How the Great Firewall of China Affects Performance of Websites Outside of China

The Great Firewall of China, or as it’s officially called, the Golden Shield Project, is an internet censorship project to block people from accessing specific foreign websites. It is the world’s most advanced and extensive Internet censorship program. This project implements multiple techniques and tactics to censor China’s internet and controls the internet gateways to analyze, filter, and manipulate the internet traffic between inside and outside of China.

The reasons behind this internet censorship are many, but most of them are for favoring the Communist Party’s internet policy for political gain. By doing this, China is also able to force people to use Chinese alternatives for websites.  For example, WeChat and Weibo, which further allows the government to control the content being posted on such platforms.

Now, for a deeper understanding, the censorship by the Great Firewall of China is not just blocking individual foreign websites and service providers but extensively scanning URLs and webpages for blacklisted keywords, among other neat technical tricks to control the internet traffic of China.


The How and What of The Great Firewall of China

The Great Firewall of China is something that isn’t straight forward to decode with transparent policies. It’s a complex architecture with multiple layers of controlled tricks to block access to websites.  It’s designed in such a way that you won’t even notice if the website has been blocked.  For example, if you land on a website that is blocked, you won’t see any warning or information regarding that.  Instead, you will encounter forever loading and other messages like timeout, connection error, network problem, etc. This makes it very hard to know what happened and you can only guess what the actual issue is.  Let’s take a look at different methodologies incorporated in the Great Firewall of China.


DNS Poisoning/Spoofing.  Any website request initially goes to the DNS server to fetch the IP address of the website and accesses it on the responded address. If the response from the DNS is incorrect, you won’t be able to access the website. If the DNS caches are manipulated to contain wrong IP addresses, it’s called DNS poisoning. China does exactly that for blocking commonly known websites.

Blocking IP Access. This is a widely known and commonly used technique, also used by Great Firewall of China, to prevent access to several IP addresses. Even if you try to access the website by directly using the correct IP address of a website, if that IP is blocked by using this technique, you won’t be able to access it (especially in 2022).

URLs Analysis and Filtering. China’s firewall can block the entire website or selective webpages based on the requested URL scan for blocked keywords.  As a popular example before china completely blocked Wikipedia in all languages, Wikipedia was accessible from China, but the Wikipedia article regarding internet censorship in China was not accessible due to the use of blocking “Internet censorship” keyword.

Deep Packet Inspection. Deep packet inspection (DPI) techniques are also deployed by China’s Great Firewall to extensively inspect incoming and outgoing unencrypted network traffic for packets, filtering and blocking data packets that contain sensitive information that is censored by China.

Resetting Connections. The Great Firewall of China also uses the trick to reset connections between two communicating devices/servers, as long as the transmitted data is qualified as sensitive data. This essentially means that after blocking the data packets, the firewall can also reset the client-server connection for a certain time period.

Blocking VPNs.  What do you do when a website is blocked? You try to access it using an encrypted VPN. Well, the Great Firewall of China is continuously learning the evolving attributes of a VPN traffic to terminate known VPNs, as well as new VPNs.

Legal Corporate Censorship. As you might have guessed already, to orchestrate the level of censorship that is done by the Great Firewall of China, Chinese companies are also bounded by the law to not distribute sensitive information that is censored. And if they do so, knowingly or unknowingly, a heavy fine and punishment are imposed.


What Does This Mean for Your Websites and Applications?

As we have said earlier, how China polices the internet traffic is not completely transparent, but you now have a pretty good idea of what the Great Firewall of China is capable of. So, what does this mean for your business? Let’s take a look at problems your websites or applications will face when accessed from China.

  • If you have any sensitive information anywhere on your website or application that you don’t know about, you will be blocked at least partially, if not completely.
  • If you’re using any third-party services that are blocked in China, even including open-source libraries from blocked vendors, your websites or applications will fail to function properly, or even be inaccessible from China.
  • If you run ads from Google Adsense, or any other blocked companies, along with banned advertisements in China, they won’t appear on your page and your websites or applications may also face access restrictions.
  • Since traffic to your website or application will go through intensive inspections, you will face constant website speed and performance issues.
  • China has a huge population, so your website or application will face a lot of stress during peak hours, such as mornings and afternoons, which will cause performance issues.


Again, as the censorship is not transparent, it is hard to predict all the sorts of problems your websites or applications will encounter in China. So, let’s see how you can best approach and strategize to ensure your websites and applications function properly in China.


How to Get Around the Great Firewall of China:  Approaches and Solutions

Internet and Information are free birds by origin. You can try your level best to censor the internet and hold back the information, but you can’t block everything.  Such is the case with the Great Firewall of China. As censorship is evolving, so are the approaches and tools to encounter it at the same time.  Here is how you can address the issues caused by censorship with available tools and techniques.


  • Monitor your website speed from China.  With a large population and censorship, websites behave differently in china, using a monitoring tool that gives you the ability to monitor your website speed from within the china so that you can identify and optimize for it.
  • Monitor third-party services from China.  As your website might be perfectly fine but the issues with third-party services can bog down your website, so you need to monitor them thoroughly from inside china with a good web service monitoring tool.
  • Pair with a local CDN.  For increasing website speed and reliable content distribution, you can opt for a local Chinese CDN such as Alibaba Cloud or Baidu cloud, for example.


In Conclusion:  Monitoring Website Performance from China

To sum it up, if you’re entering the Chinese market and have identified a substantial user base there, it’s critical that you continually monitor your website performance from within China and identify ongoing performance problems. Monitoring from outside the Great Firewall of China, from external locations, isn’t enough.  Choose a monitoring solution with the capability of testing you website from multiple geolocations, including China.  Dotcom-Monitor provides a number of free online network performance tools , including a Great Firewall Test to check the performance of your websites, applications, servers, and more, from behind the Great Firewall of China.

Or for access to more advanced monitoring capabilities, try the full Dotcom-Monitor platform for free.


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