Install VirtualBox on CentOS

Recently, I switched to CentOS from Windows as my main operating system. Needless to say, not everything I do from day to day can be accomplished on Linux. I still need access to some features Windows has. Mainly their domain tools, because where I work is built on Windows AD. That's where VirtualBox comes in. On most other Linux distros it is as easy as a simple command line and it is installed. Sure it's not the most up-to date version but it does most of what is required from it. Or, on Debian based systems downloading the latest .deb file from Oracle will do the trick.
It's not so easy on CentOS, but it can be done using yum. To start, you need to open up terminal and switch to the root user. This is pretty straightforward with:

su - 
or
sudo -i

then enter the root password. The next step is to add the RHEL repos.

wget http://download.virtualbox.org/virtualbox/rpm/rhel/virtualbox.repo

then

yum update

Once the update is complete, perform a reboot.

CentOS 5/6/7 need the EPEL repo in addition to the RHEL repos, the commands for that are here:

## CentOS 7 and RHEL 7 ##
rpm -Uvh http://dl.fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-6.noarch.rpm

## CentOS 6 and RHEL 6 ##
rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm

## CentOS 5 and RHEL 5 ##
rpm -Uvh http://dl.fedoraproject.org/pub/epel/5/i386/epel-release-5-4.noarch.rpm

Perform another repo update with

yum update

Next, there are a few prereqrisites that need to be installed before downloading and installing VirtualBox.

yum install binutils gcc make patch libgomp glibc-headers glibc-devel kernel-headers kernel-devel dkms

Then install VirtualBox with:

yum install VirtualBox-5.0

This command automatically creates the vboxusers group and your username must be a part of that group in order for VirtualBox to work. Replace username with your regular username

usermod -a -G vboxusers username

Rebuild the kernel modules for VirtualBox to run:

## CentOS/RHEL 7 ##

/usr/lib/virtualbox/vboxdrv.sh setup

## CentOS/RHEL 6/5 ##

/etc/init.d/vboxdrv setup

If everything went well, you should now be able to launch VirtualBox from either the terminal by typing VirtualBox or by clicking on the icon in the application launcher. Be sure to check the BIOS for enabling Virtualization Support. This wasn't enabled on my desktop at first and VirtualBox wouldn't allow to start any VM's without it enabled.