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Connecting to a VPN can introduce risks as you expose your machine to others on that same VPN. Fortunately it's easy to increase your personal security.

I work at home with my computer. The folks at work recently told me to join their VPN. If I join, will they be able to see personal information on my computer? If they can, how to stop this?

Yes, they might possibly be able to see things on your computer. Naturally it depends on how you've set it up.

The good news, though, is that it should be possible to reestablish a decent level of security while still connecting to the VPN.

A VPN, or Virtual Private Network, is as it name implies: a way to set up connectivity among two or more computers privately. In fact, even though the computers may be miles apart, except for the speed of the connection it's much like having those computers all in the same room connected together through a hub or switch.

And that's the best way to think of a VPN: as a slower, virtual LAN with all the machines connected to each other.

That's actually a very powerful concept. For example as I sit here in my office I can connect to, share files with, share printers with, and otherwise use the computers at my wife's business 10 miles away. I do that across the internet through the VPN I've set up. All of our machines on that VPN can "see" each other just as if they were actually here on my home network.

Naturally there's a risk.

Since I control all the machines at both ends of this VPN, I know who and what I'm dealing with. If you're connecting to a VPN from work you may have no idea who or what is at the other end, or what they're doing.

In that sense, connecting to a VPN might be considered the same as allowing several untrusted machines to connect to your local network. You don't know what they might do. Other machines on that VPN might be infected with viruses, or your corporate IT department might be inventorying all the machines on the network.

"If there are machines you may not trust on the VPN you're connecting to, just make sure to turn your firewall."

Perhaps that co-worker you annoyed last week might is trying to see what's on your machine. If you have file sharing enabled, it's quite possible that he or she can. Since you're all connected to the same (virtual) network your file shares may be visible to other members of the network.

The solution? Quite simple, actually. If there are machines you may not trust on the VPN you're connecting to, just make sure to turn your firewall.

I'd consider the built-in Windows Firewall sufficient for this, but do be careful to make sure that things like file sharing are appropriately blocked. Some firewalls will allow you to configure file sharing to be enabled locally, but blocked on the VPN. Or, naturally, you could just turn off Windows File sharing entirely if that makes sense for your situation.

In your shoes, doing something along those lines I'd feel just fine about connecting up to that VPN.

Article C3049 - June 8, 2007 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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1 Comment
George Arauz
June 9, 2007 5:12 AM

To be honest, you arent secure on much of anyone online, but a VPN is better than most of what you can use.

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