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{{Short description|Chinese internet regulations}}
{{Use dmy dates|date=November 2023}}{{Politics of China|expanded=Publicity}}
The '''Great Firewall''' ('''GFW'''; {{zh|s=防火长城|t=防火長城|p=Fánghuǒ Chángchéng}}) is the combination of legislative actions and technologies enforced by the [[China|People's Republic of China]] to regulate the [[Internet]] domestically.<ref>{{Cite journal |last1=Clayton |first1=Richard |last2=Murdoch |first2=Steven J. |last3=Watson |first3=Robert N. M. |title=Ignoring the great firewall of china |journal=International Workshop on Privacy Enhancing Technologies}}</ref> Its role in [[internet censorship in China]] is to block access to selected foreign websites and to slow down cross-border internet traffic.<ref>{{cite news|last1=Mozur|first1=Paul|title=Baidu and CloudFlare Boost Users Over China's Great Firewall|url=https://www.nytimes.com/2015/09/14/business/partnership-boosts-users-over-chinas-great-firewall.html|work=[[The New York Times]]|date=13 September 2015|language=en|access-date=16 September 2017|archive-url=https://web.archive.org/web/20190124123846/https://www.nytimes.com/2015/09/14/business/partnership-boosts-users-over-chinas-great-firewall.html|archive-date=24 January 2019|url-status=live}}</ref> The Great Firewall operates by checking [[transmission control protocol]] (TCP) packets for keywords or sensitive words. If the keywords or sensitive words appear in the TCP packets, access will be closed. If one link is closed, more links from the same machine will be blocked by the Great Firewall.<ref>{{Cite book |last1=Clayton |first1=Richard |last2=Murdoch |first2=Steven J. |last3=Watson |first3=Robert N. M. |date=2006 |editor-last=Danezis |editor-first=George |editor2-last=Golle |editor2-first=Philippe |chapter=Ignoring the Great Firewall of China |chapter-url=https://link.springer.com/chapter/10.1007/11957454_2 |title=Privacy Enhancing Technologies |series=Lecture Notes in Computer Science |volume=4258 |language=en |location=Berlin, Heidelberg |publisher=Springer |pages=20–35 |doi=10.1007/11957454_2 |isbn=978-3-540-68793-1|hdl=1811/72793 |hdl-access=free }}</ref> The effect includes: limiting access to foreign information sources, blocking popular foreign websites (e.g. [[Google Search]],<ref>{{cite web|url=https://en.greatfire.org/google.com|title=google.com is blocked in China {{!}} GreatFire Analyzer|website=en.greatfire.org|url-status=live|archive-url=https://web.archive.org/web/20140805232352/https://en.greatfire.org/google.com|archive-date=2014-08-05|access-date=2020-01-18}}</ref> [[Facebook]],<ref>{{cite web |title=How China's social media users created a new language to beat censorship on COVID-19 |url=https://www.amnesty.org/en/latest/news/2020/03/china-social-media-language-government-censorship-covid/ |website=[[Amnesty International]] |access-date=3 April 2020 |language=en |date=6 March 2020 |archive-url=https://web.archive.org/web/20200403023740/https://www.amnesty.org/en/latest/news/2020/03/china-social-media-language-government-censorship-covid/ |archive-date=3 April 2020 |url-status=live }}</ref> [[Twitter]],<ref>{{cite news|url=https://www.washingtonpost.com/wp-dyn/content/article/2009/07/07/AR2009070701162.html|title=China Blocks Access To Twitter, Facebook After Riots|newspaper=Washington Post|url-status=live|archive-url=https://web.archive.org/web/20100919204716/http://www.washingtonpost.com/wp-dyn/content/article/2009/07/07/AR2009070701162.html|archive-date=19 September 2010|access-date=18 January 2020}}</ref> [[Wikipedia]],<ref>{{cite web|url=https://www.theverge.com/2015/9/4/9260981/jimmy-wales-wikipedia-china|title=Wikipedia founder defends decision to encrypt the site in China|date=4 September 2015|publisher=[[The Verge]]|access-date=17 April 2018|archive-url=https://web.archive.org/web/20180612141751/https://www.theverge.com/2015/9/4/9260981/jimmy-wales-wikipedia-china|archive-date=12 June 2018|url-status=live}}</ref><ref>{{Cite news|url=https://www.ibtimes.co.uk/chinas-government-has-blocked-wikipedia-its-entirety-again-1532138|title=China's government has blocked Wikipedia in its entirety again|last=Skipper|first=Ben|date=7 December 2015|work=[[International Business Times]] UK|access-date=2 May 2018|archive-url=https://web.archive.org/web/20180503111142/https://www.ibtimes.co.uk/chinas-government-has-blocked-wikipedia-its-entirety-again-1532138|archive-date=3 May 2018|url-status=live}}</ref> and others) and mobile apps, and requiring foreign companies to adapt to domestic regulations.<ref>{{cite news|last1=Mozur|first1=Paul|last2=Goel|first2=Vindu|title=To Reach China, LinkedIn Plays by Local Rules|url=https://www.nytimes.com/2014/10/06/technology/to-reach-china-linkedin-plays-by-local-rules.html?mcubz=0|work=The New York Times|date=5 October 2014|access-date=4 September 2017|archive-url=https://web.archive.org/web/20180613111912/https://www.nytimes.com/2014/10/06/technology/to-reach-china-linkedin-plays-by-local-rules.html?mcubz=0|archive-date=13 June 2018|url-status=live}}</ref><ref>{{cite news|last1=Branigan|first1=Tania|title=New York Times launches website in Chinese language|url=https://www.theguardian.com/media/2012/jun/28/new-york-times-launches-chinese-website|work=[[The Guardian]]|date=28 June 2012|access-date=4 September 2017|archive-url=https://web.archive.org/web/20170904154029/https://www.theguardian.com/media/2012/jun/28/new-york-times-launches-chinese-website|archive-date=4 September 2017|url-status=live}}</ref>

Besides censorship, the Great Firewall has also influenced the development of China's internal internet economy by giving preference to domestic companies<ref name="washingtonpost.com">{{cite news|last1=Denyer|first1=Simon|title=China's scary lesson to the world: Censoring the Internet works|url=https://www.washingtonpost.com/world/asia_pacific/chinas-scary-lesson-to-the-world-censoring-the-internet-works/2016/05/23/413afe78-fff3-11e5-8bb1-f124a43f84dc_story.html|newspaper=[[The Washington Post]]|access-date=5 September 2017|date=23 May 2016|archive-url=https://web.archive.org/web/20181206113628/https://www.washingtonpost.com/world/asia_pacific/chinas-scary-lesson-to-the-world-censoring-the-internet-works/2016/05/23/413afe78-fff3-11e5-8bb1-f124a43f84dc_story.html|archive-date=6 December 2018|url-status=live}}</ref> and reducing the effectiveness of products from foreign internet companies.<ref name="WaPo2017">{{cite news|last1=Rauhala|first1=Emily|date=19 July 2016|title=America wants to believe China can't innovate. Tech tells a different story.|url=https://www.washingtonpost.com/world/asia_pacific/america-wants-to-believe-china-cant-innovate-tech-tells-a-different-story/2016/07/19/c17cbea9-6ee6-479c-81fa-54051df598c5_story.html|url-status=live|archive-url=https://web.archive.org/web/20170903210759/https://www.washingtonpost.com/world/asia_pacific/america-wants-to-believe-china-cant-innovate-tech-tells-a-different-story/2016/07/19/c17cbea9-6ee6-479c-81fa-54051df598c5_story.html|archive-date=3 September 2017|access-date=5 September 2017|newspaper=The Washington Post}}</ref> The techniques deployed by the Chinese government to maintain control of the Great Firewall can include modifying search results for terms, such as they did following [[Ai Weiwei]]’s arrest, and petitioning global conglomerates to remove content, as happened when they petitioned [[Apple Inc.|Apple]] to remove the [[Quartz (publication)|''Quartz'']] business news publication’s app from its Chinese App Store after reporting on the [[2019–2020 Hong Kong protests]].<ref>{{cite web|url=https://9to5mac.com/2019/10/09/apple-china-quartz-app-store/|title=Apple removes 'Quartz' news app from Chinese App Store|last=Miller|first=Chance|date=2019-10-09|website=9to5Mac|language=en-US|access-date=2019-10-10|archive-url=https://web.archive.org/web/20191010065316/https://9to5mac.com/2019/10/09/apple-china-quartz-app-store/|archive-date=2019-10-10|url-status=live}}</ref><ref>{{cite web|url=https://www.theverge.com/2019/10/9/20907228/apple-quartz-app-store-china-removal-hong-kong-protests-censorship|title=Apple removes Quartz news app from the Chinese App Store over Hong Kong coverage|last=Statt|first=Nick|date=2019-10-09|website=The Verge|language=en|access-date=2019-10-10|archive-url=https://web.archive.org/web/20191010015646/https://www.theverge.com/2019/10/9/20907228/apple-quartz-app-store-china-removal-hong-kong-protests-censorship|archive-date=2019-10-10|url-status=live}}</ref>

The Great Firewall was formerly operated by the [[State Internet Information Office|SIIO]], as part of the [[Golden Shield Project]]. Since 2013, the firewall is technically operated by the [[Cyberspace Administration of China]] (CAC), which is the entity in charge of translating the [[Chinese Communist Party]]'s [[Ideology of the Chinese Communist Party|ideology]] and policy into technical specifications.

As mentioned in the "[[one country, two systems]]" principle, China's [[Special administrative regions of China|special administrative regions]] (SARs) such as [[Hong Kong]] and [[Macau]] are not affected by the firewall, as SARs have their own governmental and legal systems and therefore enjoy a higher degree of autonomy. Nevertheless, the [[U.S. State Department]] has reported that the central government authorities have closely monitored Internet use in these regions,<ref>{{Cite news|url=https://2009-2017.state.gov/j/drl/rls/hrrpt/2011/eap/187483.htm|title=China (includes Tibet, Hong Kong, and Macau) - Hong Kong|work=[[U.S. Department of State]]|access-date=29 July 2018|language=en-US|archive-url=https://web.archive.org/web/20190701191914/https://2009-2017.state.gov/j/drl/rls/hrrpt/2011/eap/187483.htm|archive-date=1 July 2019|url-status=live}}</ref> and Hong Kong's [[2020 Hong Kong national security law|National Security Law]] has been used to block websites documenting [[List of protests in Hong Kong|anti-government protests]].<ref>{{cite web |title=Hong Kong police use national security law for first time to block access to website recording anti-government protests, officers' details |url=https://www.scmp.com/news/hong-kong/law-and-crime/article/3117072/hong-kong-police-use-national-security-law-block |website=South China Morning Post |date=9 January 2021 |access-date=13 January 2021 |archive-date=28 April 2021 |archive-url=https://web.archive.org/web/20210428165219/https://www.scmp.com/news/hong-kong/law-and-crime/article/3117072/hong-kong-police-use-national-security-law-block |url-status=live }}</ref>

