Posts tagged “Internet Censorship”

Pakistan & YouTube

UPDATE — In attempting to block access to YouTube, Pakistan ended up making YouTube inaccessible to everyone — not just everyone in Pakistan, but everyone! Martin A. Brown provides some of the technical details and a time line here (Thanks Steven!):

Just before 18:48 UTC, Pakistan Telecom, in response to government order (thanks nsp-sec-d) to block access to YouTube (see news item) started advertising a route for to its provider, PCCW (AS 3491). For those unfamiliar with BGP, this is a more specific route than the ones used by YouTube (, and therefore most routers would choose to send traffic to Pakistan Telecom for this slice of YouTube’s network.

I’ve updated with a screen capture from an ISP in Pakistan from the Don’t Block the Blog Campaign. As noted, since most ISPs route through the Pakistan Internet Exchange which only blocks IP addresses, many users in Pakistan won’t have access to YouTube at all. Users of the ISP TWA appear to have partial access.

The Global Voices Advocacy blog has good coverage of the story and has also posted a copy of the blocking order. (Older blocking orders from Pakistan available here, here and here.) But what I found interesting is that the blocking notice contains a full url to a video and the url in the blockpage is which suggests that while the front matter at may be accessible all the videos are not since they are accessed via /watch?. But perhaps the blockpage is incorrectly printing a partial url, but still, its something worth checking. The proxy is only blocking the targeted video.

Democracy “Magnified”

The “magnify” component of the Search Monitor project attempts to match the top ten results from Google/Yahoo with the top ten results form the China-specific versions of Google/Yahoo in order to note the similarities and differences in terms of censored, returned (the website is in the top ten of the both the .com and .cn versions of the search engine) and indexed (the website is in the top ten of the .com version, but not in the top ten of the .cn version, but is not censored). It also compares the results based on whether or not each website is hosted in China or ends in a .cn. This is taken as a measurement of “authorized” content that is unlikely to present information that China would block.

But, is this a worthwhile measurement?

Nine out of the top ten results for a search for 民主 in and are the same. The only difference is that which appears as number two in is censored in and, as a result, rounds out the top ten in

But despite only having one censored site 7 of the top ten results for 民主 are either hosted in China or end in a .cn domain suffix. This number increases to 80% in

There is no overlap between and, drastically different results are returned. Of the top ten results in 4 are censored in

All 10 of the results from are hosted outside of China and all 10 of the results from are hosted inside China.

However, how does the content of the actual results match up? On this I require some help. Qualitatively, what content are users in China missing out on? How relevant are the censored sites?

Results for 民主 from

Results for 民主 from

Censored in

Results for 民主 from

Results for 民主 from

Censored in

Does the hosted in China or ending in .cn measure make sense when the content itself is analyzed?


Wikileaks, the transparency web site that allows anyone to upload leaked materials, was shut down after a California Judge ordered its domain registrar to:

immediately clear and remove all DNS hosting records for the domain name and prevent the domain name from resolving to the website or any other website or server other than a blank park page, until further order of this Court.

The site is still available here:

The Citizen Media Law Project has the case documents and analysis and the story has now been picked up by the mass media. But what’s caught my attention is who is not talking about it. Glad to see the usual suspects raising the issue.

News Cluster: China

There has been a flurry of articles on Internet censorship in China recently. One very interesting AFP article suggests that China may relax its restrictions and allow access to some sites currently blocked by the GFW:

Plans to tear down the so-called Great Firewall of China were being debated and a decision was expected soon, said Wang Hui, head of media relations for the organising committee…

“I believe you will be able to (access banned sites such as the BBC) but I can’t give you a promise yet. The relevant government departments are still working on it,” she said.

That’s something to keep an eye on for sure.

An article in The Guardian discusses the rapid growth of Internet usage in China the related effects. The article discusses how the Internet, and blogs in particular, have created “competing public opinions.” This is an interesting way to frame the topic as censorship in China is often characterized as monolithic when in fact there is a significant amount of competition in the realm of ideas. Even within a confined informational space there is considerable movement — what I’ve called wiggle room in the past — if one looks for it.

