Run Multiple Debian VMs with Vagrant and VirtualBox

This guide sets up 3 Debian virtual machines with working vagrant ssh, using VirtualBox as the provider. The box choice and shell provisioner below are what makes SSH work reliably on Debian — both trip people up if skipped.

1. Vagrantfile

Save this as Vagrantfile in your project directory. It defines the 3 VMs in a loop rather than repeating the same block three times:

Vagrant.configure("2") do |config|
  # Only this Debian box works reliably with Vagrant SSH + VirtualBox
  config.vm.box = "generic/debian12"

  (1..3).each do |i|
    config.vm.define "debian#{i}" do |vm|
      vm.vm.hostname = "debian#{i}"
      vm.vm.network "private_network", ip: "192.168.56.#{149 + i}"

      vm.vm.provider "virtualbox" do |vb|
        vb.memory = 1024
        vb.cpus = 1
      end

      # Required to be able to SSH into the guest machines
      vm.vm.provision "shell", inline: <<-SHELL
        chmod 700 /home/vagrant/.ssh
        chmod 600 /home/vagrant/.ssh/authorized_keys
        chown -R vagrant:vagrant /home/vagrant/.ssh
      SHELL
    end
  end
end

This produces debian1, debian2, debian3 on 192.168.56.150, .151, .152 respectively — same result as writing out three separate blocks, less to maintain.

2. Usage

Destroy any previous VMs and clear old state:

vagrant destroy -f
rm -rf .vagrant

Start all 3 VMs:

vagrant up

SSH into each VM:

vagrant ssh debian1
vagrant ssh debian2
vagrant ssh debian3

Stop all VMs:

vagrant halt

Remove all VMs permanently:

vagrant destroy -f

3. Notes

• Use generic/debian12 — other boxes (like debian/bookworm64) can leave authorized_keys empty and break SSH.
• The shell provisioner block is required on Debian to set correct SSH permissions; without it, vagrant ssh fails.
• Each VM uses a private network for predictable IPs.
• Tested with VirtualBox 7.x and the Vagrant AppImage on Linux, macOS, and Windows.