Importing Existing VMs/OVA’s Into VirtualBox

Before I decided to run a Linux based, headless installation of VirtualBox, I had been running all my virtual machines in VMware Workstation. When it was time to switch I exported a number of virtual machines that I had already built to OVF format. These were servers like Windows with Active Directory, GIT, Ansible, that I didn’t want to go through the hassle of building again from scratch. This post is dedicated to my experience of doing this and some of the post migration work that needs to be performed, such as removing VMware Tools, etc.

Import Existing Virtual Machine Image

Before you get started

One tip before you start. When you import the VM into VirtualBox, it’s possible that the network adaptor information will change. This was definitely the case for me when I migrated from Workstation that used the VMXNET3 driver. My interface was configured as ‘ens33‘ and when I switched to the virtio driver in VirtualBox the device came up as eth0. I was therefore unable to connect to my headless VM. My solution was to fire up the source VM again and copy the ‘ifcfg-ens33‘ in /etc/sysconfig/network-scripts/ to ‘ifcfg-eth0‘ and change any references from ens33 to eth0. Finally, I commented out the UUID line. When I re-imported, I was able to connect the my VM.

Import Virtual Machine

To perform the import I am going to use the VBoxManage import command. This command allows the –dry-run flag to be supplied and will provide details of how the virtual machine will look once it has been imported into VirtualBox. This is useful as it allows us to ensure that the configuration is how we want it to be. The dry run will also provide any optional flags that can be used to influence the import. There are also the global options keepallmacs, keepnatmacs, and importtovdi.

I have some virtual machines that have been exported to OVF format:

So let’s take a look at my Ansible (SG1-ANS001) virtual machine that is running on CentOS 7.x.

The dry run feature represents the virtual machine image as a Virtual system followed by an index. As this image only contains a single virtual machine, only index 0 is present. The VM hardware configuration is listed as units. Therefore, I can go through each unit in turn and ensure that the target machine is configured correctly. From the dry run output there are a number of units that need to be modified. I will build out the command as I go along.

1: Suggested VM name “vm” (change with “–vsys 0 –vmname <name>”)

This will need to be changed to the actual name of the VM, which in this case is SG1-ANS001. I can use the options –vsys 0 –vmname <name> to accomplish this.

5: Network adapter: orig custom, config 5, extra type=Bridged

The original VM was using a custom host-only network interface on the previous hypervisor which is not understood by VirtualBox. The import command is therefore defaulting to a suggestion of a Bridged interface, which is not correct. I need connect the virtual network card to my vboxnet0 host-only interface on VirtualBox. Unfortunately, the import command does not provide an option that I can see which can make this change. I will therefore need to modify the VM once it has been imported.

9: Hard disk image: source image=SG1-ANS001-disk1.vmdk, target path=/mnt/vm2/vbox/vm/vm/SG1-ANS001-disk1.vmdk, controller=7;channel=0

The source disk image is a VMDK, the format used by VMware. Although VirtualBox uses the VDI disk image format, it has defaulted to continue using VMDK. This will still work but as my goal is to move to a fully Open Source solution, converting to VDI makes more sense. The global option importtovdi can be used to achieve this. My command now looks like:

VirtualBox will default to re-initialising the MAC address of all network cards on the VM. I am not interesting in making post configuration changes because of this and my preference would be to preserve the existing MAC addresses that was allocated to the original VM. There is no real reason not to do this. The global option keepallmacs can be used to achieve this. My final command now looks like this:

If we issue another –dry-run against the new command we can see most of the changes have taken effect.

We can now re-issue the command with the –dry-run omitted to perform the import of this virtual machine into VirtualBox. The progress will be displayed and a message if the import was successful:

Post-Import Configuration

Let’s check that we can see the VM in the VirtualBox inventory:

Configure Networking

If you recall from the previous section, we were not able to change the network card binding during the import. We can do this now that the VM has been imported using the VBoxManage modifyvm command. I need to bind to a host-only interface called vboxnet0.

I also want to use the paravirtualized Network Adaptor using the virtio driver for better performance.

The VBoxManage showvminfo command can be used to view the VMs configuration, which can be used to confirm any changes that have been made.

Disable Audio

I noticed from my VBoxManage showvminfo output that an Audio card was enabled.

Audio: enabled (Driver: ALSA, Controller: AC97, Codec: STAC9700)

I do not require this so the card can be disabled:

Set VM Description

While we’re at it, it would probably be a good idea to give this VM a small description.

Virtual Machine Power Operations

Start VM

Since we’re going to be running this VM in headless mode, the alternative binary VBoxHeadless will be used instead of VBoxManage. The VBoxHeadless interface accepts the same start parameters. If you see the copyright information after you have run the command then the VM will have been started successfully.

Use the  VBoxManage list runningvms command to verify that the VM process is actually running.