However, the article repeats the charge that China is exporting their Internet censorship technology:

Campaigners suspect China is passing its censorship know-how to Cuba, Vietnam and several African countries.

Now, I don’t doubt that others are looking at the forms of control China is applying to the Internet and evaluating how they too can keep the benefits, particularly economic, that come with the Internet while minimizing its use for free expression but I’m not so sure that this means that China is actively exporting censorship technology. As it currently stands, ONI found no filtering in Zimbabwe despite reports to the contrary. While Vietnam does censor the Internet it does so in a very different way than China does. Cuba may conduct a limited amount of filtering, but it is also much different than that in China. RSF reported:

There is hardly any censorship of the Internet in Internet cafes. Tests carried out by Reporters Without Borders showed that most Cuban opposition websites and the sites of international human rights organisations can be accessed using the “international” network. In China, filtering for key-words makes it impossible to access webpages containing “subversive” words. But, by testing a series of banned terms in Internet cafes, Reporters Without Borders was able to established that no such filtering system has been installed in Cuba.

While not ruling out the possibility, I am skeptical of this claim based on my experience with testing filtering systems in these countries. (What’s more interesting is that Comcast’s filtering in the USA is more like the GFW than any of these countries.)

The New York Times published an article that looks at the resistance to Internet censorship in China. It picks up on the theme of backlash that I’ve suggested comes about when over blocking occurs. When common web sites and services are blocked, it helps turn normally apolitical people into activists. The NYT reports:

For a vast majority of Internet users, censorship still does not appear to be much of a factor. The most popular Web applications here are games and messaging services, and the most visited Internet sites focus on everyday subjects like entertainment news and sports. Many, in fact, seem only vaguely aware that China’s Internet universe is carefully pruned, and even among those who know, a majority hardly seems to care.

But growing numbers of others are becoming increasingly resentful of restrictions on a wide range of Web sites, including Flickr, YouTube, Wikipedia, MySpace (sometimes), Blogspot and many other sites that the public sees as sources of harmless diversion or information. The mounting resentment has inspired a wave of increasingly determined social resistance of a kind that is uncommon in China.

The Financial Times reports that Guo Quan, a Chinese scholar, is planning to sue Google because a search for his name in is censored. If some one gives me the proper Chinese translation for his name I can check this out further. (In English it returns results, using 郭泉 results are also returned along with Google’s standard censorship notification. The name itself is a censored term as a search for it with a non-existent domain will produce the censorship notification as well. and Baidu produce no results. They will produce results if something is appended to the search (, baidu)

The Atlantic published an article on censorship in China (it seems to be gone now, here are links to Google’s cache: 1, 2, 3, 4) that takes on the challenge of explaining the technical measures used to censor the Internet. The article also discusses circumvention and the self-censorship component that is so integral. The article concludes with some salient points regarding the important role of domestic censorship as well as the widening space for dialog:

It would be wrong to portray China as a tightly buttoned mind-control state. It is too wide-open in too many ways for that. “Most people in China feel freer than any Chinese people have been in the country’s history, ever,” a Chinese software engineer who earned a doctorate in the United States told me. “There has never been a space for any kind of discussion before, and the government is clever about continuing to expand space for anything that doesn’t threaten its survival.” But it would also be wrong to ignore the cumulative effect of topics people are not allowed to discuss.

However, the are several issues with the technical analysis as well as underlying tones of “exceptionlism” that obscure some of the bigger picture issues.There seems to be confusion over surveillance and filtering. Its best to think of filtering a set of rules, if packets contain something that violates the rules certain actions are taken. If a destination IP address is on a block list, the connection is not made, if packets contain certain keywords reset packets are sent to the source and destination to terminate the connection. Surveillance implies that someone is watching the traffic, or more logically it is stored, parsed and then someone looks at it. When surveillance and filtering are (con)fused together you get something strange like this:

