China has a network of over 560 million internet users but has been tightly controlled when it comes to internet use in other words, internet censorship. Remarkably, China is ranked among top three most restrictive countries in the world after Iran and Cuba in internet censorship. The fundamental question is how China and countries around the world censor the internet. Apparently, China has devised two criteria of internet censoring: the “Great Firewall” as referred by foreigners whose purpose is to limit the accessibility of foreign websites and the“Golden Shield”a mechanism for local policing. Internet censorship in China commenced by barring a list of non-domestic websites, certain non-local newspapers.
As a matter of fact, internet censorship went a notch higher where a complex technique was used in the Intrusion Detection Systems (IDS) keywords filtering method. As an internet censorship method, it purposely inspected the entire traffic going through much of China’s incoming and outgoing traffic, particularly at the edge routers. When traffic matches with a blacklist of pre-defined keywords, it is muzzled with a TCP connection reset. Incidentally, DNS poisoning is a synonymous internet censorship techniques in China where DNS plus tests which send DNS queries to DNS serves all over the world. Astonishingly, in China Facebook has been blocked since 2009.
Additionally, particular terms on the internet can be censored when queries are raised or instantaneous text messages. Apparently, Google search engine has not been barred entirely: rather internet censorship occurs when the user searches for prohibited keywords are barred for ninety seconds. Subsequently, to show the level on how internet censorship has gone in China, several (internet) service providers are occasionally supplied with copies of prohibited keywords. In China, IP blocking is one of the predominantly technique for internet censorship, where routers are provided a blacklist of inappropriate IP addresses. Thereafter, the router would examine and drop any packet destined to one of the blocked IPs in order for the users not to access connection.
Internet censorship has been cut across countries around the world with countries such as Singapore, Saudi Arabia and Iran devising ways to leverage the design of their network infrastructure to enable filtering possible pulling out countries that have embraces democracy and free speech.
The United States in relation to internet censorship captured domain names and blocked accessibilities to their content owing to allegations of intellectual property infringement. Countries like Iraq closed down internet access for the whole country to avert cheating on national exams. A case in point in Turkey, for instance, internet censorship was applied on Twitter when there emerged some level of allegations in relation to corruption ahead of local elections. The technique applied to censor internet where DNS records were changed in order that any requests for Twitter’s site would be redirected to the state webpage. In Pakistan, internet censorship methods were applied to block the youtube IPs after anti-Islamic videos were aired on youtube. The access-control list (ACLs) was configured on router interfaces to down all packets directing to and from the blacklisted IPs. Again, as a continuous move towards internet censorship, all traffic was deflected to the restricted site to a different location through the creation of a more specific route directing to a null interface, blocking the entire traffic moving to the address.