Following the blocking of Twitter in Turkey, grafitti advertises alternative DNS resolvers as a way to bypass the block.
Should a UK government decide to block Twitter, this advice would be less effective.
It’s not an outlandish suggestion that the UK would do so. In August 2011, during the rioting in London and across the UK, it was reported that the UK government was investigating the capacity to block access to social media sites such as Twitter or Facebook during emergencies.
As of February 2013 this capacity was effectively available, with every major residential broadband provider voluntarily implementing a network-level site blocking plan. These systems utilise either full “Deep Packet Inspection” (used TalkTalk and mobile networks) and DNS interception and manipulation (BT, Sky, Virgin). They inspect your DNS or web traffic regardless of whether you’ve opted-in to parental controls because the same technology is also being used to block sites accused of copyright infringement under Section 97A of the Copyright, Designs and Patents Act.
There are many technical mechanisms that can be used to block access but blocking DNS resolution is usually the easiest.
So, regardless of which DNS server a user selects, a UK government that ordered Twitter blocked could do so, for the bulk of the country, in such a way that merely changing DNS resolvers would not bypass.
These systems have been implemented in the UK without legisaltive mandate, and without clear accountability or independent scrutininy.
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