The Great Firewall of China (GFW) is the combination of legislative actions and technologies enforced by the People’s Republic of China to regulate the Internet domestically. Its role in the Internet censorship in China is to block access to selected foreign websites and to slow down cross-border internet traffic. The effect includes: limiting access to foreign information sources, blocking foreign internet tools (e.g. Google search, Facebook, Twitter, Wikipedia, and others) and mobile apps, and requiring foreign companies to adapt to domestic regulations. Besides censorship, the GFW has also influenced the development of China’s internal internet economy by nurturing domestic companies and reducing the effectiveness of products from foreign internet companies.
The Great Firewall is operated under the “Golden Shield Project” by the Bureau of Public Information and Network Security Supervision (traditional Chinese: 公共信息網絡安全監察局; simplified Chinese: 公共信息网络安全监察局; pinyin: Gōnggòng xìnxī wǎngluò ānquán jiānchá jú) or (Chinese: 网监局; pinyin: wǎng jiān jú) for short).
As mentioned in the “One country, two systems” principle, China’s special administrative regions such as Hong Kong and Macau are not affected by the project, as SARs have their own governmental and legal systems and therefore enjoy a high degree of autonomy. Nevertheless, the U.S. State Department has reported that the central government authorities have closely monitored Internet use in these regions.
The term Great Firewall of China is a portmanteau of firewall and the Great Wall of China, was first used in print by Geremie Barmé in 1997. The term started its use in Beijing in 1996 by Stephen Guerin of Redfish Group, a Beijing-based web consultancy. 1996 interviews of Guerin by CNN’s Andrea Koppel and NPR’s Marky Kay Magistad included Guerin discussing China’s “reversing the firewall”.
The political and ideological background of the GFW Project is considered to be one of Deng Xiaoping’s favorite sayings in the early 1980s: “If you open the window, both fresh air and flies will be blown in.” (Chinese: 打开窗户，新鲜空气和苍蝇就会一起进来。; pinyin: Dǎkāi chuānghù, xīnxiān kōngqì hé cāngying jiù huì yìqǐ jìnlái.) The saying is related to a period of the economic reform of China that became known as the “socialist market economy”. Superseding the political ideologies of the Cultural Revolution, the reform led China towards a market economy and opened up the market for foreign investors. Nonetheless, despite the economic freedom, values and political ideas of the Communist Party of China have had to be protected by “swatting flies” of other unwanted ideologies.
The Internet in China arrived in 1994, as the inevitable consequence of and supporting tool for the “socialist market economy”. Gradually, while Internet availability has been increasing, the Internet has become a common communication platform and tool for trading information.
The Ministry of Public Security took initial steps to control Internet use in 1997, when it issued comprehensive regulations governing its use. The key sections, Articles 4–6, are:
Individuals are prohibited from using the Internet to: harm national security; disclose state secrets; or injure the interests of the state or society. Users are prohibited from using the Internet to create, replicate, retrieve, or transmit information that incites resistance to the PRC Constitution, laws, or administrative regulations; promoting the overthrow of the government or socialist system; undermining national unification; distorting the truth, spreading rumors, or destroying social order; or providing sexually suggestive material or encouraging gambling, violence, or murder. Users are prohibited from engaging in activities that harm the security of computer information networks and from using networks or changing network resources without prior approval.
In 1998, the Communist Party of China feared that the China Democracy Party (CDP) would breed a powerful new network that the party elites might not be able to control. The CDP was immediately banned, followed by arrests and imprisonment. That same year, the GFW project was started. The first part of the project lasted eight years and was completed in 2006. The second part began in 2006 and ended in 2008. On 6 December 2002, 300 people in charge of the GFW project from 31 provinces and cities throughout China participated in a four-day inaugural “Comprehensive Exhibition on Chinese Information System”. At the exhibition, many western high-tech products, including Internet security, video monitoring and human face recognition were purchased. It is estimated that around 30,000–50,000 police were employed in this gigantic project.
Origins of Chinese Internet law
China’s view of the internet is as “Internet sovereignty”: the notion that the Internet inside the country is part of the country’s sovereignty and should be governed by the country.
While the United States and several other western countries passed laws creating computer crimes beginning in the 1970s, China had no such legislation until 1997. That year, China’s sole legislative body, the National People’s Congress (NPC) passed CL97, a law that criminalizes “cyber crimes” , which it divided into two broad categories: crimes that target computer networks and crimes carried out over computer networks. Behavior illegal under the latter category includes among many things the dissemination of pornographic material and the usurping of “state secrets.”
