CompTIA^® A+^™ Core 2 Exam Notes : Basics Of Client-Side Virtualization

Security Requirements

Security for virtualization is important because if somebody gains access to the host, they effectively would gain access to at least parts of all those different operating systems. And if you have a failure of the hardware of that host, then of course all of those other operating systems are not going to work either.

Main security threat in virtualization is to the hypervisor. The VM escaping is a new type of security concern. Because if you can gain access to those virtual machines and then even gain access from one virtual machine to the other through the hypervisor, that's a significant security hole. The bad guys are trying to create malware and find ways to get around and move around that operating system or multiple operating systems much easier than what they can do today. If they can take advantage of the hypervisor, that gives them a very, very useful channel. Both physical and digital security methods are used to ensure security in virtualization

Network Requirements

While it is possible to do desktop virtualization on a computer without an internet connection there are several reasons for which having internet connection is an advantage. First hypervisors can be obtained from internet, and updates to hypervisors, host operating system, guest operating system are easily available on internet. Furthermore, if you create a virtual machine to test an operating system or other software for use in a normal environment, then you certainly should include testing how it works on a network. Therefore, the hypervisors we use simulate a network card within each virtual machine, as well as a network on the host, so that multiple virtual machines can communicate with each other and the underlying host. Then, through a virtual connection to the host computer's physical network adapter, each VM has access to an external network, and through that to the Internet, if available. Of course, you can turn off these and other features for a VM, if you desire.

Hypervisor

To do desktop or server virtualization, you first need a hypervisor. A hypervisor, also called a virtual machine monitor (VMM), is the software that creates a virtual machine, providing access to the necessary hardware on the host machine in isolation from other virtual machines and the host operating system, if present. This allows multiple operating systems to run simultaneously on a single physical computer, such as a network server or desktop computer. A hypervisor must create a virtual CPU compatible with that of the underlying machine-mainly either an Intel or an AMD CPU. This means that the installed OS must be capable of installing directly on the underlying computer. Also, today's hypervisors require, or at least work best on, computers with Hardware-Assisted Virtualization (HAV) features, either Intel Virtualization Technology for x86 (Intel VT-x) or AMD Virtualization (AMD-V). HAV supports and improves the performance of virtual machines on the host. Both Intel and AMD CPUs have supported HAV since 2006.