Great Firewall

Based on Wikipedia: Great Firewall

Imagine trying to visit Google and finding nothing—not an error message, not a slow-loading page, just a connection that quietly dies. Now imagine this happening for Facebook, Twitter, Wikipedia, and thousands of other websites you've probably used today without a second thought. For nearly a billion internet users in China, this isn't a hypothetical scenario. It's Tuesday.

The system responsible for this digital erasure is known as the Great Firewall, a name that playfully mashes together "firewall"—the computer security term for a system that blocks unauthorized network traffic—with the Great Wall of China, that ancient monument to ambitious barrier-building. An Australian scholar named Geremie Barmé coined the phrase in 1997, and it stuck.

How the Wall Works

At its core, the Great Firewall performs a remarkably simple task: it reads the data flowing in and out of China and decides what to let through.

When you browse the internet, your computer breaks your requests into small packets of data using something called the Transmission Control Protocol, or TCP. Think of these packets like postcards traveling through the mail system. The Great Firewall is essentially a nosy postal worker who reads every postcard, looking for certain words.

If your postcards contain the wrong words—political terms the government considers sensitive, names of banned organizations, references to historical events Beijing would rather forget—the postal worker doesn't just throw away that postcard. They throw away all your postcards. Your connection closes. If you try again from the same computer, more of your traffic gets blocked. The system learns.

But keyword filtering is just one tool in a larger arsenal. The Firewall also manipulates the Domain Name System, the internet's phone book that translates human-readable addresses like "google.com" into the numerical addresses computers actually use. When you type a blocked URL into your browser, the Firewall can simply lie about where that address points—or pretend the address doesn't exist at all.

Then there's deep packet inspection, a more sophisticated technique where the Firewall doesn't just read the postcards but examines how they're packaged, looking for telltale signs of encrypted traffic that might be trying to sneak past censorship. When it spots suspicious patterns, it can reset connections or simply slow them to a crawl—technically allowing access while making the experience so frustrating that most users give up.

The Philosophy of Flies

To understand why China built this system, you need to understand a metaphor about windows and insects.

In the early 1980s, Deng Xiaoping—the leader who opened China to market economics after decades of Maoist isolation—liked to say: "If you open the window, both fresh air and flies will be blown in." The fresh air was foreign investment, technology, and economic growth. The flies were foreign ideas about politics, religion, and individual rights.

Deng's economic reforms represented a delicate bargain: China would embrace capitalism's wealth-generating machinery while keeping the Chinese Communist Party firmly in control. The party would deliver prosperity; citizens would not question the party's monopoly on political power. This arrangement required keeping certain kinds of information—the flies—from circulating too freely.

When the internet arrived in China in 1994, it looked like a tool that could serve the "socialist market economy." Online commerce, electronic communication, information sharing—all useful for modernization. But it also looked like the biggest window anyone had ever opened, with flies pouring in from every direction.

Building the Barrier

The legal foundation came first. In 1996, Premier Li Peng signed regulations requiring all internet connections leaving China to pass through government-controlled gateways. No private channels to the outside world. No digital escape routes. Article 6 of State Council Order Number 195 made this explicit: all international connections "must use the international entry and exit channels provided by the Ministry of Posts and Telecommunications." Anyone caught building their own connections would face punishment.

The following year, 1997, brought comprehensive regulations from the Ministry of Public Security. These rules prohibited using the internet to harm national security, disclose state secrets, or "injure the interests of the state or society." They banned content that might incite resistance to the constitution, undermine national unity, or "distort the truth." The language was deliberately vague. Vague laws are flexible laws, adaptable to whatever the party needs them to prohibit.

China's legislature, the National People's Congress, passed a cybercrime law that same year. Some Chinese judges complained that it was too vague to enforce effectively. The Congress replied that this was intentional—the law was meant to be "flexible" for future interpretation. In practice, this meant the State Council, the government's administrative arm, could decide what counted as a crime without bothering with legislative process.

The technical infrastructure came next. In 1998, the same year the China Democracy Party was banned and its members imprisoned, construction began on what would become known as the Golden Shield Project—a vast surveillance and filtering system that would take eight years to complete. The hardware came largely from American companies, including Cisco Systems, which supplied the networking equipment that would power Chinese censorship for years to come.

The Man Called "Father"

Every massive infrastructure project needs an architect, and the Great Firewall found its in Fang Binxing. A computer scientist who would eventually become president of Beijing University of Posts and Telecommunications, Fang earned the nickname "Father of China's Great Firewall" for his work designing the system's core architecture.

The title brought him no love from Chinese internet users. When Fang opened a social media account on Weibo, China's Twitter equivalent, he was buried under thousands of angry comments before his account was quickly deleted. In 2011, someone threw a shoe at him during a university lecture—a gesture of extreme disrespect in Chinese culture. Another attacker hit him with eggs.

Fang reportedly needed a Virtual Private Network, or VPN—a tool for bypassing the very firewall he built—to access certain technical resources for his work. The irony was not lost on his critics.