Some Chinese judges were critical of CL97, calling it ineffective and unenforceable. However, the NPC claimed it intentionally left the law “flexible” so that it could be open to future interpretation and development. Given the gaps in the law, the central government of China relies heavily on its administrative body, the State Council, to determine what falls under the definitions, and their determinations are not required to go through the NPC legislative process. As a result, the CPC has ended up relying heavily on state regulation to carry out CL97.
The latter definition of online activities punishable under CL97, or “crimes carried out over computer networks” is used as justification for the Great Firewall and can be cited when the government blocks any ISP, gateway connections, or any access to anything on the internet. The definition also includes using the internet to distribute information considered “harmful to national security,” and using the internet to distribute information considered “harmful to public order, social stability, and Chinese morality.” The central government relies heavily on its State Council regulators to determine what specific online behavior and speech fall under these definitions.
The reasons behind the Internet censorship in China include:
- Social Control: The Internet is a means for freedom of speech, and dissemination of campaigns could lead to protests against the government.
- Sensitive Content: To control information about the government in China.
- Economic Protectionism: China prefers the use of local companies that are regulated by Chinese regulations, since they have more power over them. E.g. Baidu over Google.
Campaigns and crackdowns
As part of the Great Firewall, beginning in 2003 China started the Golden Shield Project , a massive surveillance and censoring system, the hardware for which was provided by mostly U.S. companies, including Cisco Systems. The project was completed in 2006 and is now carried out in buildings with machines manned by civilians and supervised by China’s national police force, the Public Security Bureau (PSB). The main operating activities of the gatekeepers at the Golden Shield Project include monitoring domestic websites and email and searching for politically sensitive language and calls to protest. When damaging content is found, local PSB officials can be dispatched to investigate or make arrests. However, by late 2007 the Golden Shield Project proved to operate sporadically at best, as users had long adapted to internet blocking by using proxy servers, among other strategies, to make communications and circumnavigate to blocked content.
In February 2008, the Chinese government announced “Operation Tomorrow,” an effort to crack down on youth usage of internet cafés to play online games and view content declared illegal. Internet cafés, an extremely popular way of getting online in developing countries where fewer people can afford a personal computer, are regulated by the Chinese government and by local Chinese government officials. Minors (in China, those under the age of 18) are not allowed into Internet cafés, although this law is widely ignored and when enforced, has spurred the creation of underground “Black Web Bars” visited by those underage. As of 2008 internet cafés were required to register every customer in a log when they used the internet there; these records may be confiscated by local government officials and the PSB. To illustrate local regulation of internet cafés, in one instance, a government official in the town of Gedong lawfully banned internet cafés from operating in the town because he believed them to be harmful to minors, who frequented them to play online games (including those considered violent) and surf the internet. However, internet cafés in this town simply went underground and most minors were not deterred from visiting them.
In May 2015, China indefinitely blocked access to the Chinese-language Wikipedia. In contrast (as of 2018), the English-language Wikipedia is blocked only rarely and intermittently. China in 2017 discussed plans for its own version of Wikipedia. As of May 2019, all language versions of Wikipedia have been blocked by the Chinese government.
The system blocks content by preventing IP addresses from being routed through. It consists of standard firewalls and proxy servers at the Internet gateways. The system also selectively engages in DNS poisoning when particular sites are requested. The government does not appear to be systematically examining Internet content, as this seems to be technically impractical. Researchers at the University of California, Davis, and at the University of New Mexico said that the censorship system is not a true firewall since banned material is sometimes able to pass through several routers or through the entire system without being blocked. Details for some commonly used technical methods for censoring are:
|IP range ban using Black holes||The Chinese firewall maintains a list of IP ranges that are automatically dropped (network black-holing).The network location of routers effectively performing the drop seems to vary between Chinese internet providers, but the general consensus is that packets are dropped when crossing an MPLS node, which are intensively used in the Chinese backbone internet. This would suggest that the list of dropped networks is likely maintained using LDP. |
Network ranges in this list include Facebook ,Twitter and Dropbox ASN.