Provincial governments in parts of China, such as [[Henan|Henan Province]], run their own versions of the firewall.<ref>{{Cite web |date=2025-05-11 |title=A Wall Behind A Wall: Emerging Regional Censorship in China |url=https://gfw.report/publications/sp25/en/ |access-date=2025-05-23 |website=GFW Report |language=en}}</ref><ref>{{Cite web |last=Kaufman |first=Arthur |date=2025-05-20 |title=Henan Develops Its Own Regional Great Firewall, Adding Layers to China's Censorship |url=https://chinadigitaltimes.net/2025/05/henan-develops-its-own-regional-great-firewall-adding-layers-to-chinas-censorship/ |access-date=2025-05-23 |website=[[China Digital Times]] |language=en-US}}</ref><ref>{{Cite news |last=Hawkins |first=Amy |date=2025-05-24 |title=‘Alarming’ rise in regional internet censorship in China, study finds |url=https://www.theguardian.com/world/2025/may/24/alarming-rise-in-regional-internet-censorship-in-china-study-finds |access-date=2025-05-24 |work=[[The Guardian]] |language=en-GB |issn=0261-3077}}</ref>

The term ''Great Firewall of China'' is a combination of the word [[Firewall (computing)|firewall]] with the [[Great Wall of China]]. The phrase "Great Firewall of China" was first used in print by Australian [[sinologist]] [[Geremie Barmé]] in 1997.<ref>{{cite news|last1=Lanfranco|first1=Edward|title=The China Yahoo! welcome: You've got Jail!|url=http://www.upi.com/The-China-Yahoo-welcome-Youve-got-Jail/40351126286824/|work=UPI|date=9 September 2005|language=en|access-date=9 August 2017|archive-url=https://web.archive.org/web/20170810052910/http://www.upi.com/The-China-Yahoo-welcome-Youve-got-Jail/40351126286824/|archive-date=10 August 2017|url-status=live}}</ref><ref>{{Cite journal |url=https://www.wired.com/1997/06/china-3/ |title=The Great Firewall of China |journal=[[Wired (website)|Wired]] |last1=Barme |first1=Geremie R. |last2=Ye |first2=Sang |date=6 January 1997 |access-date=29 December 2015 |archive-url=https://web.archive.org/web/20160101024548/http://www.wired.com/1997/06/china-3/ |archive-date=2016-01-01|url-status=live }}</ref>

==History==
A favorite saying of [[Deng Xiaoping]]'s in the early 1980s, "If you open the window, both fresh air and flies will be blown in", is considered to be the political and ideological basis of the GFW Project.<ref group=nb>{{zh|c=打开窗户，新鲜空气和苍蝇就会一起进来。|p= Dǎkāi chuānghù, xīnxiān kōngqì hé cāngying jiù huì yìqǐ jìnlái|scase=yes}}.<br />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.</ref> 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 Chinese Communist Party (CCP) have had to be protected by "swatting flies" of other unwanted ideologies.<ref>R. MacKinnon "Flatter world and thicker walls? Blogs, censorship and civic discourse in China" ''[[Public Choice (journal)|Public Choice]]'' (2008) 134: p. 31–46, Springer</ref>

The [[internet in China]] arrived in 1994,<ref>{{cite web |url=http://www.chinanews.com/special/guoqing/60/2009/06-25/122.shtml |title=中国接入互联网 |publisher=[[China News Service]] |access-date=28 August 2013 |archive-url=https://web.archive.org/web/20140219141011/http://www.chinanews.com/special/guoqing/60/2009/06-25/122.shtml |archive-date=19 February 2014 |url-status=live }}</ref> as the inevitable consequence of and supporting tool for a "socialist market economy". Gradually, while Internet availability has been increasing, the Internet has become a common communication platform and tool for trading information.

The Chinese government's control over the Internet began in 1996 when Premier [[Li Peng]] signed State Council Order No. 195, issuing the "Interim Regulations on the Management of International Networking of Computer Information Networks". Article 6 of the Regulations states: "Computer information networks that directly connect to the international network must use the international entry and exit channels provided by the Ministry of Posts and Telecommunications’ national public telecommunications network. No unit or individual may establish or use other channels to connect to the international network on their own." This regulation was later widely used to punish "climbing over the firewall".<ref name="solidot0924">{{cite news |author=Edwards |date=2023-09-24 |title=网友称为境外公司远程工作被没收所有违法所得 |url=https://www.solidot.org/story?sid=76177 |url-status=live |archive-url=https://web.archive.org/web/20240105030111/https://www.solidot.org/story?sid=76177 |archive-date=2024-01-05 |access-date=2024-01-15 |work=[[Solidot]]}}</ref>

The [[Ministry of Public Security (China)|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:
{{blockquote|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.<ref>"China and the Internet.", ''[[International Debates]]'', 15420345, Apr2010, Vol. 8, Issue 4</ref>}}

In 1998, the Chinese Communist Party feared that the [[China Democracy Party]] (CDP) would breed a powerful new network that CCP elites might not be able to control.<ref>Goldman, Merle Goldman. Gu, Edward X. [2004] (2004). Chinese Intellectuals between State and Market. [[Routledge]]. {{ISBN|0415325978}}</ref> The CDP was immediately banned, followed by arrests and imprisonment.<ref>{{cite book |last1=Goldsmith |first1=Jack L. |author-link1=Jack Goldsmith |last2=Wu |first2=Tim |author-link2=Tim Wu |title=Who Controls the Internet?: Illusions of a Borderless World |publisher=[[Oxford University Press]] |year=2006 |location=New York |isbn=0-19-515266-2 |page=[https://archive.org/details/whocontrolsinter00gold/page/91 91] |title-link=Who Controls the Internet? }}</ref> 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 [[Province (China)|provinces]] and [[List of cities in China|cities]] throughout China participated in a four-day inaugural "Comprehensive Exhibition on Chinese Information System".<ref>{{cite web|url=https://www.adsale.com.hk/corporate/idx/eng/adsale_group|title=Adsale Corporate Website - Adsale Group|first=Adsale Corporate|last=Website|website=www.adsale.com.hk|access-date=2020-05-24|archive-url=https://web.archive.org/web/20200502184124/https://www.adsale.com.hk/corporate/idx/eng/adsale_group|archive-date=2020-05-02|url-status=live}}</ref> At the exhibition, many western high-tech products, including [[Internet security]], [[video monitoring]] and human [[Facial recognition system|face recognition]] were purchased. It is estimated that around 30,000–50,000 police were employed in this gigantic project.<ref>{{Cite web |date=2015-04-27 |title=What is internet censorship? - Amnesty International Australia |url=http://www.amnesty.org.au/china/comments/10926/ |access-date=2023-12-28 |archive-url=https://web.archive.org/web/20150427065800/http://www.amnesty.org.au/china/comments/10926/ |archive-date=27 April 2015 }}</ref>

[[File:Fang binxing.jpg|thumb|left|Fang Binxing]]
[[Fang Binxing]] is known for his substantial contribution to [[Internet censorship in China|China's Internet censorship infrastructure]], and has been dubbed "Father of China's Great Fire Wall".<ref>{{cite web | url=https://chinadigitaltimes.net/2010/12/%E2%80%98father%E2%80%99-of-china%E2%80%99s-great-firewall-shouted-off-own-microblog/ | title='Father' of China's Great Firewall Shouted Off Own Microblog | work=[[China Digital Times]] (CDT) | date=20 December 2010 | access-date=24 October 2019 | first=Xiao | last=Qiang | archive-url=https://web.archive.org/web/20191225145914/https://chinadigitaltimes.net/2010/12/%e2%80%98father%e2%80%99-of-china%e2%80%99s-great-firewall-shouted-off-own-microblog/ | archive-date=25 December 2019 | url-status=live }}</ref><ref name=WSJ>{{cite news|url=https://blogs.wsj.com/chinarealtime/2010/12/20/father-of-chinas-great-firewall-shouted-off-own-microblog/|title='Father' of China's Great Firewall Shouted Off Own Microblog – China Real Time Report – WSJ|date=20 December 2010|work=[[The Wall Street Journal]]|access-date=25 December 2010|archive-url=https://web.archive.org/web/20171119154634/https://blogs.wsj.com/chinarealtime/2010/12/20/father-of-chinas-great-firewall-shouted-off-own-microblog/|archive-date=19 November 2017|url-status=live}}</ref><ref>{{cite web | publisher = Yunnan Information Times | script-title = zh:"防火墙之父"北邮校长方滨兴微博遭网民"围攻" | url = http://china.nfdaily.cn/content/2010-12/23/content_18691581.htm | date = 23 December 2010 | access-date = 20 May 2011 | language = zh | archive-url = https://web.archive.org/web/20110721182306/http://china.nfdaily.cn/content/2010-12/23/content_18691581.htm | archive-date = 21 July 2011 | url-status = dead }}</ref>

==Origins of Chinese Internet law==
China's view of the Internet is one of "[[Network sovereignty|Internet sovereignty]]": the notion that the Internet inside the country is part of the country's sovereignty and should be governed by the country.<ref name=WaPo2017/><ref>{{cite news|last1=Denyer|first1=Simon|title=China's scary lesson to the world: Censoring the Internet works|url=https://www.washingtonpost.com/world/asia_pacific/chinas-scary-lesson-to-the-world-censoring-the-internet-works/2016/05/23/413afe78-fff3-11e5-8bb1-f124a43f84dc_story.html|newspaper=[[The Washington Post]]|date=23 May 2016|access-date=2 September 2017|archive-url=https://web.archive.org/web/20181206113628/https://www.washingtonpost.com/world/asia_pacific/chinas-scary-lesson-to-the-world-censoring-the-internet-works/2016/05/23/413afe78-fff3-11e5-8bb1-f124a43f84dc_story.html|archive-date=6 December 2018|url-status=live}}</ref>

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 deals with 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 "[[classified information|state secrets]]."<ref>{{Cite web |title=Criminal Law of the People's Republic of China (1997) |url=http://www.npc.gov.cn/zgrdw/englishnpc/Law/2007-12/13/content_1384075.htm |access-date=2024-01-03 |website=www.npc.gov.cn |archive-date=6 January 2024 |archive-url=https://web.archive.org/web/20240106073907/http://www.npc.gov.cn/zgrdw/englishnpc/Law/2007-12/13/content_1384075.htm |url-status=live }}</ref>

Some Chinese judges were critical of CL97, calling it ineffective and unenforceable. However, the NPC claimed that 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 of the People's Republic of China|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 Chinese Communist Party has ended up relying heavily on state regulation to carry out CL97.<ref>{{cite book |last=Keith |first=Ronald |author2=Lin, Zhiqiu |title=New Crime in China |url=https://archive.org/details/newcrimechinapub00keit |url-access=limited |publisher=Routledge Taylor & Francis Group |date=2006 |pages=[https://archive.org/details/newcrimechinapub00keit/page/n229 217]–225 |isbn=0415314828 }}</ref>

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.{{citation needed|date=May 2018}}

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]].{{citation needed|date=May 2018}}<ref>{{Cite book|last=Anderson|first=Daniel|title=Splinternet Behind the Great Firewall of China: Once China opened its door to the world, it could not close it again.|publisher=Queue}}</ref>

==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 operated by civilians and supervised by China's national police force, the [[Chinese public security bureau|Public Security Bureau]] (PSB). The main operating procedures of the gatekeepers at the Golden Shield Project include monitoring domestic websites, 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 [[Block (Internet)|internet blocking]] by using proxy servers, among other strategies, to make communications and circumnavigate to blocked content.<ref name="OliverAugust">{{Cite magazine |url=http://archive.wired.com/politics/security/magazine/15-11/ff_chinafirewall |title=The Great Firewall: China's Misguided — and Futile — Attempt to Control What Happens Online |last=August |first=Oliver |date=23 October 2007 |magazine=[[Wired (magazine)|Wired Magazine]] |access-date=1 April 2015 |archive-url=https://web.archive.org/web/20150402093349/http://archive.wired.com/politics/security/magazine/15-11/ff_chinafirewall |archive-date=2 April 2015 |url-status=live }}</ref>

