The Scoop on Virtualization

Virtualization is the term given to the process of emulating the characteristics of a computer resource so that applications and users may interact with it. The most common example is running one operating system on top of another operating system.

Virtualization has been used in different forms for a long time, another common example being the use of software to emulate your computer's Random Access Memory (RAM) so that it appears bigger to applications. An increasing trend today is platform virtualization, where a simulated environment is set up for a guest application to run in. Thus, the "host" system runs "guest" applications in a "virtual machine", with the guest application completely oblivious of the fact. For example, if you have a Windows operating system running on one laptop and you install a virtualization software, like VMware , on a second laptop, this would create a virtual environment to install different operating systems on the second laptop. This implies, for example, that you can install different distributions of Linux operating systems in the VMware environment and each installation behaves as an independent installation or operating system.

Virtual machines have gained popularity both in the academic and professional world. They offer a cost-effective mechanism for gaining the use of multiple computer resources with little investment. They are especially useful in distributed or networked applications and in applications where a large number of nodes are required. A single physical machine may run multiple copies of virtual machines on it, which share the same physical memory and resources, but otherwise run independently of each other.

A popular use of virtual machines among students is to run different operating systems; different applications run better in different operating systems, and virtualization offers the user the ability to emulate, say, a Linux operating system on a computer with Windows installed. Hence, a user could work in a Linux environment if he wanted to without actually installing the operating system on his machine.

Virtual machines are also very useful in security research, as they offer an enclosed secure environment for testing and research of potentially harmful processes. Since everything is contained within the virtual sandbox, one can, for example, safely study the behavior of a particularly nasty virus, without running the risk of infecting critical resources with it. Any harm caused by such a virus is confined to the virtual machine, while the host operating system remains unaffected.

This security property has attracted the attention of many companies seeking relatively secure, inexpensive deployment on shared physical resources. For example, a company can deploy multiple web servers on different virtual machines on a single physical node. Even if a single server is compromised or encounters errors, the others remain unaffected, by virtue of separation. The virtual machine is custom-built to the operating system that it runs, and therefore presumably offers much better performance and reliability. However, there are those who claim that deploying services on virtual machines increases security risk instead of decreasing it; they claim that using virtual applications exposes the users to vulnerabilities in both the application and virtualization software itself.

Viruses often meet their fate in virtual servers where IT staff test applications and then destroy the server once the malware is detected. People who write viruses are aware of this, and have begun creating special "virtual-aware" viruses that can tell when they're in a virtual environment. Though they've mostly used this knowledge to hide so far, the viruses could easily be adjusted to attack virtual servers' vulnerabilities instead. According to research by the antivirus company ESET, more than 200,000 pieces of virtual-aware malware were at large in November 2008. What this means is that if you're running virtual servers, virus protection is especially critical. There are both pros and cons to using this approach, and neither has conclusively proved itself yet.

Companies offering virtualization software:

• VMware 
• Parallels

References

• Introduction to Virtualization  (KernalThread)
• Virtualization Basics  (VMware)
• Hidden Risks of Virtual Appliances  (Virtualization.info)

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