Twitter and Facebook are some of the more well-known blocked sites in China. In the course of normal usage, it is simple to avoid such sites. (Chinese users, of course, have a variety of alternatives for Facebook, with Sina Weibo in place of Twitter.)

What is more noticeable, when browsing normal websites and blogs, is the severe slowdown caused by the inability to load Twitter’s “Tweet this” and Facebook’s “Like this” buttons that are now commonly embedded on blogs and news sites. Firefox is unwilling to render the page until these load or, presumably, time out, which cripples many sites.

(It’s worth mentioning that all connections to which I had access were relatively slow and unreliable by UK standards, adding to this effect.)

Tor is a standard presence on my netbook, despite not being used for everyday browsing. As expected, the comforting green onion on my taskbar faded to a sickly yellow for my entire journey. I didn’t, sadly, have time to experiment with Tor bridges.

One of the amusing censorship stories of this year has been the discovery that Twitter, and apparently all other sites, is not blocked when using the Kindle’s built-in browser. This is caused by the Kindle automatically routing all browsing requests through Amazon servers located outside of China. I had predicted that this would not be blocked in China; the number of Kindle users are too low, and the browser is just not practical for day-to-day use. Combined with the effort required to force Amazon to reroute requests, it never seemed likely that China would clamp down on the Kindle.

As expected, browsing via the Kindle showed no evidence of blocking whatsoever.

As part of earlier research I have some very basic code to perform DNS lookups for blocked websites, retrieved from the Herdict Project, against remote nameservers. This was run remotely against a list of Chinese DNS servers to compare relative results in different parts of China.

Being physically located in China added little to the data that I already have, except to add a number of DNS servers that weren’t in my initial list. A deeper analysis of this data, along with the data capture from my earlier experiments, is forthcoming. The few extra data points from this trip confirm only that DNS manipulation is widespread for blocked sites, alongside any other more sophisticated means to filter content.

(I will be writing up my FOCI’11 paper here in the very near future, which will go into this work in much more detail.)

On untrusted networks I use VPN software by default where at all possible, for simple security reasons. In almost every location in China, connection to the Oxford University (Cisco) VPN was possible. Where I could not connect, a poor connection is as likely as anything more sinister.

More noticeable was that to achieve anything close to my normal browsing experience, given the sites that I normally visit and the content that they include, I found truly significant differences when using the VPN.

As mentioned above this was not simply a matter of being able to access Twitter and Facebook, both of which I rarely visit directly; nor was it a matter of my connection being dropped because I happened to type a politically sensitive term into a search engine. Instead, the most interesting aspect of directly experiencing this form of censorship was a subtle and generalised degradation of the internet — unpredictable connections, failed links, and slow loading times. All of these are a result of the interconnectivity of the web, and the assumption that cross-site links are equally available. (Wikipedia being blocked, however, was surprisingly restrictive. One interesting highlight of restrictions on connectivity is to draw attention to your own browsing habits.)

In summary, my brief experience of Chinese internet censorship was strikingly different to my expectation. The majority of reports, in my experience, focus on the dramatic blocks of major websites, or on heavy-handed filtering of search results. In practice I was far more struck by the continual, low-level pressure that censorship imposes on normal usage, even though, as a lǎowài, I was largely unaffected by wider social or legal concerns from trying to access blocked sites. Most notably, I was surprised by the level of collateral damage that broad-scale filtering imposes on a wide range of largely unrelated sites.

While the internet in China is by no means unusable, the restrictions are tangible. The context of my own usage, mainly restricted to English-language websites based in the west, is unlikely to be representative of the experience of a Chinese user. My inability to meaningfully browse and engage in Chinese-language websites prevented me from experiencing the less technical aspects of filtering: self-censorship, pro- and anti-government rhetoric, selective news reporting and others.

I can say that I was very glad to be back with a nice Clean Feed in the UK.