Virtual PCs are the key to secure computing

Cloned machines are immune from threats, says Tom Yager

For readers’ convenience, I’d like to summarise the long list of present best practices in client-system security implemented by all InfoWorld US readers.

When you sit down at a client computer that’s not hooked into a locked-down corporate network, there’s a drill. There are email rules that block potentially hazardous attachments, including JPEGs and Office documents.

Firewalls are cranked up to maximum vigilance, getting clearance for every attempt by every application to open an outbound TCP/IP connection. Antivirus software runs constantly and stays constantly updated. You set aside temporary mail accounts for use in forums, Usenet posting and online shopping to avoid phishers and spammers.

Cookies, Javascript, auto-fill and plug-ins disabled in your browser and use of IM or peer-to-peer networks is forbidden. You regularly clean out your Windows registry or sweep out the detritus of installed but unused Linux or OS X software, and files that have piled up in Firefox’s cache and download directories are weeded out.

For anyone who doesn’t do all of these things, their sloth will be their undoing. Those who do take all of these measures are either very wise or non-life-having nutcases who don a helmet to drive a car. Unless you’re a monk or you don’t have your system’s local administrator or root password, then impatience and a desire to work, create and play unimpeded will eventually win out.

The solution is simple: maintain parallel paranoid and promiscuous selves and give each its own computer. Your promiscuous self is open and daring, a slave to impatience, likes talking to strangers and is too busy being productive and enjoying life online to keep your place spotless and run the neighbourhood watch. Your paranoid self regards your computer as a vessel for your electronic soul, your ambassador for official communication, the keeper of your secrets that scorns unfamiliar visitors.

One’s physical computer should always be configured like a server, as paranoid as you can tolerate, and like a server, left untouched except by your paranoid self. Your promiscuous self can have free run of a largely unsupervised playground operating in a virtual machine. Your devil-may-care persona’s email client has HTML viewing enabled and is configured to access only spam accounts. On the virtual machine, you run browsers wide open so you don’t have to constantly click through barriers to get where you want to go, and you’re even free to share files, use IM, run BitTorrent and host a website and mail server. These are facilities you don’t even install on the host.

If a physical host is adequately protected, and the virtual machine guest does not use a bridged connection through the host to get to the internet, then a virtual machine guest cannot harm its host. The only link between the guest and host should be an isolated shared folder owned by an unprivileged user with no login access.

If the promiscuous virtual machine gets infected or its trash piles up, the fix is simple as long as you plan ahead. After finishing configuring your guest OS and applications, but before reaching out to the net, clone your guest’s disk image. When things get untidy or unsafe in the guest, just boot from the clean clone, mount the fouled guest image as a secondary drive and copy over the files you need as you need them. IT people secretly want to implement best practices in the organisation and exempt themselves from them. Now you can, too — without being a hypocrite.

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