[[Internet Cafe|Internet cafés]], an extremely popular way of getting online in developing countries and 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 either local government officials or 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.<ref>{{cite web |url=https://www.washingtonpost.com/wp-dyn/content/article/2007/02/08/AR2007020802389_pf.html |title=Despite a Ban, Chinese Youth Navigate to Internet Cafés |date=9 February 2007 |access-date=1 April 2015 |newspaper=[[The Washington Post]] |last=Cody |first=Edward |archive-url=https://web.archive.org/web/20141220053356/http://www.washingtonpost.com/wp-dyn/content/article/2007/02/08/AR2007020802389_pf.html |archive-date=20 December 2014 |url-status=live }}</ref>

In May 2015, China indefinitely blocked access to the Chinese-language Wikipedia.<ref>{{cite news |last1=Smith |first1=Charlie |title=We Had Our Arguments, But We Will Miss You Wikipedia |url=https://www.huffingtonpost.com/charlie-smith/we-had-our-arguments-but-_b_7610130.html |access-date=31 December 2018 |work=Huffington Post |date=18 June 2015 |archive-url=https://web.archive.org/web/20150619083431/http://www.huffingtonpost.com/charlie-smith/we-had-our-arguments-but-_b_7610130.html |archive-date=19 June 2015 |url-status=live }}</ref> In 2017, China discussed plans for its own version of Wikipedia.<ref name=Verge2017>{{cite news|last1=Toor|first1=Amar|title=China is building its own version of Wikipedia|url=https://www.theverge.com/2017/5/4/15541016/china-wikipedia-encyclopedia-online-censorship|work=The Verge|date=4 May 2017|access-date=4 September 2017|archive-url=https://web.archive.org/web/20170904155402/https://www.theverge.com/2017/5/4/15541016/china-wikipedia-encyclopedia-online-censorship|archive-date=4 September 2017|url-status=live}}</ref><ref name=Indep2017>{{cite news|last1=Watt|first1=Louise|title=China is launching its own Wikipedia – but only the government can contribute to it|url=https://www.independent.co.uk/news/world/asia/china-wikipedia-chinese-version-government-no-public-authors-contributions-communist-party-line-a7717861.html|work=The Independent|date=4 May 2017|access-date=3 November 2017|archive-url=https://web.archive.org/web/20181210224316/https://www.dw.com/ar/%D8%A7%D9%84%D8%AD%D9%82%D9%88%D9%82%D9%8A-%D8%A7%D9%84%D8%B3%D9%88%D8%B1%D9%8A-%D8%A3%D9%86%D9%88%D8%B1-%D8%A7%D9%84%D8%A8%D9%86%D9%8A-%D9%8A%D8%AA%D8%B3%D9%84%D9%85-%D8%AC%D8%A7%D8%A6%D8%B2%D8%A9-%D8%A3%D9%84%D9%85%D8%A7%D9%86%D9%8A%D8%A9-%D9%80-%D9%81%D8%B1%D9%86%D8%B3%D9%8A%D8%A9/a-46669373|archive-date=10 December 2018|url-status=live}}</ref> As of May 2019, all language versions of Wikipedia have been blocked by the Chinese government.<ref>{{cite news|url=https://www.washingtonpost.com/business/2019/05/15/china-bans-wikipedia-all-languages/|title=Search result not found: China bans Wikipedia in all languages|newspaper=Washington Post|language=en|access-date=6 June 2019|archive-url=https://web.archive.org/web/20190607003155/https://www.washingtonpost.com/business/2019/05/15/china-bans-wikipedia-all-languages/|archive-date=7 June 2019|url-status=live}}</ref>

==Blocking methods==
[[File:Topology of the Chinese firewall.svg|thumb|Topology of the Great Firewall]]

The Great Firewall is mainly deployed at three large internet exchanges in Beijing, Shanghai, and Guangzhou.<ref name=roya2014>{{cite arXiv
|title=Large-scale Spatiotemporal Characterization of Inconsistencies in the World's Largest Firewall
|date=2014-10-03
|eprint=1410.0735
|author1=Roya Ensafi|author2=Philipp Winter|author3=Abdullah Mueen|author4=Jedidiah R. Crandall
|class=cs.NI
}}</ref><ref name=solidot1014>{{cite web
|url=http://www.solidot.org/story?sid=41450
|date=2014-10-14
|work=[[Solidot]]
|title=分析防火长城的故障模式
|author=WinterIsComing
|url-status=dead
|access-date=2024-04-19
|archive-url=https://web.archive.org/web/20150101164241/http://www.solidot.org/story?sid=41450
|archive-date=2015-01-01
}}</ref>

===Active filtering===
One function of the Chinese firewall is to selectively prevent content from being accessed. It is mostly made of Cisco, Huawei, and Semptian hardware.<ref>{{cite web|url=https://www.forbes.com/sites/arthurherman/2018/12/10/huaweis-and-chinas-dangerous-high-tech-game/|title=Huawei's (And China's) Dangerous High-Tech Game|last=Herman|first=Arthur|website=Forbes|language=en|access-date=8 October 2019|archive-url=https://web.archive.org/web/20190515103447/https://www.forbes.com/sites/arthurherman/2018/12/10/huaweis-and-chinas-dangerous-high-tech-game/|archive-date=15 May 2019|url-status=live}}</ref><ref>{{cite web|url=https://c5is.com/cisco-huawei-and-semptian-a-look-behind-the-great-firewall-of-china/|title=Cisco, Huawei and Semptian: A Look Behind the Great Firewall of China|date=15 December 2014|website=C5IS|language=en-US|access-date=8 October 2019|archive-url=https://web.archive.org/web/20190714193154/https://c5is.com/cisco-huawei-and-semptian-a-look-behind-the-great-firewall-of-china/|archive-date=14 July 2019|url-status=live}}</ref> Not all sensitive content gets blocked; in 2007, scholar Jedidiah R. Crandall and others argued that the main purpose is not to block 100%, but rather to flag and to warn, in order to encourage self-censorship.<ref>{{cite book |author1=Oliver Farnan |author2=Alexander Darer |author3=Joss Wright |title=Proceedings of the 2016 ACM on Workshop on Privacy in the Electronic Society - WPES'16 |chapter=Poisoning the Well |year=2016 |pages=95–98 |doi=10.1145/2994620.2994636 |isbn=9781450345699 |s2cid=7275132 }}</ref> An illustrative but incomplete list of tactics includes:

{| class="wikitable"
|-
!Method
!Description
|-
|IP range ban using [[Black hole (networking)|black holes]]
|The Chinese firewall maintains a list of [[IP address|IP ranges]] that are automatically dropped ([[Black hole (networking)|network black-holing]]).<ref>{{Cite web |title=Forbidden: China Geo-Blocking Americans from Accessing Supreme People's Court Website and Published Decisions|url=https://www.chinaiplawupdate.com/2022/11/forbidden-china-geo-blocking-americans-from-accessing-supreme-peoples-court-website-and-published-decisions/ |access-date=2025-01-17 |website=www.chinaiplawupdate.com}}</ref>

Because of the complexity involved in maintaining a large, up-to-date banned network list with dynamic IPs (and as this method has proven incompatible with services using [[content delivery network]]s) it is usually used as a last resort, with other blocking methods preferred (such as filtering based on [[Quality of service|QoS]]). 
|-
|[[DNS spoofing]], filtering and redirection
|One part of the Chinese firewall is made of liar DNS servers and [[DNS hijacking|DNS hijackers]] returning incorrect IP addresses.<ref>{{cite web |url=http://pcwizardpro.com/how-to-unblock-websites-in-china/ |title=how to unblock websites in China |date=26 January 2018 |publisher=pcwizardpro.com |access-date=27 January 2018 |archive-url=https://web.archive.org/web/20180127084214/http://pcwizardpro.com/how-to-unblock-websites-in-china/ |archive-date=27 January 2018 |url-status=live }}</ref> Studies seems to point out that this censorship is keyword-based.<ref name=":0">{{cite web|url=https://www.usenix.org/system/files/conference/foci14/foci14-anonymous.pdf|title=The Great DNS Wall of China - Analysis of the DNS infrastructure|access-date=2019-06-01|archive-url=https://web.archive.org/web/20190403121058/https://www.usenix.org/system/files/conference/foci14/foci14-anonymous.pdf|archive-date=2019-04-03|url-status=live}}</ref>

Contrary to popular belief,<ref>{{cite web|url=https://news.ycombinator.com/item?id=16772035|title=8.8.8.8 goes pretty well in the Chinese market. (8 being a popular number.) I th... {{!}} Hacker News|website=news.ycombinator.com|access-date=31 May 2019|archive-url=https://web.archive.org/web/20200326175426/https://news.ycombinator.com/item?id=16772035|archive-date=26 March 2020|url-status=live}}</ref> foreign DNS resolvers such as [[Google Public DNS]] IP address 8.8.8.8 are reported to work correctly inside the country; however, these DNS servers are also subject to hijacking as their connections are not encrypted: DNS queries do reach the DNS server, but if the request matches a banned keyword, the firewall will inject a fake DNS reply before the legitimate DNS reply arrives. The vast majority of these fake responses contain public IP addresses of U.S. companies, including Facebook, Twitter, and Dropbox.<ref>{{Cite arXiv |last1=Hoang |first1=Nguyen Phong |last2=Niaki |first2=Arian Akhavan |last3=Dalek |first3=Jakub |last4=Knockel |first4=Jeffrey |last5=Lin |first5=Pellaeon |last6=Marczak |first6=Bill |last7=Crete-Nishihata |first7=Masashi |last8=Gill |first8=Phillipa |last9=Polychronakis |first9=Michalis |date=2021-06-03 |title=How Great is the Great Firewall? Measuring China's DNS Censorship |class=cs.CR |eprint=2106.02167 }}</ref>

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]]/[[DNS over HTTPS|HTTPS]].<ref>{{Cite arXiv |last1=Hoang |first1=Nguyen Phong |last2=Polychronakis |first2=Michalis |last3=Gill |first3=Phillipa |date=2022-02-01 |title=Measuring the Accessibility of Domain Name Encryption and Its Impact on Internet Filtering |class=cs.NI |eprint=2202.00663 }}</ref>
|-
|[[Uniform Resource Locator|URL]] filtering using transparent proxies
|The Chinese firewall is made of [[Transparent proxy|transparent proxies]] filtering web traffic. These proxies scan the requested [[Uniform Resource Identifier|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.<ref>{{cite web |url=https://blog.xeovo.com/what-is-the-great-firewall-of-china-and-why-you-should-care/ |title=What is the Great Firewall of China and why you should care |date=30 December 2021 |publisher=xeovo.com |access-date=2 January 2024 |archive-date=8 August 2024 |archive-url=https://web.archive.org/web/20240808050047/https://blog.xeovo.com/what-is-the-great-firewall-of-china-and-why-you-should-care/ |url-status=live }}</ref>

