Police in England have arrested a Nottingham man accused of running a proxy server that provides access to sites subject to court-mandated blocks.

The man - who has since been released on bail - was accused of running the Immunicity proxy service [Broken URL Removed], which has been taken down by the authorities. This was designed to unblock torrent sites by sending traffic through various different proxies, depending on the URL you were looking for.

The arrest was made after police - in conjunction with the Federation Against Copyright Theft (FACT) - found evidence that Immunicity was providing access to 36 websites that had been previously been blocked in the UK for infringing copyright.

Immunicity allowed users to access sites that have been blocked by a number of European ISPs in recent years, including the seemingly invincible The Pirate Bay, which was blocked in 2012 after a High Court ruling. This resulted in Immunicity being in breach of anti-circumvention provisions in UK copyright law.

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The Immunicity website has since been taken down. In its place is an intimidating notice from the City of London Police informing visitors that the site is subject to a criminal investigation. The notice also links to a number of commercial websites where music and movies can be obtained legitimately.

Curious about what the take-down of Immunicity means for you? Read on for more.

How Immunicity Worked

It was quite impressive to see how Immunicity circumvented ISP level blocking of websites. It required users to modify their browser settings with something called a Proxy Auto-Configuration (PAC) File.

PAC files are old-hat. They've existed since the release of Netscape 2.0, and have remained in use ever since. They consist of little more than a few lines of JavaScript and function like any other forward proxy.

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They instruct your browser to forward specified network requests through different addresses. These addresses contain a proxy server, which return the site you're interested in.

This replaces what would normally happen when you type in an address into your browser; where a a DNS request is made, your browser then retrieves the content and then presents it to you.

Immunicity offered a PAC file that forwarded requests to blocked torrent sites - including The Pirate Bay, EZTV and KickAssTorrents - to its own servers, effectively circumventing ISP level blocks.

Interestingly, the PAC file also allowed users to circumvent blocks on a number of legitimate websites that stream adult content. One can only wonder if this was intended to circumvent the blocks found in most workplaces, or the new opt-out web filtering that is mandatory for all new Internet subscriptions in the UK.

This PAC file has been saved for posterity on Pastebin, thanks to Reddit user jomkr.

Are VPN Users Safe?

At first glance, this sounds worryingly similar to what a Virtual Private Network (VPN) does. A VPN allows users to circumvent ISP level restrictions by funneling traffic through an encrypted tunnel to an endpoint where it is not subject to these restrictions.

This also has the advantage of allowing users to circumvent ISP level surveillance, as traffic is strongly encrypted before transmission. This means that it is impossible to determine whether the user is using a protocol typically associated with copyright infringement - such as Bittorrent or with the decentralized eDonkey network - or visiting sites that are typically associated with mass copyright infringement.

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However, there's a number of crucial differences between traditional VPN services and Immunicity. Differences that make one legal, and another illegal.

Firstly, Immunicity's servers only accepted requests for specific websites. If a user edited the PAC file to add another website, it would simply error out, or refuse to process the request. In short, Immunicity were specifically providing access to websites that had been blocked by court order, or were known to facilitate copyright theft.

Furthermore, VPNs are what could be described as a dual-use technology. Sure, you could use them to access The Pirate Bay and grab the latest episode of Game Of Thrones, just as much as you could use them to privately and securely check your e-mail in the airport.

Whereas Immunicity was a service that had no other legitimate usage, a design fault that would later prove to be its undoing.

This means that your favorite VPN service isn't about to be shut down. They're safe, and so are other services like Hola, which offer a browser-integrated VPN

Now Is A Bad Time To Launch A Circumvention Service

Months after the High Court ruled The Pirate Bay was to be blocked in the UK, the UK Pirate Party launched its own proxy service. After a few short months, it defiantly waved fingers in the face of this deeply unpopular court order. And then, it was promptly shut down under the threat of legal action.

Other proxies have suffered a similar fate. Immunicity is not alone in finding itself on the wrong side of the law. In a quote to Wired Magazine, the head of the City of London Police's Intellectual Property Crime Unit said "We will come down hard on people believed to be committing or deliberately facilitating such offenses".

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It seems that the age of the pirate proxy is over. But there are alternatives.

Firstly, you can roll your own proxy server. All you need is a VPS (I recommend Digital Ocean), an installation of NGINX, and the Pirate Bay Proxy PHP script available from Github.

You can also invest in a VPN. Some of these have the advantage of not retaining any logs of your Internet activity, and tend to cost just a few dollars per month.

There's also a Chrome and Firefox plugin called Hola. This allows you to selectively push your network traffic through VPN endpoints, allowing you circumvent ISP level blocking, in addition to annoying region restrictions.

Or, you can go legit and kick the piracy habit for good. Can't be bothered paying for music? Spotify has a free plan. You can also get your movies and TV fix through the likes of Netflix, iPlayer, and Hulu, if you're based in the United States.

Immunicity Has Gone - What Are You Going To Do?

Were you a long-time user of Immunicity? Have you got an especially novel way of circumventing censorship? Tell me about it. The comments box is below.

Photo Credit: Gil C / Shutterstock.com