The Great Firewall of China, officially known as the Golden Shield project, uses a variety of methods to block foreign websites that the Chinese government doesn’t like. The Chinese government doesn’t publish a list of blocked sites, so it’s not easy for foreigners to tell if their website is visible in China or not. However, there are several web-based tools that can quickly check for you.

The Great Firewall of China has several different ways of blocking websites, so your website’s availability may change over time. If you have a front-page report about Tiananmen Square, you might find your website blocked, only to find it unblocked after the report vanishes from your front page. Another website might have had its DNS records tampered with or might see any connections ended by the firewall itself, no matter what the website’s current content is.

Great Firewall Of China

In spite of its name, the Great Firewall’s policies can be patchwork and inconsistently applied. Websites blocked in one region may not be blocked in another region. Great Firewall Of China is the quickest way to check your website’s availability at different locations in China.

Enter a website address and the service will send it to five different servers in China. Each server tries to access the website and shows a success or failure message.

It’s simple and quick, but this service has some drawbacks. You can only test homepages and not individual subpages. When I tried to specify a subpage on a website, I received an error message. The service also only checks if a website responds – the Great Firewall could re-route website requests to another web server and you’d be none the wiser.

WebsitePulse

WebsitePulse is useful because it lets you check specific subpages. The Great Firewall doesn’t only block websites, it also filters individual pages based on forbidden words and phrases in their URLs or content. WebsitePulse also offers different regions of China. Both Great Firewall Of China and WebsitePulse can test from Beijing, but the other locations are different.

Plug in a webpage address and you can see whether or not it’s accessible. WebsitePulse can only check one location in China at a time.

The English Wikipedia looks available. We’d get the same results if we tested it on Great Firewall Of China.

Further investigation reveals that some parts of the website are being blocked. Here, the Wikipedia page on the Great Firewall itself is inaccessible. Note how it says “Failure in Receiving Network Data” instead of providing a clear “Blocked” message. The Great Firewall does not inform users when it blocks a website; blocked requests just appear as network errors. The results from Seattle help clarify this – Wikipedia itself isn’t down; it just appears down in China when you access this page.

ViewDNS

ViewDNS checks for DNS poisoning. One tactic the Great Firewall uses is redirecting website addresses to other websites. For example, an Internet user in China might be redirected to Baidu, a search engine based in China, when they try to access Google. This subterfuge will show up as your website loading successfully in other tools. Another tactic is just changing a website’s DNS entry and pointing it nowhere – the website won’t load at all.

Enter an website’s address to see the expected IP address and whether it matches with the IP address returned from DNS servers in China. ViewDNS also tries to access the website in different regions and informs you whether or not it was successful.

Note how each different region points Facebook’s website to a different IP address — none of them load anything, but this prevents access to Facebook. It’s also interesting that the server in Inner Mongolia received a timeout rather than an incorrect IP address — is this because Facebook is being blocked differently in that region, or because of a legitimate network problem? That’s the thing about the Great Firewall: it’s hard to tell whether the firewall is interfering or whether there’s an actual network problem.

Bypassing The Great Firewall

Is your website blocked in China? You may be wondering how to unblock it. Unfortunately, there’s no appeal process. The most you can do is remove blacklisted words and content and hope that helps. There’s no official list of blacklisted content, either – Kafkaesque, isn’t it? The Great Firewall blocks by IP address, so multiple websites may be blocked if they share an IP address with a flagged website.

The good news is that the Great Firewall doesn’t block encrypted traffic. There’s no way to inspect encrypted traffic and businesses require encryption for security, so blocking it isn’t an option. This means that any foreign VPN service or proxy server can be used to bypass the great firewall. If you’re in China, you can tunnel out of the Great Firewall of China with a VPN or proxy server and access the full Internet.

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