Thus Chinese authorities can easily do something that would be harder in most developed countries: physically monitor all traffic into or out of the country. They do so by installing at each of these few “international gateways” a device called a “tapper” or “network sniffer,” which can mirror every packet of data going in or out. This involves mirroring in both a figurative and a literal sense. “Mirroring” is the term for normal copying or backup operations, and in this case real though extremely small mirrors are employed. Information travels along fiber-optic cables as little pulses of light, and as these travel through the Chinese gateway routers, numerous tiny mirrors bounce reflections of them to a separate set of “Golden Shield” computers.Here the term’s creepiness is appropriate. As the other routers and servers (short for file servers, which are essentially very large-capacity computers) that make up the Internet do their best to get the packet where it’s supposed to go, China’s own surveillance computers are looking over the same information to see whether it should be stopped.

If one conducts passive surveillance with a tap, one cannot then go back and interfere with the packets. For filtering, such a setup is not needed. You just route the traffic though something that filters — basically all routers can filter. The filter looks at the packets and matches them to the rules. There are no “tiny mirror” or whatever. If you want to conduct passive surveillance you can use a tap and record the traffic for analysis. The two things are not really related. Moreover, internet surveillance is not something that only China does or that is easier for China to do — a quick look at the most sophisticated internet surveillance system in world can demonstrate that.

On to the mechanisms:

DNS tampering
is explained well (although there may be some new variant). An important point is that most ISPs have their own DNS servers, managing a centralized system could be awkward (though not impossible), and users can use other uncensored DNS servers.

IP Blocking: This technique is incorrectly explained in the article.

While your signal is going out, and as the other system is sending a reply, the surveillance computers within China are looking over your request, which has been mirrored to them. They quickly check a list of forbidden IP sites. If you’re trying to reach one on that blacklist, the Chinese international-gateway servers will interrupt the transmission by sending an Internet “Reset” command both to your computer and to the one you’re trying to reach.

If packets are sent (trying to establich a tcp connection) for a particular IP and they pass through a router configured to block packets for that IP, the router will block those packets. Thats it. There is no connection ever made. If you sniff such a connection you will only see outgoing syn packets and nothing else. No reset packets are sent. There’s no “mirror” processing anything while you wait.

URL keyword block – This technique is actually the resest one described under IP blocking. If any part of the get request contains certain keywords — and domain names are often used as keywords — a reset packets will be sent to both the source and destination to terminate the connection. When is it triggered? This is confusing because the GFW’s keyword filtering is bi-directional but in my experience it is triggered on the way out of China. I say this because you can trigger it by requesting non-existent content. Depending on how long it takes to send the reset packet you may receive some of the content you requested which is what makes it appear that the filtering happens on the way in. After receiving reset packets the source and destination will not be able to connect to each other for a period of time.

Body Filtering – This is a bit of a tough one. Basically, if you create a web page with a keyword that normally triggers the reset packets if it appears in the url path, you can access it fine from China. I originally thought that this meant that body content was not filtered, but if you create a large page of such words the reset packets can be triggered. This may mean that a sampling of packet are checked, not all packets. In any case the behavior is the same as discussed above — the source and destination cannot connect to one another for a period of time. If you keep requesting the content you trigger more reset packets so t takes longer to be able to connect, but if you wait, and then trigger the reset packets again it won’t be longer the second or third time. There’s no escalating punishment.

Bi-directional keyword filtering

As Chinese-speaking people outside the country, perhaps academics or exiled dissidents, look for data on Chinese sites—say, public-health figures or news about a local protest—the GFW computers can monitor what they’re asking for and censor what they find.

Again, the keyword filtering is bi-directional, if you trigger it on connections to China the same behavior applies. Again, the issue of “monitoring” in this context implies that there’s something intelligent and deliberate about the filtering. If the packet matches the rules, it triggers the filtering mechanism, in this case reset packets.


Easy is a relative concept here. If a user chooses to break the law and acquires the necessary knowledge to by pass censorship then, yeah, it can be easy. You can buy vpn access — at least until lots of people start using and then it gets blocked – or use an encrypted proxy — at least until it gets blocked. They don’t need to block all VPNs, they can just block the IP addresses of those they want — those that become popular amongst citizens seeking to circumvent the GFW.

