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For various reasons firewall vulnerability tests can be alarming. Issues they report can be actual problems, or not, depending on your situation.

I found several firewall testers on the net and Windows Firewall (+ Internet explorer on some of them) failed ALL of them. Is this legit? If so, what good is Windows Firewall? I used to use AVG, and McAfee, but they created so many processes and hogged so much time, everything slowed to a halt.

I don't know the specific tests you may be using, but in all honesty it doesn't surprise me.

It really depends on what they mean by "failed", and what you mean by "legit". The real question is do you have anything to worry about. Quite often those tests don't give you a straight answer. Even my favorite test tends to overstate the risk.

So, what to do?

One thing to remember is that if your firewall test is provided by a firewall provider, they of course have an incentive to make your current situation appear dire, and in need of their product.

My favorite test site is GRC's Shields Up. The bad news: it's difficult to navigate, slightly difficult to understand, and definitely what I would consider to be somewhat alarmist. However, it's authoritative and unbiased.

But here's the problem with this, and I would assume pretty much any of the firewall testers...

I ran it, and got the message (in big red letters, no less) that I had "FAILED".

Now as you can imagine, I consider my setup pretty darned secure. And yet it's somewhat disconcerting to see that big red FAILED.

So how had my setup "failed"? To try and keep it from getting too technical, a single port tested on my router responded to an external probe, saying that it was "closed" and not accepting connections. All other ports didn't respond at all. Not responding at all is considered preferable since any response, even a response that says "go away" confirms the existence of something at that address.

Now, is that a failure? Depends on what you're looking for. It's certainly not a failure or a risk to me and as a result I honestly don't care. But it means actually examining the results and understanding the so-called failure.

"If you're at all concerned, I really recommend using a NAT router."

And therein lies the problem. I'm behind a NAT router, which when running properly provides all the firewall I feel I need. Testing with a vulnerability test like Shields UP is nice, but in reality I'd feel just as secure had I not tested just knowing how NAT routers work.

With a software firewall, like the Windows firewall, things are different. Without knowing what kind of failures the tests are reporting it's difficult to know if you have a problem or not. The solutions more often than not are not a different software firewall, but rather understanding the vulnerabilities exposed and changing system configuration to resolve them. A good example might be Windows File Sharing. You could have that enabled through your firewall - but if you're connected to the internet, that's a vulnerability you'll want to close by either disabling that functionality, or closing the hole in the firewall. Other failures may not be as concerning, and may require no real action in practice.

If you're at all concerned, I really recommend using a NAT router. Normally a router would be used to share a single internet connection among more than one computer, but even when used with a single computer it provides a very effective firewall without installing any additional software on your machine.

Article C3045 - June 3, 2007 « »

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
Russ Horton
June 3, 2007 5:51 PM

Thanks, Leo. When I got to thinking about it, I "felt" what you stated, but wasn't sure. A friend who is fairly current in computer security suggested the Linksys WRT55AG Dual-Band Wireless A+G Router for my little home system.

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