Virtualization is a great tool for security professionals, or anybody looking to learn more about security or IT. For little to no cost you can setup a number of servers/systems to learn new operating systems, test out servers before you put them into production or practice your pentesting skills in a safe environment. This is going to be a quick run down for people who don’t know much about virtualization.
What is virtualization? Computer virtualization is the process of taking a physical system and logically breaking it up, so that it can be used by multiple virtual systems. This is typically done in two different ways. One way to use virtualization is by installing a piece of software such as VirtualBox or VMware Workstation on top of an existing operating system. Microsoft even provides built-in virtualization software (Hyper-V) in some versions of Windows, starting with Windows 8.1. Using any of these products allows you to create a fully functional computer/server on top of your existing operating system. The virtual machine can be turned off and on as you please, and even have its own IP address on your network.
Another method of virtualization is called bare-metal, where a virtualization software/Operating System (OS) is installed directly on the hardware to provide virtualization services. VMware ESXi, Microsoft Hyper-V and XenServer are examples of bare-metal virtualization platforms. What you create with virtualization software are Virtual Machines (VMs). Virtual machines behave just like independent computers/servers. Networking options vary by virtualization product, but for the most part you can either keep the virtual machine isolated, or have it run right on your existing networks.
Virtualization for Free The best thing about virtualization is that there are a lot of free options available, some of them are even business grade.
VirtualBox Sun has VirtualBox, which is an open source virtualization software available for Windows, Linux and Mac. It is a great free alternative to VMware Workstation. If you are just getting started with vitalization I recommend VirtualBox. It is free and runs on Windows, OSX and Linux.
Hyper-V If you are in love with Windows you should have your head checked, but you can use this guide from the Techrepublic.com to get started with Hyper-V on Windows 8 or newer Hyper-V.
Getting Started with Hyper-V Tech Republic guide
XenServer is an open source bare-metal virtualization platform, but is better suited for a work environment or for more advanced users.
This has been a quick overview of what virtualization is and free software options for getting started with virtualization.