VBoxHeadless – Running Virtual Machines With VirtualBox 4.0 On A Headless CentOS 5.6 Server

This guide explains how you can run virtual machines with VirtualBox 4.0 on a headless CentOS 5.6 server. Normally you use the VirtualBox GUI to manage your virtual machines, but a server does not have a desktop environment. Fortunately, VirtualBox comes with a tool called VBoxHeadless that allows you to connect to the virtual machines over a remote desktop connection, so there's no need for the VirtualBox GUI.

I do not issue any guarantee that this will work for you!


1 Preliminary Note

I have tested this on a CentOS 5.6 server (host system) with the IP address where I'm logged in as a normal user (user name admin in this example) instead of as root.

If you only have a root account, but no normal user account, create one as follows (user admin, group admin)…

# groupadd admin
# useradd -d /home/admin -m -g admin -s /bin/bash admin

… create a password for the new user…

# passwd admin

… and log in as that user.


2 Installing VirtualBox

To install VirtualBox 4.0 on our CentOS 5.6 server, we need root privileges, therefore we run

$ su

Now we enable the RPMforge repository on our CentOS system as the dkms package (Dynamic Kernel Module Support Framework– this package is needed to build the VirtualBox kernel module) that we are going to install is not available in the official CentOS 5.6 repositories:

# rpm –import http://apt.sw.be/RPM-GPG-KEY.dag.txt

# cd /tmp
# wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el5.rf.x86_64.rpm
# rpm -ivh rpmforge-release-0.5.2-2.el5.rf.x86_64.rpm

(If the above link doesn't work anymore, you can find the current version of rpmforge-release here: http://packages.sw.be/rpmforge-release/)

Then we install the dependencies for VirtualBox 4.0 as follows:

# yum groupinstall 'Development Tools'

# yum groupinstall 'Development Libraries'

# yum install SDL kernel-devel kernel-headers dkms

With the last command we have installed the kernel headers of our currently used kernel. The headers are located in the /usr/src/kernels/ directory, but it is likely that its directory is not named <kernel_version>-<architecture>, but has a different name so that the Virtualbox kernel module cannot be built later on because the expected kernel headers directory cannot be found. We are going to correct that now:

Check your kernel version…

# uname -r

[root@server1 kernels]# uname -r
[root@server1 kernels]#

… and architecture:

# uname -m

[root@server1 2.6.18-238.el5]# uname -m
[root@server1 2.6.18-238.el5]#

This means that there should be a directory called 2.6.18-238.el5-x86_64 in the /usr/src/kernels/ directory. We can check this now:

# cd /usr/src/kernels/
# ls -l

[root@server1 kernels]# ls -l
total 4
drwxr-xr-x 19 root root 4096 May 19 14:26 2.6.18-238.9.1.el5-x86_64
[root@server1 kernels]#

As you see, I have the directory 2.6.18-238.9.1.el5-x86_64, but not 2.6.18-238.el5-x86_64. Therefore we create a symlink called 2.6.18-238.el5-x86_64 that points to 2.6.18-238.9.1.el5-x86_64:

# ln -s 2.6.18-238.9.1.el5-x86_64 `uname -r`-`uname -m`

Next download and register the VirtualBox public rpm key:

# wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc
# rpm –import oracle_vbox.asc
# rm -f oracle_vbox.asc

Now we enable the VirtualBox CentOS repository on our system:

# cd /etc/yum.repos.d/
# wget http://download.virtualbox.org/virtualbox/rpm/rhel/virtualbox.repo

We can now simply install VirtualBox 4.0 as follows:

# yum install VirtualBox-4.0

If the installation is successful, the output should end as follows:

Running Transaction
  Installing     : VirtualBox-4.0                        1/1

Creating group 'vboxusers'. VM users must be member of that group!

No precompiled module for this kernel found — trying to build one. Messages
emitted during module compilation will be logged to /var/log/vbox-install.log.

Stopping VirtualBox kernel modules [  OK  ]
Uninstalling old VirtualBox DKMS kernel modules [  OK  ]
Trying to register the VirtualBox kernel modules using DKMS [  OK  ]
Starting VirtualBox kernel modules [  OK  ]

  VirtualBox-4.0.x86_64 0:4.0.8_71778_rhel5-1

[root@server1 kernels]#

(If the installation fails because the correct kernel headers directory cannot be found, output will end as follows:

Creating group 'vboxusers'. VM users must be member of that group!

No precompiled module for this kernel found — trying to build one. Messages
emitted during module compilation will be logged to /var/log/vbox-install.log.