But despite the issues with the technical mechanisms the article is dead on with its conclusions:

What the government cares about is making the quest for information just enough of a nuisance that people generally won’t bother. Most Chinese people, like most Americans, are interested mainly in their own country. All around them is more information about China and things Chinese than they could possibly take in… When this much is available inside the Great Firewall, why go to the expense and bother, or incur the possible risk, of trying to look outside?

All the technology employed by the Golden Shield, all the marvelous mirrors that help build the Great Firewall—these and other modern achievements matter mainly for an old-fashioned and pre-technological reason. By making the search for external information a nuisance, they drive Chinese people back to an environment in which familiar tools of social control come into play.

Ding! We have a winner.

A Search for Human Rights

The Search Monitor Project: China focuses on assessing the level of transparency with regard to the self-censorship practices of search engine companies as well as the mechanisms and effects of this political censorship. (For background information, see this and this.) The following is a step by step process of a search for “human rights” (人权).

The first step is to retrieve a result set from the (uncensored) Chinese version of Google. Each result is parsed to its domain name ( becomes “”).

The second step is to use the “site:” modifier to restrict results to the domain. The censored versions of Google and Microsoft can be queried directly, but Yahoo and Baidu must be queried from inside China because they are hosted inside China. This is because the bi-directional filtering of China’s “Great Firewall” (GFW) will block the inbound connections due to the presence of “” in the search query. Conversely, search from inside China to Google or to Microsoft will be blocked because of the GFW — but since we are interested in search engine censorship it is necessary for us to remove the effects of the GFW.

The censored results for the top ten results from Google for the query 人权 are:

Keyword Translation Google MSN Yahoo Baidu
人权 human rights 1 / 10 3 / 10 1 / 10 1 / 10

The common site, censored by all four search engines, is This is the website of Human Rights Watch. Google, acting the most transparently, provides a notification that results have been removed and since the search has been restricted, using “site:” we can conclude that is censored specifically and deliberately. Yahoo provides a notification, but since it appears at the bottom of every page regardless of whether the results are censored or not we are left to assume that it was never indexed because Yahoo China operates it web crawlers from behind the GFW. Baidu also operates its crawlers from behind the GFW so, like Yahoo, sites blocked by the GFW are not indexed. Microsoft uses the same de-listing mechanism as Google but has removed the censorship notification they formerly displayed. We therefore assume that it has been censored because there are no results when using the “site:” modifier (results do appear in the English version) but the lack of transparency reduces the accuracy of the claim.

The two other sites from (uncensored) Google’s top ten results for 人权 (human rights) are: and

URL Google MSN Yahoo Baidu

Meta: org | | 701 | US | UUNET – MCI Communications Services, Inc. d/b/a Verizon Business

Censored Censored Censored Censored

Meta: org | | 14907 | US | WIKIMEDIA Wikimedia US network

Indexed Censored Indexed Indexed

Meta: com | | 4812 | CN | CHINANET-SH-AP China Telecom (Group)

Indexed Censored Indexed Indexed

It is interesting that Microsoft censors wikipedia while Yahoo and Baidu index it because wikipedia is generally blocked by the GFW. A possible explanation is that due to the fact that the GFW is not 100% consistent or accurate with its keyword filtering the crawlers were able to index normally blocked sites.

I am not familiar with but it is hosted inside China and is thus an unlikely candidate to host information that the government would want to censor. The fact that it is index by all the other three search engines supports this. While this could be a case of “collateral damage” due to Microsoft’s lack of transparency (the possibility that it is not censored, it is just not indexed) it is indexed in the English version of Microsoft’s search engine.

The “magnify” component of this project attempts to match the top ten results from Google/Yahoo with the top ten results form the China-specific versions of Google/Yahoo in order to note the similarities and differences in terms of censored, returned (the website is in the top ten of the both the .com and .cn versions of the search engine) and indexed (the website is in the top ten of the .com version, but not in the top ten of the .cn version, but is not censored). It also compares the results based on whether or not each website is hosted in China or ends in a .cn. This is taken as a measurement of “authorized” content that is unlikely to present information that China would block.