What Gets Blocked

A State Council document from September 2000 lists nine categories of forbidden content. The list reads like a catalog of government anxieties:

Content opposing the constitution's basic principles. Content jeopardizing national security or divulging state secrets. Content harming the nation's honor. Content inciting ethnic hatred or disrupting ethnic solidarity. Content disrupting religious policies or propagating "evil cults and feudal superstitions." Content spreading rumors or disturbing social stability. Content spreading obscenity, pornography, gambling, violence, or terrorism. Content insulting or defaming individuals. And, in case anything was missed, content "prohibited by law or administrative rules."

In practice, this means blocking Google because it won't filter search results to Beijing's satisfaction. It means blocking Facebook and Twitter because they allow uncontrolled discussion. It means blocking Wikipedia—first the Chinese-language version in 2015, then all languages by 2019—because anyone can edit it, and who knows what they might write.

It also means blocking news about topics the party considers sensitive: the Tiananmen Square massacre of 1989, the Tibetan independence movement, the pro-democracy protests in Hong Kong, the spiritual movement Falun Gong, the treatment of Uyghur Muslims in Xinjiang, and even the names of top leaders like Xi Jinping when combined with terms that might be unflattering.

The Economics of Isolation

Blocking foreign websites created opportunities for domestic alternatives. When Google Search became unreliable, users turned to Baidu. When YouTube was blocked, Youku and Bilibili filled the gap. When Facebook and Twitter disappeared, WeChat and Weibo took over. When Amazon and eBay struggled with access issues, Alibaba and JD.com flourished.

This wasn't entirely accidental. Economic protectionism is one of the explicit rationales for the Great Firewall. Chinese companies operating under Chinese regulations are easier to control than foreign ones. When Beijing tells Weibo to censor certain hashtags, Weibo complies. When it told Apple to remove a news app that covered Hong Kong's protests, Apple complied too—but such compliance from foreign companies is never guaranteed in the way domestic obedience is.

The result is a parallel internet ecosystem worth hundreds of billions of dollars, dominated by Chinese tech giants that have grown enormous precisely because their foreign competitors can't effectively reach Chinese consumers. Some argue this was always the point—that censorship and industrial policy are two faces of the same coin.

The Cat and Mouse Game

For years, technologically savvy Chinese users have found ways over, under, and through the wall. Virtual Private Networks encrypt traffic and route it through servers outside China, masking both content and destination. Proxy servers act as intermediaries, fetching blocked content on behalf of users. The Tor network, designed to provide anonymity, bounces traffic through multiple relays to obscure its origin and destination.

The Great Firewall has evolved to counter each technique. It maintains lists of known VPN and Tor servers, blocking connections to them. It uses deep packet inspection to identify VPN traffic even when the destination server is unknown. Most cleverly, it employs something called active probing: when the system detects suspicious traffic—say, a connection that might be a VPN—it sends its own probe to the destination server to verify whether it's actually a VPN server, then adds confirmed VPNs to the blacklist.

This is remarkably sophisticated. Imagine border guards who, when they suspect someone might be receiving smuggled goods, secretly pose as smugglers themselves to test whether the supplier is real. Then they arrest anyone who confirmed suppliers.

VPN providers have responded with obfuscation protocols that disguise VPN traffic as ordinary web browsing. The Firewall has responded by getting better at detecting disguises. The users have responded by developing new disguises. And so it continues, an endless arms race between those who build walls and those who build ladders.

The Scale of Surveillance

The Golden Shield Project, which operates much of the Firewall's infrastructure, employs an estimated 30,000 to 50,000 internet police. These aren't all hackers hunched over keyboards looking for dissidents. Many are regular officers dispatched when the system flags concerning content—someone posting about organizing a protest, someone sharing too much about a sensitive topic, someone who keeps trying to access forbidden information.

Internet cafes, once hugely popular in China as they were across the developing world, became surveillance nodes. Regulations required them to log every customer's identity and browsing activity. Those logs could be confiscated by police at any time. Minors—anyone under 18—were officially banned from internet cafes, though this rule was widely ignored, spawning underground "black web bars" that operated outside the law.

Private companies became enforcement arms of the state. Internet service providers must block content on government lists. Social media platforms must monitor their own users and delete forbidden posts, often within minutes of posting. Search engines must filter results. App stores must reject applications that facilitate circumvention. The Firewall isn't just a government project—it's a mandate that conscripts the entire Chinese internet industry into censorship.

The View From Inside

The official Chinese position is called "internet sovereignty"—the idea that the internet inside China is part of China's territory and subject to Chinese law, just like the physical land. From this perspective, the Great Firewall isn't censorship but governance. Just as China controls what can be built on Chinese soil, it controls what can be transmitted through Chinese networks.

This view rejects the idea, popular among Western technology enthusiasts, that the internet is inherently borderless and free. Borders exist, Beijing argues. They've always existed. The internet just needs proper gates and guards.

