Virtual Machines: Application Sandbox
I received an e-mail from my auto insurance agent yesterday containing some forms that I needed to print, sign and return to her. The forms came attached to the message as a multi-page TIFF image (something I’d never seen before). I needed to edit some of the pages before I printed them but none of the image editors that I had installed knew what to do with a multi-page TIFF (they would only let me edit the first page).
I started googling for "TIFF splitter" hoping that I’d find some easy way to split a multi-page TIFF into separate image files. I found all sorts of shady looking shareware that claimed to do what I needed, but I was feeling sort of apprehensive.
This will probably be the only time I ever need to split a TFF and who knows what malware or other junk these shareware programs were going to leave on my system. Was it worth the risk?
If only there were some way to install the program, use it to do what I need and then completely wipe it off my computer. It turns out that there is an easy way to do that: use a virtual machine.
A virtual machine allows you to run an operating system within your operating system while ensuring that anything the happens within the virtualized environment doesn’t impact your actual machine. Each virtual machine gets it’s own virtual hardware stack and runs in a separate window on your desktop.
The screenshot below shows a virtualized Windows XP machine running on top of my Vista desktop.
There are all sorts of neat things that you can do with virtual machines (playing with new operating systems, creating truly safe web browsing environments) but I find that I most often use them to test software that I’m unwilling to install on my actual machine. Whether it’s simply beta software or some questionable application you got off Bittorrent, a VM is the perfect way to give it a spin without jeopardizing your primary system.
In the Microsoft Windows domain, the two big VM applications are Microsoft’s own Virtual PC and VMware Workstation from VMWare. Virtual PC is completely free while VMware Workstation will set you back $189. VMWare has a free application called VMware Player that allows you to run existing virtual machines but won’t allow you to create new VMs (there are a lot of pre-built VMs available for download, but you’re unlikely to find any running a Microsoft OS if that’s what you need). VMWare Workstation has some really nice features missing from Virtual PC (USB support), but the fact that Virtual PC is free and does pretty much everything I need has earned it a spot on my system.
I keep all sorts of of VMs around for different tasks, but I’ve got one named "Crash Burn" that is specifically for running un-trusted software. One of the nice features of Virtual PC (also available in VMware Workstation) is the ability to enable "Undo Disks". With the undo disk enabled, the virtual machine essentially becomes read-only — any changes you make to the system are thrown away as soon as you shut down the VM.
For my crash & burn VM, I installed a fresh copy of Windows XP w/ SP3, installed all the latest service packs and then enabled the undo disks. I can boot that VM, install/run whatever crazy stuff I want and then shut it down safe in the knowledge that it will be back in a pristine state the next time that I need it. It’s the perfect solution for those one-time use applications of "questionable parentage".
TIP: I’ve got a collection of about 12 different virtual machines that I keep on my external hard drive. By default, Virtual PC looks for VM images under the
One Response to “Virtual Machines: Application Sandbox”
Actually, VMWare offers VMWare Server, which is free.
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