Like for DNS filtering, this method is keyword-based. Encrypting the Server Name Indication (Encrypted Client Hello or ECH) can be used to bypass this method of filtering. It is currently in development by the [[Internet Engineering Task Force|IETF]],<ref>{{cite news|url=https://datatracker.ietf.org/doc/draft-ietf-tls-esni/|title=draft-ietf-tls-esni-03 - Encrypted Server Name Indication for TLS 1.3|newspaper=Ietf Datatracker|access-date=13 June 2019|archive-url=https://web.archive.org/web/20190606041824/https://datatracker.ietf.org/doc/draft-ietf-tls-esni/|archive-date=6 June 2019|url-status=live}}</ref> and is enabled by default for supported websites in [[Firefox]] and [[Chromium (web browser)|Chromium]] ([[Google Chrome]], [[Microsoft Edge]], [[Samsung Internet]], and [[Opera (web browser)|Opera]]).<ref>{{cite web|url=https://blog.mozilla.org/security/2018/10/18/encrypted-sni-comes-to-firefox-nightly/|title=Encrypted SNI Comes to Firefox Nightly|website=Mozilla Security Blog|date=18 October 2018 |access-date=2020-02-11|archive-url=https://web.archive.org/web/20200324233735/https://blog.mozilla.org/security/2018/10/18/encrypted-sni-comes-to-firefox-nightly/|archive-date=2020-03-24|url-status=live}}</ref><ref>{{cite web|url=https://blog.cloudflare.com/encrypt-that-sni-firefox-edition/|title=Encrypt that SNI: Firefox edition|date=October 18, 2018|website=The Cloudflare Blog|access-date=February 11, 2020|archive-url=https://web.archive.org/web/20200214223249/https://blog.cloudflare.com/encrypt-that-sni-firefox-edition/|archive-date=February 14, 2020|url-status=live}}</ref><ref>{{cite web |url=https://chasersystems.com/blog/disabling-encrypted-clienthello-in-google-chrome-and-why/ |title=How to disable TLS Encrypted ClientHello in Google Chrome using PowerShell |author=<!--Not stated--> |date=9 October 2023 |website= |publisher=Chaser Systems Ltd |access-date= |quote= |archive-date=21 February 2024 |archive-url=https://web.archive.org/web/20240221182758/https://chasersystems.com/blog/disabling-encrypted-clienthello-in-google-chrome-and-why/ |url-status=live }}</ref><ref>{{cite web |url=https://chromestatus.com/feature/6196703843581952 |title=Feature: TLS Encrypted Client Hello (ECH) |author=<!--Not stated--> |date=12 December 2023 |website=Chrome Platform Status |publisher=[[Google]] |access-date=21 February 2024 |quote= |archive-date=22 January 2024 |archive-url=https://web.archive.org/web/20240122130352/https://chromestatus.com/feature/6196703843581952 |url-status=live }}</ref>

However, in July 2020, [[iYouPort]], the [[The University of Maryland|University of Maryland]], and the [[Great Firewall Report]], reported that the GFW blocks TLS connections using some encrypted SNI extension in China.
|-
|[[Quality of service]] filtering
|Since 2012, the GFW is able to "learn, filter, and block" users based on traffic behavior, using [[deep packet inspection]].<ref name="guardvpn2">{{cite news|url=https://www.theguardian.com/technology/2012/dec/14/china-tightens-great-firewall-internet-control|title=China tightens 'Great Firewall' internet control with new technology|last=Arthur|first=Charles|date=14 December 2012|work=guardian.co.uk|access-date=8 March 2013|publisher=The Guardian|location=London|archive-url=https://web.archive.org/web/20130910001533/http://www.theguardian.com/technology/2012/dec/14/china-tightens-great-firewall-internet-control|archive-date=10 September 2013|url-status=live}}</ref> This method was originally developed for blocking VPNs and has been extended to become part of the standard filtering system of the GFW. The 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 deemed to be. This score is then used to determine a [[Packet loss|packet loss rate]] to be implemented by routers of the Chinese firewall, resulting in a slowed connection on the client side. The method aims to slow down traffic to such an extent that the request times out on the client side, thus effectively having succeeded in blocking the service altogether.

It is believed that the analytics system is using [[Side-channel attack|side-channel]] (such as the handshake headers, and packet sizes) to estimate how suspicious a connection is.<ref>{{cite web|url=http://blog.zorinaq.com/my-experience-with-the-great-firewall-of-china/|title=My Experience With the Great Firewall of China|website=blog.zorinaq.com|language=en|access-date=1 June 2019|archive-url=https://web.archive.org/web/20160701195829/http://blog.zorinaq.com/my-experience-with-the-great-firewall-of-china/|archive-date=1 July 2016|url-status=live}}{{Self-published source|date=October 2020}}</ref> It is able to detect traffic protocols (such as SSH tunneling, [[Virtual private network|VPN]] or [[Tor (anonymity network)|Tor]] protocols), and can measure the [[Entropy (information theory)|entropy]] of packets to detect encrypted-over-encrypted traffic (such as HTTPS over an SSL tunnel).

This attack may be resisted by using a pluggable transport in order to mimic 'innocent' traffic, and never connect to 'suspicious' IPs by always having the circumvention software turned on, yet not proxy unblocked content, and the software itself never directly connects to a central server.<ref>{{cite web|url=https://www.usenix.org/system/files/conference/foci12/foci12-final2.pdf|title=How the Great Firewall of China is blocking Tor|access-date=2022-01-27|archive-url=https://web.archive.org/web/20220127204429/https://www.usenix.org/system/files/conference/foci12/foci12-final2.pdf|archive-date=2022-01-27|url-status=live}}</ref>
|-
| Packet forging and [[TCP reset attack]]s
|The Chinese firewall may arbitrarily terminate TCP transmissions, using [[Packet injection|packet forging]]. The blocking is performed using a TCP reset attack. This attack does not block TCP requests nor TCP replies, but sends a malicious TCP RST packet to the sender, simulating an end-of-connection. Recent research has also confirmed that these TCP reset behaviors are not only observable from within China, but can also be detected from outside the country. In particular, a 2024 study showed that the firewall engages in TCP non-compliant behavior, including bidirectional resets, allowing external observers to identify and measure censorship remotely.<ref>{{Cite journal |last=Hoang |first=Nguyen Phong |last2=Dalek |first2=Jakub |last3=Crete-Nishihata |first3=Masashi |last4=Christin |first4=Nicolas |last5=Yegneswaran |first5=Vinod |last6=Polychronakis |first6=Michalis |last7=Feamster |first7=Nick |date=2024 |title=GFWeb: Measuring the Great Firewall's Web Censorship at Scale |url=https://www.usenix.org/conference/usenixsecurity24/presentation/hoang |journal=The 33rd USENIX Security Symposium |language=en |pages=2617–2633 |isbn=978-1-939133-44-1}}</ref>

Side channel analysis seems to indicate that TCP Resets are coming from an infrastructure co-located or shared with QoS filtering routers.<ref>{{cite web|url=https://www.cl.cam.ac.uk/~rnc1/ignoring.pdf|title=Ignoring TCP RST send by the firewall|access-date=2019-06-01|archive-url=https://web.archive.org/web/20190611203524/https://www.cl.cam.ac.uk/~rnc1/ignoring.pdf|archive-date=2019-06-11|url-status=live}}</ref> 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 periods of time (up to a few hours).

An efficient circumvention method is to ignore the reset packet sent by the firewall.<ref>{{cite web|url=http://www.zdnetasia.com/news/security/0,39044215,39372326,00.htm|title=zdnetasia.com|publisher=zdnetasia.com|access-date=13 June 2011|archive-url=https://web.archive.org/web/20091008214629/http://www.zdnetasia.com/news/security/0,39044215,39372326,00.htm|archive-date=8 October 2009|url-status=live}}</ref> A patch for FreeBSD has been developed for this purpose.<ref>{{cite web|url=https://www.cl.cam.ac.uk/~rnw24/patches/20060607-tcp-ttl.diff|title=FreeBSD patch - ignore TCP RST|access-date=2019-06-01|archive-url=https://web.archive.org/web/20080629073234/http://www.cl.cam.ac.uk/~rnw24/patches/20060607-tcp-ttl.diff|archive-date=2008-06-29|url-status=live}}</ref>

|-
|[[Man-in-the-middle attack]] with TLS
|The [[National Intelligence Law of the People's Republic of China]] theoretically allows the Chinese government to request and use the root certificate from any Chinese certificate authority,<ref>{{cite web|url=https://www.dezshira.com/library/legal/cyber-security-law-china-8013.html|title=Cyber-security Law of the People's Republic of China|website=www.dezshira.com|date=11 January 2018 |language=en|access-date=1 June 2019|archive-url=https://web.archive.org/web/20190601010621/https://www.dezshira.com/library/legal/cyber-security-law-china-8013.html|archive-date=1 June 2019|url-status=live}}</ref> such as [[CNNIC]], to make MITM attacks with valid certificates.

Multiple TLS incidents have occurred within the last decade, before the creation of the law.

On 26 January 2013, the [[GitHub]] SSL certificate was replaced with a self-signed certificate in China.<ref>{{cite web|url=http://news.ycombinator.com/item?id=5124784|title=GitHub SSL replaced by self-signed certificate in China &#124; Hacker News|publisher=News.ycombinator.com|access-date=15 June 2013|archive-url=https://web.archive.org/web/20140705135606/https://news.ycombinator.com/item?id=5124784|archive-date=5 July 2014|url-status=live}}</ref>

On 20 October 2014, the iCloud SSL certificate was replaced with a self-signed certificate in China.<ref>{{cite web|url=https://www.netresec.com/?page=Blog&month=2014-10&post=Chinese-MITM-Attack-on-iCloud|title=Chinese MITM Attack on iCloud - NETRESEC Blog|website=Netresec|date=20 October 2014|access-date=2019-06-10|archive-url=https://web.archive.org/web/20200329044228/https://www.netresec.com/?page=Blog&month=2014-10&post=Chinese-MITM-Attack-on-iCloud|archive-date=2020-03-29|url-status=live}}</ref> It is believed that the Chinese government discovered a vulnerability on Apple devices and was exploiting it.<ref>{{CVE|2014-4449}}</ref>

On 20 March 2015, Google detected valid certificates for Google signed by CNNIC in Egypt. In response to this event, and after a deeper investigation, the CNNIC certificate was removed by some browsers.<ref>{{cite web|url=https://nakedsecurity.sophos.com/2015/04/14/tls-certificate-blunder-revisited-whither-china-internet-network-information-center/|title=TLS certificate blunder revisited – whither China Internet Network Information Center?|publisher=nakedsecurity.sophos.com|access-date=18 October 2018|date=2015-04-14|archive-url=https://web.archive.org/web/20181021232209/https://nakedsecurity.sophos.com/2015/04/14/tls-certificate-blunder-revisited-whither-china-internet-network-information-center/|archive-date=21 October 2018|url-status=live}}</ref> Due to the removal being based on proof and not suspicion, no other Chinese certificate authority has been removed from web browsers, and some have been added since then.<ref>{{cite web|url=https://bugzilla.mozilla.org/show_bug.cgi?id=1128392|title=1128392 - Add GDCA Root Certificate|website=bugzilla.mozilla.org|language=en|access-date=1 June 2019|archive-url=https://web.archive.org/web/20200324235853/https://bugzilla.mozilla.org/show_bug.cgi?id=1128392|archive-date=24 March 2020|url-status=live}}</ref>