As noted above, there is only one censored site, the other nine results are also returned in the top ten of the censored .cn version of Google.

However, even in 4 of the top 10 sites are hosted in China or end in a .cn leaving only 6 sites to represent alternative information. When the censored site is removed, the version moves to 50/50 split between authorized and potentially unauthorized information. While this case doesn’t show a dramatic difference, other search queries, particularly those specific to contextually relevant information often do.

This vs. comparison uses the top 10 results from for a comparison. With this result set 8 sites returned in are censored, the remaining 2 are indexed but not returned in the top 10 in

While all 10 results in are hosted outside of China all 7 results in are hosted in China or end in a .cn. This helps show how significant the censored sites are in comparison.

Although the total number of censored sites may be low, especially when compared to the amount of indexed sites, the significance of these sites in providing alternative information should not be underestimated.

Search Monitor Project: China

Search engines are increasingly censoring their results, often by geographic location, having a significant, negative impact on the right to freedom of expression. The most advanced cases of censoring political content is in search engines that market a version of their product in China. This project aims to expose and monitor the censoring practises of search engines with a specific focus on China.

Building upon efforts to assess the level of transparency (reading this first is probably a good idea) with regard to search engine censorship, this project aims to compare the level of censorship across the China-specific search engines of Google, Yahoo, and Microsoft as well as the domestic Chinese search engine, Baidu. The goal of comparison poses some significant methodological problems as the presence or absence of censorship notification, mechanism of censorship (and irregularities therein) and physical location of the servers themselves all add additional layers of complexity.

In attempting to develop an automated system that can reasonably compare the search engines some additional methods which would be well suited to one search engine but for which comparable data could not be generated from the others have been delegated to separate search engine-specific projects. As a result of the focus on comparability the methods outlined below not only build upon existing research in this area but can hopefully explain some of the anomalies previously identified. After reviewing previous reports by Reporters Without Borders and Human Rights Watch I sketch out methods that attempt to provide an accurate, automated comparison between the search engines.

Previous Research

In June 2006, Reporters Without Borders (RSF) conducted a comparison of the four search engines Google, Yahoo, Microsoft, and Baidu (later updated to also include Sohu and Sina) by entering key words into the search engines and analyzing 1) the presence or absence of any results and 2) the content of the results by classifying each returned web site (URL) as either “authorized” or “unauthorized” which presumably refers to whether or not the source is controlled by or supports the government of China or whether it contains critical, alternative information. While this report is an innovative attempt and comparison is suffers from methodological issues that affect the accuracy of the results.

First, the report is actually about the ranking of results rather than censorship. The top ten results were analyzed based on their content, not on whether a web site had been censored (de-listed/removed) from the results set. While the removal of censored sites will likely affect the combination of “authorized” vs. “unauthorized” sources it does not tell us what sites are censored or if the “unauthorized” sites are not censored but just do not appear in the top ten results. Since localized search engines often algorithmically privilege sites in the local language, ending in the country’s domain suffix (e.g. .cn) and possibly even being hosted within the country it affects where foreign hosted “unauthorized” content appears in the result set. Thus an “unauthorized” site may not appear in the top ten results of the localized search engine even though it does in the uncensored version. Instead, the site may appear further down in the rankings.

Second, the testing of the search engines did not account for China’s national filtering system, often labeled the Great Firewall of China (GFW). Consequently, the results concerning “no results” and “no results + user banned” should actually be seen in reverse. Since Yahoo and Baidu are physically located in China the search queries made by RSF were filtered by the GFW on their way to the Yahoo and Baidu servers. If the same search were conducted from China, the search queries would not pass through the GFW and would not be filtered. The search queries RSF made to Google and Microsoft did not pass through the GFW because those servers are not located in China and therefore results were always returned. However, had those same search queries been made from China to Google and Microsoft they would have been filtered by the GFW and would have been designated “no results” and “no results + user banned”. The failure to account for the GFW prevented RSF from accurately interrogating the filtering of the search engines because a distinction was not made between filtering by the search engines and filtering by the GFW. If the tests had been conducted from inside, rather than outside, of China the report would have captured the behaviour experienced by users in China who are censored by both the GFW and the search engines and perhaps are agnostic about which one is doing the censoring since the result is the same: censorship.

