systems.
• "client" are hosted systems.

OpenBSD offer 3 tools for virtualization :

• vmd : a daemon to manage multiple clients.
• vmctl : To control clients and sending commands to vmd.
• vmm : To watch over clients.

How to virtualize OpenBSD ? #

Actually, everything is already well documented on OpenBSD's website. This chapter will just focus on a few tips.

You should definitely read OpenBSD's FAQ on this topic 😉.

https://www.openbsd.org/faq/faq16.html

Virtualize debian #

Like most linux distro, you'll have to set the installer and bootloader to start the client with a serial console at speed 15200.

# download debian image
ftp "https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-10.5.0-amd64-netinst.iso"
# create disk
vmctl create -s 50G /var/vm/debian.qcow2 
# start the VM
vmctl start -c -m 1G -L -i 1 -r debian*.iso -d /var/vm/debian.qcow2 debianvm

Choose install menu without validating ⚠.

Press TAB then edit the line to change vga and console parameters:

/install.amd/vmlinuz vga=off initrd=/install.amd/initrd.gz --- quiet console=ttyS0,115200n8 

Press Enter.

After installing and rebooting on the fresh debian install, edit /etc/default/grub so serial console is still used.

GRUB_TIMEOUT=1
GRUB_CMDLINE_LINUX_DEFAULT=""
GRUB_CMDLINE_LINUX="console=tty1 console=ttyS0,115200"
GRUB_TERMINAL="console serial"
GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"

Then reload grub:

# update-grub

Virtualize Alpine Linux #

Alpine Linux is a very light distro.

https://www.alpinelinux.org/

Here again, you need to boot using serial console.

# vmctl create -s 50G /var/vm/linux.qcow2 
# vmctl start -c -m 1G -L -i 1 -r image.iso -d /var/vm/linux.qcow2 linux

When starting virual machine, press "TAB" to see available image (i.e. "lts" or "virt"). Add appropriate parameter to use serial console (facultative):

virt console=ttyS0,115200

Then press Enter and it's all good.

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