Stop VM

You can gracefully stop the running VM using the VBoxManage controlvm <vm> acpipowerbutton command.


If you aren’t able to connect to the VM after it has been started then it may have failed to boot or a network configuration issue. As the VMs are running in headless mode it can be difficult to diagnose. There are a couple of decent ways to help diagnose the issue.


This option is simple and takes a screenshot of the console. You can specify the filename to save (in PNG format) then download this via SCP from the VirtualBox host.

Serial Port (console redirect)

I will follow up with an additional post on how the display output can be redirected to the serial port and some cool ways that we can view and interact with this session.

If there is some other configuration that I could apply to my VMs or vbox installation, then please let me know.

CentOS running VirtualBox (headless mode)

Today I started work on something that has peeked my interest for a while, switching my server to CentOS running VirtualBox in headless mode.

I had long been a fan of VMware Workstation, back in the day, it was more feature rich than Vbox and provided better memory management features. Alas, that is not the case today and with VirtualBox’s powerful ‘VBoxManage‘ CLI, it really fits in well where I can write all my infrastructure in code (and yes, I’ll most likely layer Vagrant on top of this). VirtualBox also provides an alternative headless interface ‘VBoxHeadless‘, which means there is no requirement to run a GUI on my server.

As I am starting out on this new journey I felt that it would be great to blog about and hopefully help others that want to do this.

All I have from the start is a minimal installation of CentOS 7.4 (Core). I am using the following as a guide for the VirtualBox installation:

VirtualBox Installation

Install Dependencies

Install Extra Packages for Enterprise Linux (EPEL)

Install Dynamic Kernel Module Support (DKMS)

This will install quite a few packages:

Install Development Tools

I want my server to have access to a basic development environment so we’ll install the group packages for this. This will install packages such as gcc, make, binutils, etc. Use ‘yum groupinfo “Development Tools“‘ to view the entire list of packages installed in this group.

Install Kernel Development

Install VirtualBox

Add the VirtualBox package repository

Install VirtualBox

This will also install a number of dependencies.

Install VirtualBox Extension Pack

The VirtualBox Extension Pack will add support for the following:

  • USB 2.0 and USB 3.0 Host Controller
  • Host Webcam
  • VirtualBox RDP
  • Disk Encryption
  • NVMe

Download the extension pack:

Once downloaded, install the extension pack:

OR, if you are upgrading from a previous version of the extension pack, then you will need to add the ‘–replace’ option to uninstall the old version first.

Agree to the license terms and conditions.

The extension will be installed.

Verify that the extension pack has been installed successfully.

You should see output like the following:

Add Users to ‘vboxusers’ Group

When VirtualBox is installed a new group ‘vboxusers’ is created. Users that are a member of this group will be allowed to run VirtualBox. I will add my non-privileged user to this group.

Verify Installation

VirtualBox Linux kernel module (vboxdrv)

Check that the vboxdrv service has installed correctly and is running.

You should see output like the following:

The status should be ‘loaded‘ and ‘active‘. If you see a ‘Kernel driver not installed‘ message then try running the following command:

VirtualBox Web Service (vboxweb)

Check that the vboxweb service is running:

You should see output like the following:

Configure VirtualBox

Configure Networking

I have some basic network requirements for my lab to start out with. I will use a host-only interface, which will be the management network and a NAT interface, which can be useful for VMs that I want to access the Internet without going through the virtual firewall. I will also need to bridge one of my virtual firewall’s network interfaces to the servers physical interface (so that I can do some additional routing on my physical network).

I can see what network interfaces are currently available using nmcli.

Create the Host-Only Interface

We can confirm that the Host-Only interface was successfully created using nmcli.

Assign Network to Host-Only Interface

To confirm that the IP address has been assigned, use the ip command.

Create NAT Interface

I want to create a NAT network on and have IP addresses allocated to clients automatically using DHCP.

To confirm that the NAT network has been created use the following command.

We can see that the network has been created and an IP address has been allocated automatically for the gateway (uses the first available address). This should be enough to provide outbound Internet access to any VM NICs attached to this interface.

Global Settings

I also like to configure some global settings so that I do not need to keep specifying these when creating new virtual machines.

Default Virtual Machine Folder

I actually have 2 large SSDs that I spread the VMs across for IO reasons. I will default to one of these and manually specificity my second disk when required.

Exclusive Hardware Virtualization

VirtualBox will be given exclusive use of the hardware virtualization extensions (Intel VT-x or AMD-V). I think this defaults to on but let’s set it anyway.

Default Front End

I am not running a GUI on this server so all virtual machines will be running in headless mode.

That concludes my initial setup and now I am ready to start deploying my virtual machines. I will provide posts on my new virtual machine deployments as I build out my new infrastructure using VirtualBox. I also have a number of OVF’s that I exported from my old environment that I’ll be importing and will document the steps along the way.