Supporters argue that the Firewall protects Chinese society from "spiritual pollution"—Western values and ideas that could destabilize a country of 1.4 billion people. They point to social unrest in other countries that organized through social media, from Arab Spring uprisings to various color revolutions, as evidence of what unfettered internet access can unleash.

Critics, of course, see it differently. They see a system designed to prevent Chinese citizens from learning about their own history, comparing their government to others, or organizing to demand change. They see a population denied access to the same information available to people in most other countries. They see a trade-off where economic growth was purchased at the cost of political freedom.

The Holes in the Wall

The Great Firewall has never been perfect. Researchers have found that it doesn't aim to block 100% of sensitive content—instead, it flags content, warns users, and encourages self-censorship. Most people, when their connection fails mysteriously, don't investigate further. They assume the site is down, or their internet is slow, or they mistyped the address. They move on. The Firewall doesn't need to catch everything; it just needs to catch enough.

VPNs remain available to those determined enough to find them, though their reliability fluctuates with political conditions—during sensitive anniversaries or major party meetings, circumvention becomes noticeably harder. Many businesses, including foreign companies operating in China, use VPNs openly for legitimate work purposes. The government tolerates this gray area while maintaining the power to crack down whenever it chooses.

The system also operates unevenly across China's vast geography. Local governments can run their own supplementary filters. What's accessible in cosmopolitan Shanghai might be blocked in more conservative Henan Province. The Firewall is less a single wall than a complex system of overlapping barriers, each with different heights and different holes.

Special Regions, Special Rules

Hong Kong and Macau, the "Special Administrative Regions" that operate under the "one country, two systems" framework, officially exist outside the Great Firewall. Their separate legal systems guarantee freedoms—including internet freedom—that don't exist on the mainland. Residents of Hong Kong can browse Google, check Facebook, and read whatever Wikipedia articles they like.

But this exception has eroded. After pro-democracy protests swept Hong Kong in 2019 and 2020, Beijing imposed a National Security Law that has been used to block websites documenting the demonstrations. The U.S. State Department has reported that central government authorities closely monitor internet use in both regions. The wall hasn't technically expanded to cover Hong Kong, but Hong Kong has begun building walls of its own.

The Pressure on Outsiders

The Great Firewall shapes behavior far beyond China's borders. Foreign companies face a choice: comply with Chinese content requirements and access a market of nearly a billion internet users, or refuse and be locked out entirely.

Google famously chose to leave China in 2010 rather than continue filtering search results—though it later developed a censored search engine called Project Dragonfly that was abandoned after employee protests. Apple chose to stay, removing apps that Beijing disapproved of, including the Quartz news app after it covered Hong Kong protests. LinkedIn, Microsoft's professional network, censored content to remain in China before eventually shutting down its Chinese service in 2021.

The firewall also affects global platforms when Chinese users are involved. After artist and activist Ai Weiwei was arrested in 2011, search results for his name were modified. Companies have been pressured to remove content that Beijing finds objectionable even when that content is hosted outside China and intended for non-Chinese audiences.

The Curious Subculture Behind the Wall

Living behind the Great Firewall has created its own peculiar information ecosystem. Chinese internet users have developed sophisticated ways to discuss forbidden topics through euphemism, wordplay, and coded references that evade keyword filters. They've created a rich culture of internet memes that satirize censorship while staying just barely within bounds.

But there are costs to this information environment. When most of the global internet is inaccessible, a "peculiarly domestic version of the world" circulates instead—one where information arrives secondhand, filtered through state media or the telephone game of social media posts. Media literacy varies wildly. Red lines are sensed rather than explicitly stated, encouraging self-censorship that often goes further than authorities actually require.

This has given rise to what observers call China's "world affairs fandom"—communities of people who follow international events with passionate intensity, but through the distorted lens of available information. They debate global politics in spaces where much of the relevant information is simply absent, developing confident opinions built on incomplete foundations.

Looking Forward

The Great Firewall has been operational, in some form, for over a quarter century. It has grown more sophisticated, more comprehensive, and more effective with each passing year. What began as keyword filtering has evolved into a system of deep packet inspection, active probing, and machine learning. The gap between the Chinese internet and the global internet has widened, not narrowed.

At the same time, the Firewall has never fully achieved its goal of hermetic information control. VPNs persist. Clever netizens find workarounds. News seeps through, even if only to small numbers of determined seekers. The wall is very good at shaping what most people see most of the time—but it has never been able to control everything.

Perhaps that's the point. One scholar's analysis suggests the Firewall isn't really designed for perfect control but for "raising the cost" of accessing forbidden information. It doesn't need to stop everyone, just enough people. It doesn't need to block everything, just create enough friction that most users stay within approved boundaries.

The flies keep coming in through the window. The swatters keep swinging. And nearly a billion people navigate daily life in an internet that looks nothing like the one the rest of the world uses—searching on Baidu instead of Google, messaging on WeChat instead of WhatsApp, sharing on Weibo instead of Twitter, and wondering, perhaps occasionally, what they might be missing.