Is anonymous web surfing possible? If so, can't the 'bad guys' use it too?

Every computer on the internet is, ultimately, identified by its IP address. Whenever one computer connects to another, each "knows" the others IP address. It's how data is routed across the internet from one computer to another.

So, for example, when I visit a web site such as this one, the server "knows" and records my internet IP address.

Now, I've spend a lot of time on this site discussing how IP tracing is not possible for mere mortals. You and I cannot trace an IP address to the physical location of the computer it represents. At best, you and I can find out the ISP that has assigned that IP, and perhaps the general region that the IP address is located in.

But the ISP - well, that's different. They can trace the IP address to the exact location of the computer connected to it. They'll typically only do it in response to a law enforcement request or court order, but they can do it.

That's where anonymous surfing services come in.

An anonymous surfing program runs all of your web traffic through a third computer. Instead of connecting your computer to a web site directly, you connect to the service, and the service connects to the web site on your behalf. All data is funneled through the service.

This "anonymizes" you, because the web site you're visiting never sees your IP address. All they see is the IP address of the anonymization service.

Now, conceptually that's all very simple. But there are issues...

• Your IP address is visible to the anonymization service: that's required for your connection to work. You are trusting that they are not logging your connection and logging who you're connecting to. You're further trusting that they won't reveal any of that to anyone else.

• The service's IP address is visible: possibly making it obvious that you are using an anonymization service. That might make it look like you have something to hide.

• Your IP address may not be the only thing that identifies you (#1): there's often other information included when you make a request that could identify you or could at least help distinguish your visits from someone else. Torpark addresses this by actually including Firefox to be used in conjunction with Torpark. Other services may, or may not, address this at all.

• Your IP address may not be the only thing that identifies you (#2): as we saw with the recent search data "accidentally" released by AOL, you may not need an IP address to be identified. Many individuals were identified solely by the search queries that they made. As always, be careful with what information you provide as you browse; search terms, URLs, form information - individually they might mean nothing, but taken in aggregate you might be leaving an identifiable trail.

• The services tend to be slow: The very nature of adding a computer "in the middle" of your web requests adds time and makes things slower. I've tried several anonymous surfing tools over the past few years, and each has been noticeably, if not unacceptably, slow.

And one other issue you touch on with your question: Anyone can us 'em. Are there social implications if everyone can surf without accountability? Using the currently semi-inflammatory example, does this technology enable terrorists to operate without being caught?

As always, the answers are not that simple.

First realize that anonymization services are not new. They've been around for years already.

The fact is that anything can be traced if you have sufficient resources, and especially if you have the backing of the government. But what are "sufficient resources"? As I mention above, the practical reality is that sufficient resources are well beyond the means of most people on the internet. Doing so legally means having a legal reason, and the support of an already over-taxed legal system to back you up. Doing so illegally starts to look like some kind of spy movie - except it takes much more energy and time than Hollywood would lead you to believe.

It's typically just not worth it. Web surfing is already mostly anonymous anyway - not because it can't be traced, but because there's no one who cares to take the time and effort to do the tracing.

Anonymous surfing services simply put up another barrier to detection. But if the people attempting to track it are sufficiently motivated and have the resources (I would expect HUGE resources) - then it wouldn't surprise me at all if it's a barrier that could be breached, or at least shut down.

But I personally don't expect that to happen often at all.