The Great Firewall of China (GFW) is a nickname given to China’s internet censorship system, which operates through state legislation and internet filtering technologies.
Since its inception in 2003, the GFW has empowered Chinese authorities to monitor and restrict internet access in mainland China.
The Great Firewall censors the internet by imposing restrictions, slowing down connections, or outright blocking access to specific websites, applications, and online services.
Unlike internet censorship in other countries, China’s Great Firewall has been built into the country’s internet infrastructure since its earliest days, making it a fundamental component of its online governance.
The Great Firewall uses a combination of five methods to block websites and apps:
- IP Blocking: Preventing access to specific websites by blocking the IP addresses of their servers.
- DNS Spoofing: Redirecting traffic from targeted websites to alternate destinations, effectively blocking access.
- Keyword and URL Filtering: Scanning website content and URLs for specific terms deemed sensitive or prohibited.
- Deep Packet Inspection (DPI): Analyzing the structure and content of data packets to identify VPN traffic, proxy connections, and banned services, without needing to decrypt them. Since 2023, the GFW has used machine learning-based DPI trained on millions of real traffic samples, allowing it to detect VPN usage from statistical patterns alone.
- Active Probing: When DPI flags a suspicious connection, the GFW sends test traffic to the suspected server to confirm whether it’s a VPN. Servers that respond like a VPN are blocked, which is why a VPN may work initially, but suddenly fail minutes later.
The GFW’s operations are complex and constantly evolving, with the Chinese Communist Party maintaining a high level of secrecy regarding how internet censorship functions within the country.
By combining these technologies and continuously upgrading its infrastructure, China has established the most sophisticated and dynamic system of online censorship in the world.
Does the Great Firewall Block Every VPN?
While China’s Great Firewall actively blocks VPN connections, it can’t block all VPNs.
The Chinese government has been blocking VPNs to some degree since 2011, with intensified measures taken since 2022. Many popular VPNs — including NordVPN and Proton VPN — have become unusable in China as a result.
Even VPNs with obfuscation features can fall victim to the GFW’s censorship, particularly those relying on older scrambling techniques that produce random-looking traffic.
Modern ML-based DPI actively flags high-entropy traffic as suspicious precisely because legitimate internet traffic has recognizable patterns.
During times of heightened political sensitivity — such as the anniversary of June 4 — the Chinese government intensifies its crackdowns, making access to blocked websites significantly more difficult.
However, reliable VPN providers like Astrill and Hide.me typically find workable solutions quickly.
How Do the Best VPNs for China Beat the Great Firewall?
The most effective VPNs evade the GFW using mimicry-based obfuscation: instead of making traffic look like meaningless noise, they make it look like something real and trusted, like Chrome connecting to a major tech company’s website.
A censor can’t block that without breaking normal internet access for everyone. This is why newer protocols like VLESS + REALITY (which borrows the TLS handshake of a legitimate, widely-visited website) are far more effective than older scrambling methods, like obfs4proxy.
Crucially, the best obfuscation tools also handle active probing correctly: when the GFW sends test traffic to a suspected VPN server, the server responds with an innocent-looking web page rather than a VPN handshake.
Without passing these active probing tests, even technically strong obfuscation tools will get quickly burned.
Despite these advances, the GFW still manages to block many VPN servers and blacklisting their IP addresses.
Can You Beat the Great Firewall without a VPN?
There are other circumvention tools that can unblock websites in China, but they’re generally less reliable and offer weaker privacy protections than a good VPN.
Here are five circumvention tools that can work in China:
- Proxies (Shadowsocks): Shadowsocks was once the go-to circumvention tool in China, but it’s now detected with over 90% accuracy by the GFW’s machine learning systems. It remains more useful in countries with less sophisticated censorship, but should not be relied upon in China.
- VLESS + REALITY (self-hosted): The most technically advanced option currently available. It borrows the TLS identity of a real, trusted website, making it extremely difficult to block without collateral damage. Requires technical knowledge to configure using tools like 3X-UI — it’s not available as a consumer app.
- Tor with Pluggable Transports: Tor can work in China when used with its Snowflake pluggable transport, which is more reliable than the older obfs4 bridge. However, Tor is significantly slower than a VPN and is best suited for high-anonymity, low-bandwidth use rather than everyday browsing.
- Lantern: An open-source peer-to-peer tool funded by the US government that routes your traffic through volunteers in less-restricted countries. It does not provide anonymity, as your activity is visible to the volunteer relaying your connection.
- Mirror Websites: Some blocked websites publish mirrored copies at alternative addresses. These are easy to use but temporary — mirrors are frequently discovered and blocked by the GFW — and offer no privacy protection.