In August 2006, Human Rights Watch (HRW) released an impressive and detailed comparison of Google, Yahoo, Microsoft, and Baidu. Two approached were used in this report: the first focused on identifying censored sites the second on whether or not the result set returned from a search for a specific key word query was censored. The first approach involved using a list of 25 websites and searching for each website in each search engine (using the site: modifier, discussed below, when possible). If a “censorship notification” appeared and there were no results the web site was censored, but the report also noted instances in which the message appeared but some partial results appeared as well. In other cases, there were no results and since there was also no censorship notification (or a censorship notification that always appears and has no relationship with the results) it was suspected that the web site was censored. In this way, HRW was able to determine how many of the 25 sites were censored in each search engine.

HRW tested from both inside and outside of China and was thus able to isolate search engine filtering from that conducted by the GFW of China. HRW notes that queries to Yahoo from outside China generated errors (as we saw in the RSF study) and we now know that this is due to the bi-directional filtering of the GFW (see below). The partially censored results (what I call “Page Censored” below) can result from at least two reasons. The first, is that some search queries automatically trigger the censorship notification regardless of whether the results have been censored or not and second because the filtering algorithms of the search engines are imperfect. Google, for example, does not handle port numbers properly and fails to remove such pages and Microsoft does not handle domains by their root ( and therefore sub-domains ( or may not all be removed. Microsoft also does not properly handle URLs that begin with “https”. In such cases partial results may be available despite the search engines attempts to censor.

Another issue (which is still an issue in the methodology discussed below) concerns search engines not censoring pages directly. Both Yahoo and Baidu operate the crawlers that index websites from inside China and thus do not index sites that are blocked by the GFW. This removes the need for the search engines to censor their results, as the index itself is already censored by the GFW. This means that there is not a credible technical way to distinguish between sites that are not indexed and sites that are censored. Another issue is that the GFW is not perfect, and normally censored sites sometimes end up in Yahoo & Baidu’s index. There have also been some cases in which Yahoo has removed indexed sites — those not blocked by the GFW — and used a censorship notification as Google does and Microsoft did previously. Therefore, for the most part, Yahoo and Baidu do not need to censor their results, because their index is already censored because their crawlers operate form within China and cannot visit blocked sites to begin with.

The second approach used by HRW focused on the issue of keyword filtering by search engines. The question is simple enough, if I search for keyword “a” will I get censored results “b“? However, the lack of transparency on the part of the search engines makes the answer to this simple question difficult. HRW used a list of 25 keywords to query the search engines and inferred possible censorship by comparing the results from censored China-specific versions of Google, Yahoo and Microsoft and their US counter-parts as well as noting the appearance of a censorship message. (Baidu had no such counterpart at the time, but perhaps Baidu Japan can now be used for this purpose.)

Comparing result sets can be problematic because of the algorithmically determined rank of the results. What appears on page one in the top ten results in may appear on page twenty-five in In the case of Yahoo and Baidu GFW-censored sites are not indexed at all and so will never appear no mater what one searches for. Another method is to use the difference in the estimated page count as an indicator of censored results. But the estimated page counts can vary considerably between servers and language/region-specific versions. Microsoft, for example, returns very few Chinese language results in their default English language search engine making comparison virtually impossible. As noted by HRW, even the presence of the censorship notification may not be reliable. In some cases the censorship notification will appear based on the keywords in the query not on the results returned. (You can restrict the results to a non-existent site and still get the censorship message.) In other cases, it has nothing to do with what was used as a query for example, a non-politically sensitive term) but the censorship message appears because a URL has been removed/de-listed. In other cases, some keyword queries return results and a censor message not because results have been removed but because results are only returned from a set of “white listed” sites. Compounding the problem, the censorship message appears to be page specific (at least in the case of Google). That is, if one searches for keyword “x” and gets back ten results there may be no censorship message, but when one click on “Page 2” and gets results 11-20 which do contain a censored site the censorship notification will appear. (Therefore, if you set the preferences to retrieve 100 results will one may be more likely to encounter the censorship notification than if restricted to 10 results?).