This type of attack can be circumvented by websites implementing [[Certificate Transparency]] and [[OCSP stapling]] or by using browser extensions.<ref>{{cite web|url=http://patrol.psyced.org/|title=Certificate Patrol - a psyced Firefox/Mozilla add-on|website=patrol.psyced.org|access-date=7 July 2019|archive-url=https://web.archive.org/web/20190613113932/http://patrol.psyced.org/|archive-date=13 June 2019|url-status=live}}</ref>
|}

=== Active probing ===
In addition to previously discussed techniques, the [[Cyberspace Administration of China|CAC]] is also using [[Network mapping#Active probing|active probing]] in order to identify and block network services that would help escaping the firewall. Multiple services such as [[Tor (anonymity network)|Tor]] or [[VPN]] providers reported receiving unsolicited TCP/IP connections shortly after legitimate use, for the purported purpose of [[network enumerating|network enumeration]] of services, in particular [[Transport Layer Security|TLS]]/[[Secure Sockets Layer|SSL]] and Tor services, with the aim of facilitating IP blocking. For example, shortly after a VPN request is issued by a legitimate Chinese VPN client and passes outbound though the Great Firewall to a hidden VPN IP, the Great Firewall may detect the activity and issue its own active probe to verify the nature of the previously unknown VPN IP and, if the probe confirms the IP is part of a blacklisted VPN, blacklist the IP.<ref name="auto">{{cite web|url=https://blog.torproject.org/blog/knock-knock-knockin-bridges-doors|title=Knock Knock Knockin' on Bridges' Doors|last=Wilde|first=Tim|date=7 January 2012|publisher=[[Tor Project]]|access-date=3 May 2018|archive-url=https://web.archive.org/web/20120113060455/https://blog.torproject.org/blog/knock-knock-knockin-bridges-doors|archive-date=13 January 2012|url-status=live}}</ref><ref name="blog.torproject.org">{{cite web|url=https://blog.torproject.org/learning-more-about-gfws-active-probing-system|title=Learning more about the GFW's active probing system {{!}} Tor Blog|website=blog.torproject.org|access-date=8 October 2019|archive-url=https://web.archive.org/web/20191008214120/https://blog.torproject.org/learning-more-about-gfws-active-probing-system|archive-date=8 October 2019|url-status=live}}</ref> This attack can be circumvented with the Obfs4 protocol, which relies on an out-of-band [[shared secret]].<ref name="auto"/><ref name="blog.torproject.org"/>

=== Proxy distribution ===
The Great Firewall scrapes the IPs of Tor and VPN servers from the official distribution channels, and enumerates them.<ref>{{cite web |url=https://www.youtube.com/watch?v=DX46Qv_b7F4&t=831 |title=28c3: How governments have tried to block Tor |publisher=YouTube |date=2011-12-28 |access-date=2020-02-17 |archive-url=https://web.archive.org/web/20200329110424/https://www.youtube.com/watch?v=DX46Qv_b7F4&t=831 |archive-date=2020-03-29 |url-status=live }}</ref><ref>{{cite web |url=https://www.youtube.com/watch?v=ZB8ODpw_om8&t=743 |title=Roger Dingledine - The Tor Censorship Arms Race The Next Chapter - DEF CON 27 Conference |publisher=YouTube |date=2019-11-15 |access-date=2020-02-17 |archive-url=https://web.archive.org/web/20200329111727/https://www.youtube.com/watch?v=ZB8ODpw_om8&t=743 |archive-date=2020-03-29 |url-status=live }}</ref><ref>{{cite web|url=https://trac.torproject.org/projects/tor/ticket/32117|title=#32117 (Understand and document BridgeDB bot scraping attempts) – Tor Bug Tracker & Wiki|website=trac.torproject.org|date=16 October 2019 |access-date=2020-01-21|archive-url=https://web.archive.org/web/20200327035436/https://trac.torproject.org/projects/tor/ticket/32117|archive-date=2020-03-27|url-status=live}}</ref><ref>{{cite web |url=https://www.youtube.com/watch?v=Wxpl8naHQCs |title=Jinyang Li - Censorship Circumvention via Kaleidoscope |date=31 March 2010 |publisher=YouTube |access-date=2020-05-24 |archive-url=https://web.archive.org/web/20200523012421/https://www.youtube.com/watch?v=Wxpl8naHQCs |archive-date=2020-05-23 |url-status=live }}</ref> The strategy to resist this attack is to limit the quantity of proxy IPs revealed to each user and making it very difficult for users to create more than one identity.<ref>{{cite web |url=https://people.cs.umass.edu/~amir/papers/TorGame.pdf |title=Tor Games |publisher=people.cs.umass.edu |access-date=2020-02-17 |archive-url=https://web.archive.org/web/20200217222223/https://people.cs.umass.edu/~amir/papers/TorGame.pdf |archive-date=2020-02-17 |url-status=live }}</ref><ref>{{cite web |url=https://www-users.cs.umn.edu/~hoppernj/rbridge_ndss13.pdf |title=Data |publisher=www-users.cs.umn.edu |access-date=2020-02-17 |archive-url=https://web.archive.org/web/20190612072343/https://www-users.cs.umn.edu/~hoppernj/rbridge_ndss13.pdf |archive-date=2019-06-12 |url-status=live }}</ref><ref>{{cite web |url=https://censorbib.nymity.ch/pdf/Sovran2008a.pdf |title=Info |publisher=censorbib.nymity.ch |access-date=2020-05-24 |archive-url=https://web.archive.org/web/20160317075430/https://censorbib.nymity.ch/pdf/Sovran2008a.pdf |archive-date=2016-03-17 |url-status=live }}</ref> Academics have proposed solutions such as Salmon, a volunteer-based proxy network designed to combat censorship.<ref>{{cite web |url=https://censorbib.nymity.ch/pdf/Douglas2016a.pdf |title=Info |publisher=censorbib.nymity.ch |access-date=2020-05-24 |archive-date=8 August 2024 |archive-url=https://web.archive.org/web/20240808050043/https://censorbib.nymity.ch/pdf/Douglas2016a.pdf |url-status=live }}</ref><ref>{{cite web |url=https://www.youtube.com/watch?v=RO3wXRn8BfY |title=Frederick Douglas - Salmon: Robust Proxy Distribution for Censorship Circumvention |publisher=YouTube |date=2016-10-10 |access-date=2020-05-24 |archive-url=https://web.archive.org/web/20190204190605/https://www.youtube.com/watch?v=RO3wXRn8BfY |archive-date=2019-02-04 |url-status=live }}</ref><ref>{{cite web |url=https://community.torproject.org/gsoc/salmon-bridge-distribution/ |url-status=dead |archive-url=https://web.archive.org/web/20200626231844/https://community.torproject.org/gsoc/salmon-bridge-distribution/ |archive-date=2020-06-26 |title=Tor Project {{!}} Implementing Salmon as a bridge distribution mechanism}}</ref><ref>{{Cite web|url = https://github.com/net4people/bbs/issues/33|title = Salmon: Robust Proxy Distribution for Censorship Circumvention (PETS 2016) · Issue #33 · net4people/BBS|website = [[GitHub]]|access-date = 24 June 2020|archive-date = 30 November 2020|archive-url = https://web.archive.org/web/20201130083139/https://github.com/net4people/bbs/issues/33|url-status = live}}</ref> Dynamic IPs are quite effective to flush out from blacklists.

==Goals, impact and resistance==

=== Goal of the Firewall ===
Article 15 of a 20 September 2000 document from the [[State Council of the People's Republic of China|Chinese State Council]], posted by the Xinhua News Agency, lists 9 categories of information which should be [[Censorship in China|censored]], blocked, or filtered from access to the citizens using the internet within China:

# Opposing the basic principles as they are confirmed in the Constitution.
# Jeopardizing the security of the nation, divulging state secrets, subverting state power, or jeopardizing the integrity of the nation's unity
# Harming the honor or the interests of the nation
# Inciting hatred against peoples, racism against peoples, or disrupting the solidarity of peoples
# Disrupting national policies on religion, propagating evil cults and feudal superstitions
# Spreading rumors, disturbing social order or disrupting social stability
# Spreading obscenity, pornography, gambling, violence, murder, terror, or abetting the commission of a crime
# Insulting or defaming third parties, infringing on the legal rights and interests of third parties
# Containing any other content prohibited by law or administrative rules<ref>{{Cite web|date=September 25, 2000|title=Measures for the Administration of Internet Information Services|url=https://www.cecc.gov/resources/legal-provisions/measures-for-the-administration-of-internet-information-services-cecc|access-date=April 21, 2021|website=Congressional-Executive Commission on China|archive-date=8 August 2024|archive-url=https://web.archive.org/web/20240808050045/https://www.cecc.gov/resources/legal-provisions/measures-for-the-administration-of-internet-information-services-cecc|url-status=live}}</ref>

To filter this content, the Chinese government not only uses its own blocking methods, but also heavily relies on internet companies, such as ISPs, social media operators such as Weibo,<ref>{{Cite news|last=Griffiths|first=James|date=March 20, 2019|title=Weibo's Free-Speech Failure|work=The Atlantic|url=https://www.theatlantic.com/technology/archive/2019/03/what-went-wrong-chinas-weibo-social-network/584728/|access-date=April 21, 2021|archive-date=1 October 2020|archive-url=https://web.archive.org/web/20201001213308/https://www.theatlantic.com/technology/archive/2019/03/what-went-wrong-chinas-weibo-social-network/584728/|url-status=live}}</ref> and others to actively censor their users.<ref>“[https://pen.org/wp-content/uploads/2018/06/PEN-America_Forbidden-Feeds-report-6.6.18.pdf FORBIDDEN FEEDS: Government Controls on Social Media in China] {{Webarchive|url=https://web.archive.org/web/20211118234716/https://pen.org/wp-content/uploads/2018/06/PEN-America_Forbidden-Feeds-report-6.6.18.pdf |date=18 November 2021 }}," ''PEN America''. (March 13, 2018) p. 33.</ref> This results in private companies censoring their own platform for filtered content, forcing Chinese internet users to use websites not hosted in China to access this information. Much of this information is related to sensitive topics.<ref name=":02">“[https://pen.org/wp-content/uploads/2018/06/PEN-America_Forbidden-Feeds-report-6.6.18.pdf FORBIDDEN FEEDS: Government Controls on Social Media in China] {{Webarchive|url=https://web.archive.org/web/20211118234716/https://pen.org/wp-content/uploads/2018/06/PEN-America_Forbidden-Feeds-report-6.6.18.pdf |date=18 November 2021 }}," ''PEN America''. (March 13, 2018) p. 24.</ref> The Great Firewall's goal is perceived by the Chinese Communist Party as helping to protect the Chinese population by preventing users from accessing these foreign websites which, in their opinion, host content which would be 'spiritual pollution', as well as information about these sensitive topics.<ref name=":1">{{Cite journal|last=Abbott|first=Jason|date=April 30, 2019|title=Of Grass Mud Horses and Rice Bunnies: Chinese Internet Users Challenge Beijing's Censorship and Internet Controls|url=https://doi.org/10.1111/aspp.12442|journal=Asian Politics & Policy|volume=11|pages=162–168|doi=10.1111/aspp.12442|s2cid=159308868|access-date=21 April 2021|archive-date=8 August 2024|archive-url=https://web.archive.org/web/20240808050052/https://onlinelibrary.wiley.com/doi/10.1111/aspp.12442|url-status=live|url-access=subscription}}</ref> These topics include:

