# cd /etc/yum.repos.d
# wget http://download.virtualbox.org/virtualbox/rpm/rhel/virtualbox.repo
# yum update
# yum install dkms
# yum install VirtualBox-5.1
# usermod -a -G vboxusers ACCOUNT_NAME
https://wiki.centos.org/zh-tw/HowTos/Virtualization/VirtualBox