HRW accounted for such variance through manually checking results in addition to the estimated page count comparisons and the presence of a censorship notification. Not only does this involve extensive manual labour but also an expertise in analyzing the content for political significance. For example, HRW manually assessed and compared the first three pages of search results for Yahoo and Yahoo China. HRW’s efforts in the regard stand out as an example of the quality needed for this line of research.


The Search Monitor Project currently contains two related but separate components. The first, Generalized Comparison : Keywords and Urls, focuses on a generalized comparison between the China-specific versions of Google, Yahoo, Microsoft and Baidu. The second, Magnify: A Google-Google, Yahoo-Yahoo comparison, focuses on comparisons between the Chinese-language “global” versions of Google and Yahoo and their special censored China-specific versions.

While the core testing methods are the same, the Magnify: A Google-Google, Yahoo-Yahoo comparison contains some additional elements that allow for a more fine grained analysis. These will be noted below when appropriate.

Generating a URL Set

A set of sixty keywords have been selected covering the broad topical categories of censorship circumvention, falun gong/dafa, political sensitivities and social taboos. Search queries in “uncensored” engines (the Chinese language versions of Google or Yahoo) are used to generate lists of sites that are checked in censored search engines.

A query term, such as “人权” (human rights), is used to retrieve results from an “uncensored” search engine, such as

The websites from the “uncensored” results are parsed to retrieve the domain (including sub-domains).

A list of URL results, usually ten, are retrieved. A URL such as is shortened to

Each domain name is checked in each censored search engine.

Determining a Censored site

These domains are checked in the censored search engines using the “site:” modifier. The “site:” modifier restricts the results set to pages of a specific host name.

“” (without the quotes) is used as a search term in in censored search engines to restrict the results to only those from the web site

In cases where the censored search engine being tested display as special message indicating that results have been censored, a “censor message”, that relates to the specific search query domains that produce no results when queried with the “site:” modifier and contain a censor message are labeled as “Censored” while domains that return some results but contain a “censor message” are labeled as “Page Censored”.

In the cases where there is no censor message, or the censorship message appears on every page and bears no connection to the results, domains that produce no results when queried with the “site:” modifier are labelled as “Censored.”

Depending on the current behaviour of search engines there may be ad hoc additions. – censored = censor message + 0 results, pagecensored = censor message + some results – censored = 0 results, pagecensored = results that only contain urls beginning with “https” (no longer a censor message, failure to exclude “https” urls was noted when the censor message was in place and is thus used as “Page Censored”) – censored = 0 results, censor message is ignored because it appears on every page, it bears no relation to search results – censored = 0 results

It is important to note that sites that are simply not indexed by the search engine will appear as “Censored” thus possibly inflating the total amount to censorship attributed to search engines that do not have a censor message that is related to the results. This can be slightly compensated for by looking at the overlap of censored sites among search engines. In addition, since this is a normative project advocating transparency, should serve as an incentive for search engines to implement a censor message that is related to the results.

The Magnify: A Google-Google, Yahoo-Yahoo comparison project contains the classifications “Returned” and “Indexed” in addition to “Censored” and “PageCensored”. “Returned” refers to URLs from the the result set from the “uncensored” search engine that are returned in the result set from the censored search engine. “Indexed” refers to URLs from the the result set from the “uncensored” search engine that are not returned in the result set from the censored search engine, but are not censored. Using this method, the top ten results or a query in Google (Chinese) can be compared with the top ten results of Google China and can be categorized by “Returned”, sites that are common to both results sets, “Indexed”, sites in the top ten uncensored but not in the top ten of the censored results, and “(Page)Censored”, results that are actually censored. In addition, each URL in both result sets is check to see of it it hosted in China or ends in a .cn domain suffix.