* Names of [[paramount leader]]s, such as [[Xi Jinping]] and [[Deng Xiaoping]]
* [[Protest and dissent in China|Political movements and protests]]
* [[Falun Gong]] and other spiritual groups
* The [[1989 Tiananmen Square protests|Tiananmen Square Massacre]]
* The [[Xinjiang internment camps]]
* Discussions of [[Tibetan independence movement|Tibetan Independence]]<ref>{{Cite news|last=Xiao|first=Qiang|date=April 30, 2009|title=Baidu's internal monitoring and censorship document leaked|work=China Digital Times|url=https://chinadigitaltimes.net/2009/04/baidus-internal-monitoring-and-censorship-document-leaked/|access-date=April 20, 2021|archive-date=19 April 2021|archive-url=https://web.archive.org/web/20210419185003/https://chinadigitaltimes.net/2009/04/baidus-internal-monitoring-and-censorship-document-leaked/|url-status=live}}</ref><ref>{{Cite news|last=Shu|first=Catherine|date=June 3, 2019|title=A Look at the many ways China suppresses online discourse about the Tiananmen Square protests|work=Tech Crunch|url=https://techcrunch.com/2019/06/03/a-look-at-the-many-ways-china-suppresses-online-discourse-about-the-tiananmen-square-protests/|access-date=April 20, 2021|archive-date=21 April 2021|archive-url=https://web.archive.org/web/20210421202820/https://techcrunch.com/2019/06/03/a-look-at-the-many-ways-china-suppresses-online-discourse-about-the-tiananmen-square-protests/|url-status=live}}</ref><ref>“[https://pen.org/wp-content/uploads/2018/06/PEN-America_Forbidden-Feeds-report-6.6.18.pdf FORBIDDEN FEEDS: Government Controls on Social Media in China] {{Webarchive|url=https://web.archive.org/web/20211118234716/https://pen.org/wp-content/uploads/2018/06/PEN-America_Forbidden-Feeds-report-6.6.18.pdf |date=18 November 2021 }}," PEN America. (March 13, 2018) p. 41-42.</ref>

A 2020 study found that the Great Firewall blocks approximately 311,000 domains.<ref name=":Zhang">{{Cite book |last=Zhang |first=Angela Huyue |title=High Wire: How China Regulates Big Tech and Governs Its Economy |publisher=[[Oxford University Press]] |year=2024 |isbn=9780197682258 |doi=10.1093/oso/9780197682258.001.0001}}</ref><ref name=":3" />

=== Impact on people in China ===
The [[Cybersecurity Law of the People's Republic of China|Cybersecurity Law]] behind the firewall is targeted at helping increase internet user privacy, increase protections on personal data, and making companies more responsible for monitoring bad actors, in hopes to make the Internet a safer place for Chinese citizens.<ref>{{Cite news|last=Wang|first=Hairong|date=January 17, 2013|title="Legal Firewall" Beijing Review|work=Beijing Review|url=http://www.bjreview.com/print/txt/2013-01/14/content_512143.htm|access-date=April 21, 2021|archive-date=21 April 2021|archive-url=https://web.archive.org/web/20210421202821/http://www.bjreview.com/print/txt/2013-01/14/content_512143.htm|url-status=live}}</ref> Despite this, there have been growing criticisms that the actions of the Chinese government have only hurt Chinese free speech, due to increased censorship, and lack of non-sanctioned sources of information, such as Wikipedia and many English news sources.<ref name=":3">{{Cite journal|last1=Pan|first1=Jennifer|last2=Roberts|first2=Margaret|date=January 2020|title=Censorship's Effect on Incidental Exposure to Information: Evidence from Wikipedia|journal=SAGE Open|volume=10|doi=10.1177/2158244019894068|doi-access=free}}</ref> This has resulted in reports of some cases of legal persecution of those charged with spreading this information.<ref name=":1" />

The Chinese government itself does legally support free speech; article 35 of the [[Constitution of China]] states that "citizens of the People's Republic of China enjoy [[freedom of speech]], of the [[Freedom of press|press]], of [[Freedom of assembly|assembly]], of association, of procession, and of demonstration."<ref>[http://en.people.cn/constitution/constitution.html "CONSTITUTION OF THE PEOPLE'S REPUBLIC OF CHINA". People's Daily. December] {{Webarchive|url=https://web.archive.org/web/20200609090748/http://en.people.cn/constitution/constitution.html |date=2020-06-09 }} (4, 1982) Archived from the original on August 12, 2010. Retrieved April 20, 2021.</ref> In recent decades, many criticisms of the Chinese government found that some of these laws are often abused. A study by [[PEN America]] claimed that "Some of the government's most rights-abusive laws are aimed at criminalizing free speech that — in the eyes of the government — encourages subversion, separatism, or rejection of the State’s authority."<ref name=":02" />

Censorship of sensitive topics in China has also been easier for the government because of the firewall and its filtering. Because the monitoring of social media and chat apps in China presents a possibility of punishment for a user, the discussion of these topics is now limited to the thought of the Chinese Communist Party, or one's home and private spaces, reducing the chance for information about these topics to spread, reducing any threat of protest against the CCP.<ref name=":2">{{Cite news|last=Wang|first=Yaqiu|date=September 1, 2020|title=In China, the 'Great Firewall' is Changing a Generation|work=Politico|url=https://www.politico.com/news/magazine/2020/09/01/china-great-firewall-generation-405385|access-date=April 20, 2021|archive-date=21 April 2021|archive-url=https://web.archive.org/web/20210421202819/https://www.politico.com/news/magazine/2020/09/01/china-great-firewall-generation-405385|url-status=live}}</ref><ref>{{Cite web|title=Freedom of Expression in China: A Privilege, Not a Right|url=https://www.cecc.gov/freedom-of-expression-in-china-a-privilege-not-a-right|access-date=April 20, 2021|website=Congressional-Executive Commission on China|date=30 August 2012 |archive-date=19 April 2021|archive-url=https://web.archive.org/web/20210419120225/https://www.cecc.gov/freedom-of-expression-in-china-a-privilege-not-a-right|url-status=live}}</ref> According to [[Yaqiu Wang]], a prominent human rights researcher, there was a time in China where the internet provided a method for Chinese citizens to learn about the sensitive topics the government had censored in the news, through access to international news reports and media coverage. She claims that, in the past 10 years, it has been increasingly difficult to access second opinions on events, meaning that students rarely have the opportunity to learn diverging viewpoints — only the "correct" thought of the CCP.<ref name=":2" />

=== Economic impacts ===
The Great Firewall has also allowed China to develop its own major internet services, such as [[Tencent]], [[Alibaba Group|Alibaba]], [[Baidu]],<ref name="washingtonpost.com2">{{cite news|last1=Denyer|first1=Simon|date=23 May 2016|title=China's scary lesson to the world: Censoring the Internet works|url=https://www.washingtonpost.com/world/asia_pacific/chinas-scary-lesson-to-the-world-censoring-the-internet-works/2016/05/23/413afe78-fff3-11e5-8bb1-f124a43f84dc_story.html|url-status=live|archive-url=https://web.archive.org/web/20181206113628/https://www.washingtonpost.com/world/asia_pacific/chinas-scary-lesson-to-the-world-censoring-the-internet-works/2016/05/23/413afe78-fff3-11e5-8bb1-f124a43f84dc_story.html|archive-date=6 December 2018|access-date=5 September 2017|newspaper=[[The Washington Post]]}}</ref><ref name="WSJ20152">{{cite news|last1=Chen|first1=Te-Ping|date=28 January 2015|title=China Owns 'Great Firewall,' Credits Censorship With Tech Success|work=WSJ|url=https://blogs.wsj.com/chinarealtime/2015/01/28/china-owns-great-firewall-credits-censorship-with-tech-success/|url-status=live|access-date=2 September 2017|archive-url=https://web.archive.org/web/20171121094528/https://blogs.wsj.com/chinarealtime/2015/01/28/china-owns-great-firewall-credits-censorship-with-tech-success/|archive-date=21 November 2017}}</ref> [[Renren]], [[Youku]], and [[Weibo]].<ref name=":12">{{Cite book |last=Shi |first=Song |title=China and the Internet: Using New Media for Development and Social Change |date=2023 |publisher=[[Rutgers University Press]] |isbn=9781978834736 |location=New Brunswick, NJ}}</ref>{{Rp|page=8}} China has its own version of many foreign web properties, for example: [[Bilibili]] and [[Tencent Video]] (YouTube), [[Weibo]] (Twitter), [[Moments (social networking)|Moments]]<ref>{{cite web |last1=Hoskins |first1=Peter |author2=Fan Wang |title=WeChat: Why does Elon Musk want X to emulate China's everything-app? |url=https://www.bbc.com/news/business-66333633 |website=BBC News |accessdate=2023-07-30 |date=2023-07-29 |archive-date=12 November 2023 |archive-url=https://web.archive.org/web/20231112081132/https://www.bbc.com/news/business-66333633 |url-status=live }}</ref> and [[Qzone]] (Facebook), [[WeChat]] (WhatsApp), [[Ctrip]] (Orbitz and others), and [[Zhihu]]<ref>{{cite news|last1=Millward|first1=Steven|date=12 January 2017|title=China's answer to Quora now worth a billion bucks|work=Tech in Asia|url=https://www.techinasia.com/zhihu-quora-of-china-funding|url-status=live|access-date=4 September 2017|archive-url=https://web.archive.org/web/20170904154318/https://www.techinasia.com/zhihu-quora-of-china-funding|archive-date=4 September 2017}}</ref> ([[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.<ref name="WaPo2017"/>

=== Resistance ===
While the Great Firewall has had an impact on Chinese citizens' ability to use the internet to find information about sensitive topics about the Chinese Communist Party, it has not completely stopped them from doing so. The firewall itself has caused much frustration amongst both individuals and internationally operating companies in China, many of whom have turned to VPNs, speaking in codes,<ref>Lyden, Jacki; Xiao, Qiang (September 7, 2013). [https://www.npr.org/transcripts/220106496 “In China, Avoiding The ‘Great Firewall’ Internet Censors”] {{Webarchive|url=https://web.archive.org/web/20230407050205/https://www.npr.org/transcripts/220106496 |date=7 April 2023 }} NPR Podcasts Transcripts. Retrieved April 20, 2021.</ref> and other methods to retain their access to the international internet.<ref>{{Cite news|last=Li|first=Yan|date=April 6, 2016|title=Chinese Voice Frustration Over 'Great Firewall'; Many Internet users criticize intensified blocking of foreign websites|work=The Wall Street Journal Online|url=https://www.wsj.com/articles/chinese-voice-frustration-over-great-firewall-1459973164|access-date=April 20, 2021|archive-date=20 April 2021|archive-url=https://web.archive.org/web/20210420110757/https://www.wsj.com/articles/chinese-voice-frustration-over-great-firewall-1459973164|url-status=live}}</ref>

==Circumvention==
{{See also|Internet censorship in the People's Republic of China#Evasion{{!}}Internet censorship in the People's Republic of China § Evasion|Internet censorship circumvention}}

