China: Cracking down circumvention tools

A number of Chinese netizens report that since May 6 2011 visiting overseas website via China Telecom and China Unicom has become highly unstable. This time the disruption mainly affected corporate connections, including university, while ADSL connection at home performs normally.

Some technology bloggers point out that the Great Fire Wall is now able to monitor data flow of local IP and impose restriction when it detect large amount of access to certain overseas IP addresses. Some are worried that the mechanism may result in a de facto white listing of overseas websites.

Corporate and university connection affected

Prominent Technology blogger William Long points out that the blocking this time is targeted at corporate user in order to stop people from visiting overseas website via corporate network and connection.

He runs a test in his office at Shenzhen and found out that he cannot connect to certain overseas IP addresses ( Below shows the detail of the test results:

The Southern Medical University also has suffered from the disruption and explained the situation that China Telecom has restricted the IP access of the university to overseas websites. Zhejiang University also has similar problem [zh], the school VPN's overseas connection has been disrupted. (via William Long)

Data flow monitored

In Sina Microblog, many re-post the following information:

国内各大互联网公司纷纷出现网络问题,目前已知的包括百度、腾讯、阿里巴巴和若干子公司,对于国外网站的访问受限,其中包括苹果的app store也无法正常连接。有人分析说这次断网可能是因为墙已经具有了探测和分析大量加密流量,并对IP地址执行封锁,各大互联网公司的出口被封也在其中。

Many Internet companies suffer from connection problem in Mainland, including Baidu, Tencent, Alibaba and their subsidiary companies. Restriction has been imposed for accessing overseas websites including Apple Company's app store. Some analysts said that the GFW is now able to detect encrypted data flow and block a specific IP addresses. Many Internet Companies’ ports are under restriction.

VPN and circumvention tools forbiddened

In order to tackle with the problem, the IT department of certain corporate has issued the following notices: (via Twitter user @yegle)



Please only visit work related overseas website, don't use circumvention tools to get over the wall.



Upon a close look at the IT email, it said: when visiting overseas website, one has to submit the domain name and explain the purpose of the visit.


原文转载:各位同学, 请大家在使用公司内部网络时,不要使用翻墙工具和VPN等方式访问境外网络信息。 此行为可能导致公司网络出口被封(如:google,msn等正常境外网络访问不稳定),并会为公司和个人带来不必要的麻烦。 请大家在日常工作中一定注意避免。

Re-posting the notice: Dear colleague, when using the corporate network, do use circumvention tools and VPN to get access to overseas websites. Such act would result in the blocking of corporate port to overseas IPs (For example, access to Google and MSN has become highly unstable). It will also bring trouble to the company and individuals. Please be careful and try to avoid this in your daily work.

A notice from the Chinese Academy of Sciences has confirmed netizens’ speculation:

中科院IHEP: 这两天我所网络连续发生短暂无法访问国外资源的现象,经检查确认我所部分用户使用翻墙技术访问非法资源导致网安部门将我所IP地址临时列入黑名单。在此再次提醒大家严格遵守网络使用规范,不要使用非法手段访问敏感/非法网络资源!

CAS IHEP: Our faculty's access to overseas websites have been disrupted in the past few days. Upon investigation, the reason is because some users have used circumvention tools to get access to illegal content, hence the public security bureau has black-listed our faculty's IP. Here I remind everyone to follow the rule when using Internet, don't use illegal means to get access to illegal information!


Join the conversation

Authors, please log in »


  • All comments are reviewed by a moderator. Do not submit your comment more than once or it may be identified as spam.
  • Please treat others with respect. Comments containing hate speech, obscenity, and personal attacks will not be approved.