Stopping VirtualBox kernel modules [  OK  ]
Uninstalling old VirtualBox DKMS kernel modules [  OK  ]
Trying to register the VirtualBox kernel modules using DKMS
Error! Your kernel headers for kernel 2.6.18-238.el5 cannot be found at
/lib/modules/2.6.18-238.el5/build or /lib/modules/2.6.18-238.el5/source.
  (Failed, trying without DKMS)
Recompiling VirtualBox kernel modules [FAILED]
  (Look at /var/log/vbox-install.log to find out what went wrong)

  VirtualBox-4.0.x86_64 0:4.0.8_71778_rhel5-1

[root@server1 yum.repos.d]#

In this case, try to create the correct kernel symlink (as shown before) and then run

# /etc/init.d/vboxdrv setup

to create the VirtualBox kernel module.)

Now we must add the user that will run VirtualBox (admin in this example) to the vboxusers group:

# /usr/sbin/usermod -G vboxusers admin

VirtualBox is now installed and ready to be used.


# exit

to leave the root account and become a normal user (admin) again.


3 Using VirtualBox On The Command Line

3.1 Creating A VM

To create a VM on the command line, we can use the VBoxManage command. See

$ VBoxManage –help

for a list of available switches and (highly recommended!) take a look at http://www.virtualbox.org/manual/ch08.html.

I will now create an Ubuntu 11.04 Server VM with 512MB memory and a 10GB hard drive from the Ubuntu 11.04 Server iso image (which I have stored in /home/ubuntu-11.04-server-amd64.iso):

$ VBoxManage createvm –name "Ubuntu 11.04 Server" –register
$ VBoxManage modifyvm "Ubuntu 11.04 Server" –memory 512 –acpi on –boot1 dvd –nic1 bridged –bridgeadapter1 eth0
$ VBoxManage createhd –filename Ubuntu_11_04_Server.vdi –size 10000
$ VBoxManage storagectl "Ubuntu 11.04 Server" –name "IDE Controller" –add ide
$ VBoxManage storageattach "Ubuntu 11.04 Server" –storagectl "IDE Controller" –port 0 –device 0 –type hdd –medium Ubuntu_11_04_Server.vdi
$ VBoxManage storageattach "Ubuntu 11.04 Server" –storagectl "IDE Controller" –port 1 –device 0 –type dvddrive –medium /home/ubuntu-11.04-server-amd64.iso


3.2 Importing An Existing VM

Let's assume you have a VM called examplevm that you want to reuse on this host. On the old host, you should have a directory Machines/examplevm in the VirtualBox directory; Machines/examplevm should contain the examplevm.xml file. Copy the examplevm directory (including the examplevm.xml file) to your new Machines directory (if your user name is admin, this is /home/admin/.VirtualBox/Machines – the result should be /home/admin/.VirtualBox/Machines/examplevm/examplevm.xml).

In addition to that copy the examplevm.vdi file from the old VDI directory to the new one (e.g. /home/admin/.VirtualBox/VDI/examplevm.vdi).

Afterwards, you must register the imported VM:

$ VBoxManage registervm Machines/examplevm/examplevm.xml


3.3 Starting A VM With VBoxHeadless

Regardless of if you create a new VM or import an old one, you can start it with the command:

$ VBoxHeadless –startvm "Ubuntu 11.04 Server"

(Replace Ubuntu 11.04 Server with the name of your VM.)

VBoxHeadless will start the VM and a VRDP (VirtualBox Remote Desktop Protocol) server which allows you to see the VM's output remotely on another machine.

To stop a VM, run

$ VBoxManage controlvm "Ubuntu 11.04 Server" poweroff

To pause a VM, run

$ VBoxManage controlvm "Ubuntu 11.04 Server" pause

To reset a VM, run

$ VBoxManage controlvm "Ubuntu 11.04 Server" reset

To learn more about VBoxHeadless, take a look at

$ VBoxHeadless –help

and at http://www.virtualbox.org/manual/ch07.html#vboxheadless.

4 Connecting To A VM From A Remote Desktop

4.1 Windows XP


You can use the built-in Remote Desktop Connection utility to connect to the VM:

Type in the hostname or IP address of the host (not the guest!):

And voilà, you should be connected to the VM:


4.2 Linux

On Linux desktops, you can use the rdesktop command to connect to the VM. I'm assuming you're using a Fedora 14 desktop here.

On Fedora 14, you must install rdesktop first. Open a terminal (Applications > System Tools > Terminal)…

… and become root:

$ su

Then install rdesktop

# yum install rdesktop

… and leave the root shell:

# exit

Then type in the following command:

$ rdesktop -a 16

( is the host IP address, not the one of the guest – replace it with your own IP address or hostname; -a 16 means 16 bit colour depth.)

And voilà, you should be connected to the VM:


4.3 If The Remote Desktop Connection Doesn't Work…

If the remote desktop connection doesn't work, you've probably missed the step where I install the VirtualBox extension pack in chapter 2. Please install the extension pack now, stop your virtual machine (see chapter 3.3), and modify your virtual machine to accept remote desktop connections:

$ VBoxManage modifyvm "Ubuntu 11.04 Server" –vrde on

(If the extension pack is already installed when you create your virtual machine, remote desktop connections are automatically enabled.)

Then start your virtual machine again.




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