=== Methods for bypassing the firewall ===
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. Bypassing the firewall is known as {{transliteration|zh|fānqiáng}} (翻墙, "climb over the wall"), and most circumvention tools combine these two mechanisms:<ref name=Anderson2013>[http://queue.acm.org/detail.cfm?id=2405036 "Splinternet Behind the Great Firewall of China: The Fight Against GFW"] {{Webarchive|url=https://web.archive.org/web/20170920093321/http://queue.acm.org/detail.cfm?id=2405036 |date=2017-09-20 }}, Daniel Anderson, ''Queue'', Association for Computing Machinery (ACM), Vol. 10, No. 11 (29 November 2012), {{doi|10.1145/2390756.2405036}}. Retrieved 11 October 2013.</ref>
* [[Proxy server]]s 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.<ref name=Anderson2013/>
* [[Freegate]], [[Ultrasurf]], [[Psiphon]], and [[Lantern (software)|Lantern]] are free programs designed and experienced with circumventing the China firewall using multiple [[open proxies]].
* [[VPN]]s (virtual private networks) are one of the most popular tools used by Westerners for bypassing censorship technologies.<ref>{{cite web|url=https://www.techinasia.com/5-ways-sneak-chinas-great-firewall|title=Tech in Asia - Connecting Asia's startup ecosystem|website=www.techinasia.com|access-date=2020-01-20|archive-url=https://web.archive.org/web/20200329074408/https://www.techinasia.com/5-ways-sneak-chinas-great-firewall|archive-date=2020-03-29|url-status=live}}</ref> 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.<ref name=Anderson2013/>
* [[Tor (anonymity network)|Tor]] partially can be used in China.<ref name="Anderson2013" /><ref>{{cite web|url=https://www.reddit.com/r/TOR/comments/8cjezx/does_tor_still_work_in_china/|title=r/TOR - Does Tor still work in China?|website=reddit|date=16 April 2018|language=en-US|access-date=2019-11-11|archive-url=https://web.archive.org/web/20190904021327/https://www.reddit.com/r/TOR/comments/8cjezx/does_tor_still_work_in_china/|archive-date=2019-09-04|url-status=live}}</ref> Since 2010, almost all bridges at TorProject.org are blocked through [[#Proxy distribution|proxy distribution]]. Tor still functions in China using Snowflake,<ref>{{cite web | url=https://www.youtube.com/watch?v=YlZZQYLIXe8&t=1400s | title=DEF CON 30 - Roger Dingledine - How Russia is trying to block Tor | website=[[YouTube]] | date=20 October 2022 | access-date=7 April 2023 | archive-date=26 October 2022 | archive-url=https://web.archive.org/web/20221026203753/https://www.youtube.com/watch?v=YlZZQYLIXe8&t=1400s | url-status=live }}</ref> independently published Obfs4 bridges and meek.<ref>{{cite web |url=https://www.usenix.org/system/files/conference/foci18/foci18-paper-dunna.pdf |title=Conference paper |publisher=www.usenix.org |access-date=2020-05-24 |archive-url=https://web.archive.org/web/20191028052521/https://www.usenix.org/system/files/conference/foci18/foci18-paper-dunna.pdf |archive-date=2019-10-28 |url-status=live }}</ref><ref>{{cite web |url=https://www.youtube.com/watch?v=DX46Qv_b7F4&t=949 |title=28c3: How governments have tried to block Tor |publisher=YouTube |date=2011-12-28 |access-date=2020-05-24 |archive-url=https://web.archive.org/web/20200523011126/https://www.youtube.com/watch?v=DX46Qv_b7F4&t=949 |archive-date=2020-05-23 |url-status=live }}</ref><ref>{{Cite web|url=https://trac.torproject.org/projects/tor/ticket/29279|title=Test obfs4 reachability (#29279) · Issues · Legacy / Trac|date=February 2019|access-date=22 July 2020|archive-date=29 October 2020|archive-url=https://web.archive.org/web/20201029124816/https://trac.torproject.org/projects/tor/ticket/29279|url-status=live}}</ref><ref>{{Cite web|url=https://www.youtube.com/watch?v=g6xEfNHkFKY|title=Circumventing Internet Censorship with Tor|date=30 June 2020|accessdate=Dec 3, 2022|via=www.youtube.com|archive-date=3 December 2022|archive-url=https://web.archive.org/web/20221203172133/https://www.youtube.com/watch?v=g6xEfNHkFKY|url-status=live}}</ref>
* [[I2P]] or [[garlic routing]] is useful when properties similar to Tor's anonymity are needed. Due to I2P being much less popular than Tor, it has faced little to no blocking attempts.
In 2017, the Chinese government declared unauthorized VPN services illegal, requiring VPN providers to obtain state approval.<ref>{{Cite news |last=Ye |first=Josh |date=January 2017 |title=China tightens Great Firewall by declaring unauthorized VPN services illegal |work=[[South China Morning Post]] |url=https://www.scmp.com/news/china/policies-politics/article/2064587/chinas-move-clean-vpns-and-strengthen-great-firewall |access-date=April 21, 2021 |archive-date=24 April 2021 |archive-url=https://web.archive.org/web/20210424082112/https://www.scmp.com/news/china/policies-politics/article/2064587/chinas-move-clean-vpns-and-strengthen-great-firewall |url-status=live }}</ref> Although China restricts VPNs, they remain widely used by private individuals.<ref name=":9222">{{Cite book |last=Šebok |first=Filip |title=Contemporary China: a New Superpower? |publisher=[[Routledge]] |year=2023 |isbn=978-1-03-239508-1 |editor-last=Kironska |editor-first=Kristina |chapter=Social Control and Propaganda |editor-last2=Turscanyi |editor-first2=Richard Q.}}</ref>{{Rp|page=109}} [[State-owned enterprises of China|State-owned enterprises]] or state institutions also use VPNs for official work.<ref name=":9222" />{{Rp|page=109}} The Chinese government has authorized several official VPN providers.<ref name=":9222" />{{Rp|page=109}} Those who develop or sell their own VPNs potentially face years in prison.<ref name=":9222" />{{Rp|page=109}}

Non-proxy circumvention strategies include:
* Using [[DNS over HTTPS|encrypted DNS]] may bypass blocking of a few sites including TorProject and all of GitHub, which may be used to obtain further circumvention.<ref>{{cite web|url=http://www.tipsforchina.com/how-to-use-dnscrypt-to-bypass-dns-spoofing-poisoning-in-china.html|title=How to Use DNSCrypt to Prevent DNS Spoofing in China &#124; Tips for China|website=www.tipsforchina.com|date=13 May 2019|access-date=2020-02-17|archive-url=https://web.archive.org/web/20200217221544/https://www.tipsforchina.com/how-to-use-dnscrypt-to-bypass-dns-spoofing-poisoning-in-china.html|archive-date=2020-02-17|url-status=live}}</ref> In 2019 Firefox released an update to make it easy to enable DNS over HTTPS.<ref>{{cite web|url=https://blog.mozilla.org/futurereleases/2019/04/02/dns-over-https-doh-update-recent-testing-results-and-next-steps|title=DNS-over-HTTPS (DoH) Update – Recent Testing Results and Next Steps|first=Selena|last=Deckelmann|website=Future Releases|date=2 April 2019 |access-date=2020-01-20|archive-url=https://web.archive.org/web/20200107031853/https://blog.mozilla.org/futurereleases/2019/04/02/dns-over-https-doh-update-recent-testing-results-and-next-steps/|archive-date=2020-01-07|url-status=live}}</ref> Despite DNS over encryption, the majority of services remain blocked by IP.<ref>{{cite web |url=https://dnsencryption.info/imc19-doe.pdf |title=Archived copy |website=dnsencryption.info |access-date=15 January 2022 |archive-url=https://web.archive.org/web/20201026013416/https://dnsencryption.info/imc19-doe.pdf |archive-date=26 October 2020 |url-status=dead}}</ref>
* Ignoring TCP reset packets sent by the GFW. Distinguishing them by the TTL value (time to live), and not routing any further packets to sites that have triggered blocking behavior.<ref>[http://www.cl.cam.ac.uk/~rnc1/ignoring.pdf "Ignoring the Great Firewall of China"] {{Webarchive|url=https://web.archive.org/web/20170909233123/http://www.cl.cam.ac.uk/~rnc1/ignoring.pdf |date=2017-09-09 }}, Richard Clayton, Steven J. Murdoch, and Robert N. M. Watson, ''PET'06: Proceedings of the 6th international conference on Privacy Enhancing Technologies'', Springer-Verlag (2006), pages 20–35, {{ISBN|3-540-68790-4}}, {{doi|10.1007/11957454_2}}. Retrieved 11 October 2013.</ref>

=== Known blocked methods ===
* The [[OpenVPN]] protocol is detected and blocked. Connections not using symmetric keys or using "tls-auth" are blocked at handshake, and connections using the new "tls-crypt" option are detected and throttled (under 56&nbsp;kbit/s) by the QoS filtering system.{{Citation needed|date=January 2020}}
* [[Generic Routing Encapsulation|GRE]] tunnels and protocols that use GRE (e.g., [[PPTP]]) are blocked.{{Citation needed|date=June 2021}}
* [[Transport Layer Security|TLS]], the Great Firewall can identify the difference between HTTPS TLS and other implementations by inspecting the handshake parameters.<ref>{{cite web |url=https://www.youtube.com/watch?v=3z56andRyCY |title=Defcon 21 - Defeating Internet Censorship with Dust, the Polymorphic Protocol Engine |publisher=YouTube |date=2013-11-16 |access-date=2020-05-24 |archive-url=https://web.archive.org/web/20160707183101/https://www.youtube.com/watch?v=3z56andRyCY |archive-date=2016-07-07 |url-status=live }}</ref><ref>{{cite web |url=https://www.youtube.com/watch?v=QBp6opkcxoc&feature=youtu.be&t=361 |title=32C3 - How the Great Firewall discovers hidden circumvention servers |publisher=YouTube |date=2016-04-24 |access-date=2020-05-24 |archive-date=21 March 2022 |archive-url=https://web.archive.org/web/20220321051525/https://www.youtube.com/watch?v=QBp6opkcxoc&feature=youtu.be&t=361 |url-status=live }}</ref><ref>{{cite web |url=https://tlsfingerprint.io/static/frolov2019.pdf |title=Data |publisher=tlsfingerprint.io |date=2019 |access-date=2020-05-24 |archive-url=https://web.archive.org/web/20190227201210/https://tlsfingerprint.io/static/frolov2019.pdf |archive-date=2019-02-27 |url-status=live }}</ref><ref>{{cite web|url=https://www.youtube.com/watch?v=35l56KjTCb8&feature=youtu.be&t=5315  |archive-url=https://ghostarchive.org/varchive/youtube/20211222/35l56KjTCb8 |archive-date=2021-12-22 |url-status=live|title=Anti-Censorship & Transparency - Roger Dingledine |date=26 October 2010 |publisher=YouTube |access-date=2020-05-24}}{{cbignore}}</ref>