Because of the complexity to maintain a big, up-to-date banned network list, and because this method has proven to not be compatible with services using Content delivery networks, it is usually used as last resort and other blocking methods are preferred (such as filtering based on QoS).
|DNS spoofing, filtering and redirection||One part of the Chinese firewall is made of liar DNS servers and DNS hijackers returning incorrect IP addresses. Studies seems to point out that this censorship is keyword-based. Censors are likely maintaining two lists : a list of banned domain names, and a list of whitelisted domain names. Both list could possibly use “” matching one or multiple characters. Examples of banned websites include “*greatfire.org” or “*falungong*”, examples of whitelisted websites include “developer.android.google.cn”.The list of banned/allowed keyword seems to be shared between multiple Chinese Internet providers, suggesting central management. |
Contrary to a general belief, foreign DNS resolvers (such as Google Public DNS / 126.96.36.199) are reported to work correctly inside the country. However, these DNS servers are also subject to hijacking : Any DNS query will reach the DNS server, but if the request matches a banned keyword, the firewall will inject a fake DNS reply with goal to provide an incorrect reply before the legitimate DNS server.
Since 2015, IP addresses returned for blocked domains are random IPs within the range of a black-holed network.
Typical circumvention methods include modifying the Hosts file, typing the IP address instead of the domain name in a Web browser or using DNS over TLS/HTTPS.
|URLfiltering using transparent proxies||The Chinese firewall is made of transparent proxies filtering web traffic. These proxies scan the requested URI, the “Host” Header and the content of the web page (for HTTP requests) or the Server Name Indication (for HTTPS requests) for target keywords. If the firewall believe that the page should be blocked, a 403 error page may displayed instead, or the page may not load at all.Studies have found multiple limitations to these proxies, such as the inability to inspect POST data in HTTP requests, to filter malformed HTTP requests, or to inspect new protocols like webSocket. |
Like for DNS filtering, this method is keyword based. The list of banned keyword is not the same however : As of 2019, wikipedia.org is blocked in China using transparent proxies only. Encrypting the Server Name Indication can also be used to bypass this method of filtering and is currently in development by the IETF.
|Quality of servicefiltering||Since 2012, the GFW is able to “learn, filter and block” users based on traffic behavior, using Machine learning. This method was originally developed for blocking VPN and has been extended to become part of the standard filtering system of the GFW.This method works by mirroring all traffic (using a network tap) to a dedicated analytics unit, that will then deliver a score for each destination IP based on how suspicious the connection is. This score will be used later as Packet loss rate by routers of the Chinese firewall, resulting in an slowness in the connection. |
This method aims to slows down traffic extremely, making it exceed timeout on the client side, thus effectively blocking the service.
It is believed that the analytics system is using Side-channel (such as the size of packets) to estimate how suspicious is a connection. It is able to detect traffic patterns (such as SSH tunneling, VPN or Tor protocols), and can measure packets Entropy to detect encrypted-over-encrypted traffic (such as HTTPS over an SSL tunnel).
This system does not require human interaction to work, and is completely separated from DNS filtering and proxies systems.
|Packet forging and TCP reset attacks||The Chinese firewall may arbitrary terminate TCP transmissions, using packet forging. The blocking is performed using a TCP reset attack. This attack does not block TCP requests nor TCP replies, but send a malicious TCP RST packet to the sender, simulating an end-of-connection.Side channel analysis seems to indicate that TCP Reset are coming from an infrastructure collocated or shared with QoS filtering routers. This infrastructure seems to update the scoring system : if a previous TCP connection is blocked by the filter, future connection attempts from both sides may also be blocked for short period of times (up to few hours). |
An efficient circumvention method is to ignore the reset packet sent by the firewall a patch for FreeBSD has been developed for this purpose.
|Man-in-the-middle attackswith TLS||The Chinese Cyber Security Law theoretically allows the Chinese government to request and use the root certificate from any Chinese certificate authority, such as CNNIC, to make MITM attacks. Multiple incidents also happened in the last decade, before the creation of the law: |
On 26 Jan 2013, the GitHub SSL certificate was replaced with a self-signed certificate in China by he GFW.On 20 Oct 2014, iCloud SSL certificate was replaced with a self-signed certificate in China. It is believed that the Chinese government discovered a vulnerability on Apple devices and was exploiting itOn 20 Mar 2015, Google detected valid certificates for Google signed by CNNIC in Egypt. In response of this event, and after a deeper investigation, CNNIC certificate has been removed by some browsers. Because of the removal being based on proofs and not suspicion, no other Chinese certificate authority has been removed from web browsers, and some have been added since then.
This type of attack can be circumvented by websites implementing Certificate Transparency.
