We’ve been hearing a lot about website-blocking recently, particularly with anti-piracy organizations forcing Internet service providers to block access to The Pirate Bay in the UK and elsewhere. However, when UK Internet service provider BT blocked The Pirate Bay, the block was only in effect for a few minutes before The Pirate Bay bypassed it.

How exactly do supposedly blocked websites like The Pirate Bay remain accessible to so many people, in spite of all the efforts to block them? The answer lies in the way the Internet works.

How Websites Are Blocked

When you load a website – say, by going to thepiratebay.org – your computer contacts its domain name system (DNS) server and locates the numerical IP address associated with that website. The DNS server responds with the website’s IP address and your computer contacts the IP address. Domain names like thepiratebay.org and makeuseof.com are human-readable shortcuts that DNS servers translate to numerical IP addresses.

Blocking can cut off access at the DNS level or block access to the website’s IP address itself. Your Internet service provider runs your default DNS servers, so it can modify them and point thepiratebay.org or another domain name to a “Blocked” page.

There are several ways around this – you can switch your DNS server to an alternative DNS server that isn’t run by your Internet service provider (ISP), such as Google DNS or OpenDNS. You could also visit the website’s IP address directly – for example, 194.71.107.80 is one of The Pirate Bay’s IP addresses, so you can access The Pirate Bay by plugging this number into your web browser’s address bar.

Blocking can also cut off access at the server level. To prevent people from using the above methods to get around the blocks, ISPs can block access to specific IP addresses, preventing their users from communicating with the IP addresses entirely.

How Websites Bypass Blocks

If only DNS blocking is occurring, websites can tell their users to switch DNS servers or access specific IP addresses directly. Even if specific IP addresses have been blocked, a website can quickly add a new IP address that point to the website.

For example, after The Pirate Bay’s IP addresses were blocked, The Pirate Bay immediately added several new IP addresses that pointed to their website. While users could no longer access thepiratebay.org or 194.71.107.80, The Pirate Bay was now also available at 194.71.107.82.

A Pirate Bay representative told Torrent Freak that “they can continue adding new addresses for years to come.” It’s like whack-a-mole – when an ISP blocks an address, a new one immediately springs up.

Legal System Slowness

Compounding the problem for those who would block websites is the way the legal system works. The blockers often require court orders to block specific domains and IP addresses. Some of these court orders may allow the blockers – anti-piracy groups in the case of The Pirate Bay – to add new IP addresses to the block on short notice, while some do not. As some ISPs in the Netherlands responded when Dutch anti-piracy group BREIN told them to block The Pirate Bay’s new IP addresses – “we will do not comply without a court order”.

Even if all court orders allowed anti-piracy groups to block new IP addresses without going through the legal system again, court orders would have to be obtained in a variety of countries against a large amount of ISPs. On the other hand, The Pirate Bay can add a new IP address accessible to the entire world and circumvent the block in a few seconds.

Other Ways to Bypass Blocks

The Pirate Bay doesn’t even need to bypass the blocks itself. Pirate Bay users have a variety of ways to bypass the block, including accessing The Pirate Bay through proxies or virtual private networks (VPNs), which “tunnel” the traffic to another ISP. From The Pirate Bay’s perspective, the user is accessing their website from another country without website blocking. The tunnel then passes the traffic in encrypted form back to the user – as the traffic is encrypted and the user isn’t communicating directly with The Pirate Bay, their ISP has no way of blocking this traffic.

In fact, The Pirate Party UK hosts a proxy that UK residents can use to access The Pirate Bay on ISPs where it’s been blocked. Tor, designed for accessing websites anonymously and circumventing government censorship of the web, can also be used.

The Streisand Effect

Word spreads about new ISP addresses and other ways to bypass blocks extremely quickly. When a website as big as The Pirate Bay is blocked, news stories spring up and alert users to the block and ways of getting around it. The block may actually increase traffic going to the blocked website as a result of the increased media attention and exposure.

This phenomena is known as the Streisand effect — named after Barbara Streisand, who, in 2003, attempted to remove photos of her house from the Internet. In response, news coverage about the incident resulted in a larger number of people seeing the photos. Similarly, people reading news stories about blocks of a website like The Pirate Bay may wonder what all the fuss is about and check the website out for themselves. News of the block actually increased traffic to The Pirate Bay.

Have you ever had to get around a block to access a blocked website? Do you have any other questions about how websites are blocked? Let us know in the comments!

Image Credit: M2Ys4U on Flickr