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Sat, Feb 04, 2012

Is the Great Firewall blocking outgoing traffic only?

Connection reset. That is the famous response shown to web users in China when they are trying to access one of the over 2600 websites and searches that have been blocked by the authorities. But what is actually blocked and what is causing the connection disruption? Our research suggests that the Great Firewall (GFW) does not filter any incoming data, but only the outgoing traffic.

It is often said that the GFW imposes three types of censorship. The first one is DNS poisoning. For example, this happens when users in China attempt to access facebook.com. The name servers return an incorrect IP address which doesn't work. The browser tries to load the website for a certain period of time until the whole exercise 'times out'.

The second type of censorship is keyword-based. For example, if one tries to search on Google for facebook, freedom  or some of the other 250+ blocked searches, the connection is immediately reset. In addition, users are restricted from accessing any content on the same website for a minute or so.

The third type is supposed to be content based. Regardless of what was searched for or the address that was entered, if the content contains certain keywords, it is supposed to be blocked. This is where our findings become relevant. They suggest that the GFW doesn't interfere at all with the content that is sent back to the web user in China.

Tue, Jan 03, 2012

Gmail is getting faster but still not as fast as dial-up

Many in China have complained that Gmail is so slow that it is almost impossible to use (see our original story from March 2011 - Gmail now 45 times slower than QQ). We have continued to gather data on the Gmail situaiton in light of Google's continued operation in China. With more data we can now show how the situation has developed since March. The results are clear in this chart:

All foreign webmail providers are considerably slower than domestic competitors (QQ is included for comparison). Out of Gmail, Hotmail and Yahoo, a distressed Yahoo, whose local partner in China is Alibaba, is consistently the fastest free foreign email provider. Hotmail has at times challenged Gmail to a race to the bottom. Using the same comparison as in March, Gmail is now only 9 times slower than QQ and has seen a considerable improvement in speed since September.

One way to put the speed of Gmail into perspective is to compare today's access speed with old dial-up modems, for those that remember. In the 1990s, they provided speeds up to 56 kbps, or roughly 7000 bytes per second. That is considerably faster than the average speed of either Gmail or Hotmail, when accessed from within China in 2011.

Apart from speed, the main problem with Gmail in China is instability. Rather than blocking the service outright, it seems that the authorities have chosen to impose occasional, random outages. Looking back over the year (from March onwards), we can see the following:

Surfing the Internet in China slower on Sundays

Browsing websites is often a slow and frustrating experience in China. Apart from blocking over 2600 websites and searches, the Great Firewall also imposes a serious bottleneck on speed. There have been rumors that the Internet is especially slow on Sundays. Analyzing more than 80,000 tests executed by our system from March to November this year, our data seems to confirm this suspicion.

The tests consist of downloading the front page of each of the world's 500 most popular websites, as defined by Alexa. Apart from aberrations in March and June, download speeds on Sundays have consistently been between 8 and 25% slower than the average of the other days of the week. Here's the full test data summary (all speeds in bytes/second):

Fri, Dec 16, 2011

Wukan blocked only on Weibo

BBC reported yesterday that Wukan, a village in south China where a major land-grab protest is taking place, has been added to the list of blocked keywords on Weibo (China protest in Guangdong's Wukan 'vanishes from web'). Our system does not yet monitor Weibo keywords(We do monitor them now ), but we have done a manual search and come up with this list:

KeywordStatus
乌坎Blocked
WukanBlocked
WKNot blocked
禄丰Not blocked
LufengNot blocked

The message shown when trying to search for a blocked keyword on Weibo is:

根据相关法律法规和政策,“wukan”搜索结果未予显示

This translates into: According to relevant law, regulations and policies, search results for Wukan cannot be displayed.

However, Weibo aside, Wukan and other related search terms are not blocked on Google Search, nor on Wikipedia (neither the English or Chinese version), nor on Western news sites. These are all listed top right on this page together with their latest status, continously updated by our system.