Other reported methods have included:
|Network enumeration||It has been reported that unknown entities within China, likely with deep packet inspection (DPI) capabilities, have initiated unsolicited TCP/IP connections to computers within the United States for the purported purpose of network enumeration of services, in particular TLS/SSL and Tor (anonymity network) services, with the aim of facilitating IP blocking.|
Effectiveness and Impact
Some research evidence has indicated that suspicion of the Great Firewall in China and the sense that one is being surveilled online leads to chilled speech and self-censorship, which has been more effective at blocking internet content than the Great Firewall has been.
The Great Firewall is a form of trade protectionism that has allowed China to grow its own internet giants: Tencent, Alibaba, and Baidu. China has its own version of many foreign web properties, for example: Tencent Video (YouTube), Tencent Weibo (Twitter), Qzone (Facebook), WeChat (WhatsApp), Ctrip (Orbitz and others), Zhihu (Quora). With nearly one quarter of the global internet population (700 million users), the internet behind the GFW can be considered a “parallel universe” to the Internet that exists outside.
Mainland Chinese Internet censorship programs have censored Web sites that include (among other things):
- Web sites belonging to “outlawed” or suppressed groups, such as pro-democracy activists and Falun Gong.
- News sources that often cover topics that are considered defamatory against China, such as police brutality, Tiananmen Square protests of 1989, freedom of speech, democracysites. These sites include Voice of America and the Chinese edition of BBC News.
- Sites related to the Taiwanese government, media, or other organizations, including sites dedicated to religious content, and most large Taiwanese community websites or blogs.
- Web sites that contain anything the Chinese authorities regard as obscenity or pornography.
- Web sites relating to criminal activity.
- Sites linked with the Dalai Lama, his teachings or the International Tibet Independence Movement.
- Most blogging sites experience frequent or permanent outages.
- Web sites deemed as subversive.
Blocked Web sites are indexed to a lesser degree, if at all, by some Chinese search engines. This sometimes has considerable impact on search results.
According to The New York Times, Google has set up computer systems inside China that try to access Web sites outside the country. If a site is inaccessible, then it is added to Google China’s blacklist. However, once unblocked, the Web sites will be reindexed. Referring to Google’s first-hand experience of the great firewall, there is some hope in the international community that it will reveal some of its secrets. Simon Davies, founder of London-based pressure group Privacy International, is now challenging Google to reveal the technology it once used at China’s behest. “That way, we can understand the nature of the beast and, perhaps, develop circumvention measures so there can be an opening up of communications.” “That would be a dossier of extraordinary importance to human rights,” Davies says. Google has yet to respond to his call.
Because the Great Firewall blocks destination IP addresses and domain names and inspects the data being sent or received, a basic censorship circumvention strategy is to use proxy nodes and encrypt the data. Most circumvention tools combine these two mechanisms.
- Proxy servers outside China can be used, although using just a simple open proxy (HTTP or SOCKS) without also using an encrypted tunnel (such as HTTPS) does little to circumvent the sophisticated censors.
- Companies can establish regional Web sites within China. This prevents their content from going through the Great Firewall of China; however, it requires companies to apply for local ICP licenses.
- Onion routing and Garlic routing, such as I2P or Tor, can be used.
- Freegate, Ultrasurf, and Psiphon are free programs that circumvent the China firewall using multiple open proxies, but still behave as though the user is in China.
- VPNs (virtual private network) and SSH (secure shell) are the powerful and stable tools for bypassing surveillance technologies. They use the same basic approaches, proxies and encrypted channels, used by other circumvention tools, but depend on a private host, a virtual host, or an account outside of China, rather than open, free proxies.
- Open application programming interface (API) used by Twitter which enables to post and retrieve tweets on sites other than Twitter. “The idea is that coders elsewhere get to Twitter, and offer up feeds at their own URLs—which the government has to chase down one by one.” says Jonathan Zittrain, co-director of Harvard’s Berkman Center for Internet and Society.
- Reconfiguration at the end points of communication, encryption, discarding reset packets according to the TTL value (time to live) by distinguishing those resets generated by the Firewall and those made by end user, not routing any further packets to sites that have triggered blocking behavior.
In 2008 the English-language BBC website (but not the Chinese language website) was unblocked.
In 2017 China censored Google, including Google Maps. Alternate map applications are available.
Reporters Without Borders suspects that countries such as Cuba, Vietnam, Zimbabwe and Belarus have obtained surveillance technology from China, although the censorship in these countries is less stringent than in China.
