This is a short overview to circumventing online censorship, but is by no means comprehensive. For a more in-depth guide on how to circumvent online censorship, check out FLOSS Manuals’ guide, Bypassing Censorship.
Many governments, companies, schools, and public access points use software to prevent Internet users from accessing certain websites and Internet services. This is called Internet filtering or blocking and is a form of censorship. Content filtering comes in different forms. Sometimes entire websites are blocked, sometimes individual web pages, and sometimes content is blocked based on keywords contained in it. One country might block Facebook entirely, or only block particular Facebook group pages—or it might block any page or web search with the words “falun gong” in it.
Regardless of how content is filtered or blocked, you can almost always get the information you need by using a circumvention tool. Circumvention tools usually work by diverting your web or other traffic through another computer, so that it bypasses the machines conducting the censorship. An intermediary service through which you channel your communications in this process is called a proxy.
Circumvention tools do not necessarily provide additional security or anonymity, even those that promise privacy or security, even ones that have terms like “anonymizer” in their names.
There are different ways of circumventing Internet censorship, some of which provide additional layers of security. The tool that is most appropriate for you depends on your threat model.
If you’re not sure what your threat model is, start here.
Basic Techniques Anchor link
HTTPS is the secure version of the HTTP protocol used to access websites. Sometimes a censor will block the insecure version of a site only, allowing you to access that site simply by entering the version of the domain that starts with HTTPS. This is particularly useful if the filtering you're experiencing is based on keywords or only blocks individual web pages. HTTPS stops censors from reading your web traffic, so they cannot tell what keywords are being sent, or which individual web page you are visiting (censors can still see the domain names of all websites you visit).
If you suspect this type of simple blocking, try entering https:// before the domain in place of http://.
Try EFF’s HTTPS Everywhere plug-in to automatically turn on HTTPS for those sites that support it.
Another way that you may be able to circumvent basic censorship techniques is by trying an alternate domain name or URL. For example, instead of visiting http://twitter.com, you might visit http://m.twitter.com, the mobile version of the site. Censors that block websites or web pages usually work from a blacklist of banned websites, so anything that is not on that blacklist will get through. They might not know of all the variations of a particular website's domain name—especially if the site knows it is blocked and registers more than one name.
Web-based Proxies Anchor link
A web-based proxy (such as http://proxy.org/) is a good way of circumventing censorship. In order to use a web-based proxy, all you need to do is enter the filtered address that you wish to use; the proxy will then display the requested content.
Web-based proxies a good way to quickly access blocked websites, but often don’t provide any security and will be a poor choice if your threat model includes someone monitoring your internet connection. Additionally, they will not help you to use other blocked non-webpage services such as your instant messaging program. Finally, web-based proxies themselves pose a privacy risk for many users, depending on their threat model, since the proxy will have a complete record of everything you do online.
Encrypted Proxies Anchor link
There are numerous proxy tools that utilize encryption, providing an additional layer of security, as well as the ability to bypass filtering. Although the connection is encrypted, the tool provider may have your personal data, meaning that these tools do not provide anonymity. They are, however, more secure than a plain web-based proxy.
The simplest form of an encrypted web proxy is one that starts with “https”—this will use the encryption usually provided by secure websites. Ironically, in the process, the owners of these proxies will get to see the data you send to and from other secure websites, so be cautious.
Other tools use a hybrid approach—they act like a proxy, but contain elements of the encrypted services listed below. Examples of these tools include Ultrasurf and Psiphon.
Virtual Private Networks Anchor link
A Virtual Private Network (VPN) encrypts and sends all Internet data between your computer and another computer. This computer could belong to a commercial or nonprofit VPN service, your company, or a trusted contact. Once a VPN service is correctly configured, you can use it to access webpages, e-mail, instant messaging, VoIP and any other Internet service. A VPN protects your traffic from being intercepted locally, but your VPN provider can keep logs of your traffic (websites you access, and when you access them) or even provide a third party with the ability to snoop directly on your web browsing. Depending on your threat model, the possibility of a government listening in on your VPN connection or obtaining the logs may be a significant risk and, for some users, could outweigh the short-term benefits of using a VPN.
For information about specific VPN services, click here. Disclaimer: some VPNs with exemplary privacy policies could well be run by devious people. Do not use a VPN that you do not trust.
Tor Anchor link
Tor is free and open-source software that is intended to provide you with anonymity, but which also allows you to circumvent censorship. When you use Tor, the information you transmit is safer because your traffic is bounced around a distributed network of servers, called relays. This could provide anonymity, since the computer with which you’re communicating will never see your IP address, but instead will see the IP address of the last Tor router through which your traffic traveled.
When used with a couple of optional features (bridges and pluggable transports) Tor is the gold standard for secure censorship circumvention against a local state, since it will both bypass almost all national censorship, and if properly configured, protect your identity from an adversary listening in on your country’s networks. It can be slow and hard to use, however.
To learn how to use Tor, click here