The fact that such a sensitive issue is blocked on Weibo only might testity to the importance that the authorities attribute to the Chinese microblogging service compared to other media.

 

Fri, Oct 14, 2011

All WordPress blogs blocked in China

WordPress.com, the famous blog tool, was blocked in China this week.

A quick look at different blogs hosted by WordPress (searching for wordpress in our new search above) shows the following:

Number of blogs blocked before this week: 7 our of 21 (33%).

Number of blogs blocked now: 21 out of 21 (100%).

The main wordpress.com website is also blocked. Interestingly, wordpress.org is still not blocked. So Chinese users can still access that website to download the WordPress software, but they have to host it somewhere else.

Mon, Oct 10, 2011

We've moved to greatfire.org

Today we've moved to a new domain: https://greatfire.org. Here are some notes on what this means:

We're not blocked in China

Though it may only be a question of time until this changes, for now our website is accessible in China without a VPN or proxy. Back in March, before we were blocked, we started getting traffic from Weibo (the biggest Chinese equivalent to Twitter) and we hope to be able to inform Chinese users on the extent of online censorship here.

We're on a secure server

Notice that our address starts with HTTPS. This means that all traffic between your browser and our server is encrypted. And the result of this encryption is that it is impossible for the Great Firewall to intercept the traffic, if you're viewing our website from China. HTTPS is a term to remember, it's the biggest reason why the authorities have semi-blocked access to GMail here.

.org as in non-profit

We are a non-profit organization which is now reflected in our name. Our mission is to bring transparency to online censorship in China. We do need your help to make our operations sustainable.

Feedback is very welcome, as always.

Tue, Aug 23, 2011

How our tests are done

We have been detecting which websites are blocked in China since February this year. Using our tool and contributions from our visitors, we've created the most complete database anywhere of what's blocked by the so-called Great Firewall of China, including 2200+ blocked websites and 200+ blocked searches. But how accurate is our data?

When a website is tested, it's always done by comparing the results of trying to access it from A) a computer outside China and B) a computer inside China. This way, a website that is simply not working is not labelled as blocked. A website that works when accessed outside of China but fails when tested from inside China, on the other hand, will be labelled as blocked.

This makes our data more accurate, but not perfect. Another difficulty is that the Great Firewall often changes temporarily. A given website that was previously accessible may be blocked for, say, 20 minutes. The opposite is also true. Blocked websites are sometimes temporarily accessible. Examples include Facebook (March 28, April 25) and YouTube (July 31, Aug 15 etc).

To tackle this particular challenge, our scripts always re-run testing of a website once more, after it's status has changed. In most cases, temporary changes are quickly detected and the websites are labelled correctly again. In some cases, however, if the change lasts somewhat longer, it may take up to a week for our system to re-label the website correctly. So, for example, Paypal was tested to be blocked twice on Aug 22. It's now accessible again. But it will take several days before our system automatically tests it again. Meanwhile, it's labelled as blocked.

Thu, May 19, 2011

Who is protecting the VPNs?

In recent days news has spread that China is cracking down on VPN use (Guardian, Global Voices). Chinese internet users, particularly those in universities, are finding it increasingly difficult to make use of VPNs to circumvent online censorship and access blocked websites. This seems to be a continuation of the increased censorship witnessed this year, including temporary blocks of GMail and LinkedIn.

While important, this development leaves an obvious question unanswered: Why do the authorities not block access to the main websites of the major VPN providers? Each serious provider offers access to a number of servers around the world and blocking actual usage of these is somewhat complicated. The main websites, however, could be blocked in an instant. After all, the Great Firewall has no problem constantly blocking other websites such as Youtube and Facebook.

There are three apparent possibilites. The first is incompetence. The authorities might simply not be aware of the VPN providers that are not blocked. This seems unlikely for two reasons. First, all it takes is a Google search of, say, "VPN China". Blocking the top 10 results would go a long way to making VPN access in China more difficult. Second, some providers, such as StrongVPN, are in fact temporarily blocked from time to time.

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