headless server:

tested: 2018-10-17 on CentOS Linux 7.5 (Core)

wget https://www.virtualbox.org/download/oracle_vbox.asc
rpm --import oracle_vbox.asc
cd /etc/yum.repos.d/
wget https://download.virtualbox.org/virtualbox/rpm/el/virtualbox.repo
yum update
yum search virtualbox
yum install VirtualBox-5.2.x86_64
# if you want/need usb 3.0 extension package
wget https://download.virtualbox.org/virtualbox/5.2.20/Oracle_VM_VirtualBox_Extension_Pack-5.2.20.vbox-extpack
VBoxManage extpack install Oracle_VM_VirtualBox_Extension_Pack-5.2.20.vbox-extpack 

manpage of vboxmanage:

if you have a gui like debian2 mate pre installed:

1. https://dwaves.org/2017/06/30/centos-redhat-compiling-the-latest-kernel/

2. checkout what is the latest version of VirtualBox for your System: https://www.virtualbox.org/wiki/Downloads

su; # become root

mkdir /software;

cd /software;

wget https://download.virtualbox.org/virtualbox/5.2.6/VirtualBox-5.2-5.2.6_120293_el7-1.x86_64.rpm

rpm -i VirtualBox-5.2-5.2.6_120293_el7-1.x86_64.rpm; # install

# add DefaultNonRootUser to group of vboxusers, to allow usage
usermod -a -G vboxusers YourDefaultNonRootUser;

in order to use anything faster than USB 1.1 you will need to install the extension pack.

wget https://download.virtualbox.org/virtualbox/5.2.6/Oracle_VM_VirtualBox_Extension_Pack-5.2.6-120293.vbox-extpack

go to preferences

and hit + to add it

admin