==Outside China==
===Off-target incidents===
In 2010, a [[root name server]] run by [[Netnod]] in China started returning poisoned DNS results to global users, preventing users in [[Chile]] and the U.S. from accessing sites such as Facebook. The server was shut down to stop the poisoning.<ref>{{cite web |last1=McMillan |first1=Robert |title=After DNS problem, Chinese root server is shut down |url=https://www.computerworld.com/article/2755924/after-dns-problem--chinese-root-server-is-shut-down.html |website=Computerworld |language=en |date=26 March 2010 |access-date=28 January 2023 |archive-date=9 April 2023 |archive-url=https://web.archive.org/web/20230409102959/https://www.computerworld.com/article/2755924/after-dns-problem--chinese-root-server-is-shut-down.html |url-status=live }}</ref>

In 2014, two-thirds of China's DNS infrastructure began resolving unrelated domains to 65.49.2.178, an address owned by the US-based [[Freegate|Dynamic Internet Technology, Inc.]], [[Internet anomalies in mainland China in 2014|resulting in widespread internet outage in China]]. No damage to DIT services were reported despite what amounts to an accidental [[DDoS]]. While some sources attribute this incident to GFW's DNS poisoning,<ref>{{cite web |last1=Leyden |first1=John |title=DNS poisoning slams web traffic from millions in China into the wrong hole |url=https://www.theregister.com/2014/01/21/china_dns_poisoning_attack/ |website=www.theregister.com |language=en |access-date=28 January 2023 |archive-date=29 January 2023 |archive-url=https://web.archive.org/web/20230129112348/https://www.theregister.com/2014/01/21/china_dns_poisoning_attack/ |url-status=live }}</ref> others (mostly quoting Chinese sources) speculate this incident was somehow caused by DIT themselves.<ref name=":4">{{Cite web|last=Carsten|first=Paul|title="Massive Internet mishap sparks Great Firewall scrutiny in China"|url=http://uk.reuters.com/article/us-china-internet-idUKBREA0K04T20140122|access-date=22 Jan 2014|website=Reuters|archive-date=8 March 2016|archive-url=https://web.archive.org/web/20160308013801/http://uk.reuters.com/article/us-china-internet-idUKBREA0K04T20140122|url-status=dead}}</ref>

=== Exporting Great Firewall technology ===
[[Reporters Without Borders]] suspects that countries such as [[Censorship in Cuba|Cuba]], [[Censorship in Iran|Iran]],<ref>{{Cite web|title=Iran To Work With China To Create National Internet System|url=https://www.rferl.org/a/iran-china-national-internet-system-censorship/30820857.html|access-date=2020-09-30|website=www.rferl.org|archive-date=30 September 2020|archive-url=https://web.archive.org/web/20200930031242/https://www.rferl.org/amp/iran-china-national-internet-system-censorship/30820857.html|url-status=live |last1=Esfandiari |first1=Golnaz |date=4 September 2020 }}</ref> [[Censorship in Vietnam|Vietnam]], [[Censorship in Zimbabwe|Zimbabwe]], and [[Censorship in Belarus|Belarus]] have obtained surveillance technology from China, although the censorship in these countries is less stringent than in China.<ref name="cubaonline">{{cite web|year=2006|title=Going online in Cuba: Internet under surveillance|url=http://www.rsf.org/IMG/pdf/rapport_gb_md_1.pdf|url-status=dead|archive-url=https://web.archive.org/web/20090303221407/http://www.rsf.org/IMG/pdf/rapport_gb_md_1.pdf|archive-date=3 March 2009|publisher=Reporters Without Borders|df=dmy}}</ref>

Since at least 2015, the Russian [[Federal Service for Supervision of Communications, Information Technology and Mass Media|Roskomnadzor]] agency collaborates with Chinese Great Firewall security officials in implementing its data retention and filtering infrastructure.<ref>{{Cite news|last1=Soldatov|first1=Andrei|last2=Borogan|first2=Irina|date=2016-11-29|title=Putin brings China's Great Firewall to Russia in cybersecurity pact|language=en-GB|work=The Guardian|url=https://www.theguardian.com/world/2016/nov/29/putin-china-internet-great-firewall-russia-cybersecurity-pact|access-date=2017-07-04|issn=0261-3077|archive-date=6 July 2021|archive-url=https://web.archive.org/web/20210706183836/https://www.theguardian.com/world/2016/nov/29/putin-china-internet-great-firewall-russia-cybersecurity-pact|url-status=live}}</ref><ref name="eurozine">{{cite news|date=2017-02-21|title=China: The architect of Putin's firewall|publisher=[[Eurozine]]|url=https://www.eurozine.com/china-the-architect-of-putins-firewall/|access-date=2019-12-10|archive-date=3 May 2021|archive-url=https://web.archive.org/web/20210503194417/https://www.eurozine.com/china-the-architect-of-putins-firewall/|url-status=live}}</ref><ref>{{cite news|date=2016-04-29|title=Russia's chief internet censor enlists China's know-how|publisher=[[Financial Times]]|url=https://www.ft.com/content/08564d74-0bbf-11e6-9456-444ab5211a2f |archive-url=https://ghostarchive.org/archive/20221211/https://www.ft.com/content/08564d74-0bbf-11e6-9456-444ab5211a2f |archive-date=2022-12-11 |url-access=subscription|access-date=2019-12-10}}</ref> During his visit to Beijing in June 2016, Vladimir Putin signed a joint communiqué with [[Xi Jinping]] on information space, followed by Russia's National Forum for Information Security in October hosted by [[Fang Binxing]], the architect of the Chinese Great Firewall.<ref name="eurozine"/>

Especially since the [[2022 Russian invasion of Ukraine]], in order to enforce the [[Russian 2022 war censorship laws|war censorship law]], Russian authorities were making an internet surveillance system akin to Chinese Great Firewall.<ref>{{cite web|url=https://apnews.com/article/russia-internet-censorship-efforts-reveal-shortcomings-c2156ead73e1c33cb9357fb954f958f8|title=War censorship exposes Putin's leaky internet controls|website=[[Associated Press]]|date=March 14, 2022|access-date=18 December 2022|archive-date=21 May 2023|archive-url=https://web.archive.org/web/20230521183313/https://apnews.com/article/russia-internet-censorship-efforts-reveal-shortcomings-c2156ead73e1c33cb9357fb954f958f8|url-status=live}}</ref>

=== Opposition ===
Critics have argued that if other large 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.<ref name="The Great Firewall of China">{{cite news|title=The Great Firewall of China|url=https://www.bloomberg.com/quicktake/great-firewall-of-china|url-status=live|archive-url=https://web.archive.org/web/20180331034226/https://www.bloomberg.com/quicktake/great-firewall-of-china|archive-date=31 March 2018|access-date=2 April 2018|website=Bloomberg}}</ref>

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."<ref>{{cite news|last1=Barfield|first1=Claude|title=China's Internet censorship: A WTO challenge is long overdue|url=https://www.aei.org/publication/chinas-internet-censorship-a-wto-challenge-is-long-overdue/|access-date=26 January 2017|publisher=TechPolicyDaily.com|date=29 April 2016|archive-url=https://web.archive.org/web/20160430114152/http://www.aei.org/publication/chinas-internet-censorship-a-wto-challenge-is-long-overdue/|archive-date=30 April 2016|url-status=live}}</ref> 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.<ref>{{cite news|last1=Barfield|first1=Claude|title=China bans 8 of the world's top 25 websites? There's still more to the digital trade problem.|url=http://www.aei.org/publication/china-bans-8-of-top-25-websites-still-more-digital-trade-problem/|access-date=26 January 2017|agency=American Enterprise Institute|date=25 January 2017|archive-url=https://web.archive.org/web/20170126092521/http://www.aei.org/publication/china-bans-8-of-top-25-websites-still-more-digital-trade-problem/|archive-date=26 January 2017|url-status=live}}</ref> Eight 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.<ref>{{cite news|last1=Martina|first1=Paul|title=U.S. says China internet censorship a burden for businesses|url=https://www.reuters.com/article/us-usa-china-trade-internet/u-s-says-china-internet-censorship-a-burden-for-businesses-idUSKCN0X50RD|newspaper=Reuters|agency=Reuters|access-date=23 March 2018|date=8 April 2016|archive-url=https://web.archive.org/web/20180402225919/https://www.reuters.com/article/us-usa-china-trade-internet/u-s-says-china-internet-censorship-a-burden-for-businesses-idUSKCN0X50RD|archive-date=2 April 2018|url-status=live}}</ref>

According to [[Stephen Peter Rosen|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:

{{blockquote|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 China, 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.<ref>{{cite episode |url=https://conversationswithbillkristol.org/video/stephen-rosen-ii/ |first=Bill |last=Kristol |author-link=Bill Kristol |title=Stephen Rosen interview |date=30 November 2018 |series=Conversations With Bill Kristol |transcript-url=https://conversationswithbillkristol.org/transcript/stephen-rosen-ii-transcript/ |transcript=Transcript |access-date=26 October 2019 |archive-url=https://web.archive.org/web/20200325014729/https://conversationswithbillkristol.org/video/stephen-rosen-ii/ |archive-date=25 March 2020 |url-status=live }}</ref>}}

== See also ==
{{Portal|China|Internet}}
{{div-col}}
* [[List of websites blocked in mainland China]]
* [[Bamboo Curtain]]
* [[Censorship in China]]
* [[Wikipedia blocked by China|Censorship of Wikipedia by China]]
* [[Cipher|Cypher]]
* [[Great Cannon]] — A [[denial-of-service attack|distributed denial-of-service]] attack tool co-located with the Great Firewall.
* [[GreatFire]] — An organization monitoring and providing apps, 12 websites, code, tests and tools related to the Great Firewall
* [[Green Dam Youth Escort]]
* [[Great Wall of Sand]]
* [[International Freedom of Expression Exchange]] – monitors<ref>{{Cite web |title=China |url=http://www.ifex.org/en/content/view/full/147 |url-status=dead |archive-url=https://web.archive.org/web/20050423180620/http://www.ifex.org/en/content/view/full/147 |archive-date=April 23, 2005 |website=[[IFEX (organization)|IFEX]]}}</ref>
* [[Internet censorship circumvention]]
* [[Media of China]]
* [[Politics of China]]
* [[Splinternet]]
* ''[[Who Controls the Internet?]]''
{{div-col-end}}

==Notes==
{{reflist|group=nb}}

==References==
{{reflist}}

==Further reading==
{{Library resources box}}

* {{Cite book |last=Griffiths |first=James T. |url=https://books.google.com/books?id=S72rDwAAQBAJ |title=The Great Firewall of China: How to Build and Control an Alternative Version of the Internet |date=2019 |publisher=[[Zed Books]] |isbn=978-1-78699-535-3 |location=London}}
* {{Cite journal |last=Nilekani |first=Nandan |author-link=Nandan Nilekani |date=September–October 2018 |title=Data to the People: Indias Inclusive Internet |journal=[[Foreign Affairs]] |volume=97 |issue=5 |pages=19–26 |issn=0015-7120 |jstor=44823909}}
* {{Cite journal |last=Segal |first=Adam |author-link=Adam Segal |date=September–October 2018 |title=When China Rules the Web: Technology in Service of the State |journal=[[Foreign Affairs]] |volume=97 |issue=5 |pages=10-14, 16-18 |issn=0015-7120 |jstor=44823908}}

== External links ==
* {{Commons category-inline}}
* {{Wiktionary-inline|firewall}}
* {{Wikiquote-inline}}

{{Clear}}
{{Censorship in China}}
{{Internet censorship circumvention technologies}}

[[Category:Internet censorship in China]]
[[Category:Firewall software]]