Even so, one can see the booming sector as well as one of the most dynamic. China is the second largest information and communication technology market, according to the International Data Corporation this market should reach US$844 billion by 2020. The market for big data is expected to become part of the industrial world of China by 2025. Regardless of the strictness the industrial internet architecture is already in place.
Protest in China
Despite strict government regulations, the Chinese people continue to protest against their government’s attempt to censor the Internet. The more covert protesters set up secure SSH and VPN connections using tools such as UltraSurf. They can also utilize the widely available proxies and virtual private networks to fanqiang (翻墙, “climb over the wall”), or bypass the GFW. Active protest is not absent. Chinese people post their grievances online, and on some occasions, have been successful. In 2003, the death of Sun Zhigang, a young migrant worker, sparked an intense, widespread online response from the Chinese public, despite the risk of the government’s punishment. A few months later, Premier Wen Jiabao abolished the Chinese law that led to the death of Sun. Ever since, dissent has regularly created turmoil on the Internet in China. Also in January 2010, when Google announced that it will no longer censor its Web search results in China, even if this means it might have to shut down its Chinese operations altogether, many Chinese people went to the company’s Chinese offices to display their grievances and offer gifts, such as flowers, fruits and cigarettes.
Chinese corporate statutes mandate that domestic and foreign internet companies doing business in Mainland China cooperate with its Great Firewall efforts. Companies are responsible for the content that they put on their websites as well as the content that users post on their website. This helps China promote self-censorship, making their censoring job less difficult, and allowing them to keep being a state that licenses all their media.
The Chinese subsidiaries of American companies Yahoo!, Google, (Google services are blocked but Google still has a presence in China) and Microsoft comply with this condition of operating there. While the leadership of these companies regularly express their distaste for China’s Great Firewall policies, in the same vein they consider it a necessary part of doing business in China and better than the alternative, which would be to not have any China business at all. Jerry Yang, a founder of Yahoo!, additionally has implied that the presence of foreign internet companies in China will eventually help bring about less internet restriction in China.
Arguments against the GFW
Critics argue that the GFW is a consequence of China’s paranoia of the potential that the Internet has of spreading opposition to their one-party rule. Other arguments given against China are that their method of having a limited Internet impedes freedom of speech and that it holds them down, economically speaking, by discouraging innovation, disapproving communication of important ideas and prohibiting firms the use of certain services that they use. It is also thought to be a detrimental approach for students and professors since they do not have access to resources which promote the sharing of work and ideas for a more comprehensive learning.
Another important argument against the GFW and fear that the critics have is that if other big countries begin following China’s approach, the whole purpose of the creation of the Internet could be put in jeopardy. If like-minded countries are successful in imposing the same restrictions on their inhabitants and globalized online companies, then the free global exchange of information could cease to exist.
Reaction of the United States
The United States Trade Representative’s (USTR) “ National Trade Estimate Report ” in 2016 referred the China’s digital Great Firewall: “China’s filtering of cross-border Internet traffic has posed a significant burden to foreign suppliers.” Claude Barfield, the American Enterprise Institute’s expert of International trade, suggested that the U.S. government should bring a case against the Firewall, a huge trade barrier, in the World Trade Organization in January 2017. 8 of the 24 more trafficked websites in China have been blocked by The Great Firewall. This has created a burden to foreign suppliers who rely on these websites to sell their products or services.The lobby’s 2016 business climate survey showed 79 percent of its members reported a negative impact on business due to internet censorship.
According to Stephen Rosen, the GFW is reflective of the Chinese government’s fear of civil disobedience or rebellion among the Chinese population against the Chinese Communist Party’s rule:
If you want to know what people are worried about look at what they spend their money on. If you’re afraid of burglars you buy a burglar alarm. What are the Chinese spending their money on? We’re told from Chinese figures they’re spending on the People’s Armed Police, the internal security force is about as big as they’re spending on the regular military. This whole great firewall of Chinese, this whole massive effort to control the internet, this effort to use modern information technology not to disseminate information, empowering individuals, but to make people think what you want them to think and to monitor their behavior so that you can isolate and suppress them. That’s because this is a regime which is fundamentally afraid of its own people. And it’s fundamentally hostile to them.
- There are several variants of this saying in Chinese, including “如果你打开窗户换新鲜空气，就得想到苍蝇也会飞进来。” and “打开窗户，新鲜空气进来了，苍蝇也飞进来了。”. Their meanings are the same.
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