The Great Firewall (GFW)

Borrowing a phrase from my colleagues Richard Clayton, Steven Murdoch and Robert Watson, it is necessary to ignore the filtering conducted by China to accurately test levels of censorship by the search engines themselves. As Clayton and Murdoch reveal, Internet traffic to and from China passes through a filtering system that is bi-directional – it affects both inbound and outbound traffic – (China also blocks outbound connections to IP addresses, but this does not interfere with the ability to test the search engines) which disrupts connections if the presence of particular keywords are detected. Often, China will designate a domain name as “key word” this disrupting access for any request that contains that domain name. This is important as queries directed to search engines hosted in China use the “site:” modifier followed by a domain name.

In order to avoid interference from the China’s filtering system, the China-specific versions of Google and MSN, which are hosted outside of China, are queried from outside of China and the China-specific versions of Yahoo and Baidu, hosted inside China, are queried from inside China.

The censored search engines, and are checked from outside of China.

The censored search engines, and are checked from inside of China.

In addition to affecting how to test each search engine, the location of the search engine to the GFW also affects how the search engines censor. Google and Microsoft, located outside of China, must remove, or de-list, specific sites from the results. Yahoo! and Baidu both operate their search spiders from inside China. The results in a situation where, because of China’s gateway filtering, the crawlers that index content for these search engines cannot access sites that China blocks. – – [08/Feb/2008:08:05:40 -0500] “GET / HTTP/1.1” 200 12258 “-” “Baiduspider+(+” – – [08/Feb/2008:09:04:42 -0500] “GET / HTTP/1.1” 200 12258 “-” “Baiduspider+(+” – – [08/Feb/2008:11:46:31 -0500] “GET / HTTP/1.1” 200 12258 “-” “Baiduspider+(+” – – [07/Feb/2008:16:58:33 -0500] “GET /robots.txt/ HTTP/1.0” 200 24 “-” “Mozilla/5.0 (compatible; Yahoo! Slurp China;” – – [07/Feb/2008:16:58:35 -0500] “GET / HTTP/1.0” 200 19068 “-” “Mozilla/5.0 (compatible; Yahoo! Slurp China;”

Thus Yahoo! rarely has to de-list specific websites, most are just not indexed in the first place. However, this also leads o situations in which sites blocked by China and de-listed by Google and Microsoft are index by Yahoo!. The GFW is not 100% effective and occasionally crawlers operating from inside China are able to index a normally blocked site which then appears in their search results.

It is also important to note that sites indexed by the search engines that are blocked by the GFW will still be inaccessible to users in China.

Types of Results

Generalized Comparison : Keywords and Urls

This component shows each of the keywords used as search queries in an “uncensored” search engine and the number of the URLs from that result set that are censored in the China-specific versions of Google, Yahoo, Microsoft and Baidu. It also shows the domains that are censored by any one of the four search engines and that domain’s status with regard to the other three engines. In this way we can compare the amount of censored URLs per search query across all four search engines as well as that build a list of censored domains and compare th level of censorship across all four search engines.

Magnify: A Google-Google, Yahoo-Yahoo comparison

This component focuses on two of the search engines that have comparable censored and “uncensored” versions: Google and Yahoo. Microsoft’s “global” search engine in English contains very few Chinese sites and cannot really be compared to their Chinese version. Even other versions such as Hong Kong and Taiwan have such drastically different results when compared to the Chinese version making it a difficult fit for this model of testing. (At this time Baidu Japan has not been sufficiently investigated but it may offer an opportunity for comparison with Baidu China.)

The data collection for section focuses on a direct comparison between (in Chinese)/ and (in Chinese) and It expands upon the collection of censored sites and pages by looking at the overlap of returned pages – pages that appear in the results set for the same query for the same number of results in both search engines as well as indexed pages. It also tracks which sites are hosted in China or end in a .cn domain suffix.

Organized in this way the results raise questions regarding the nature of censorship process as well a the censored content. In terms of process, critical questions have been frequently posed concerning the specificity of the censorship requirements communicated to these search engines by the Chinese government. Are search engines given a list of keywords or a list of web sites that they are to censor? Or, is there just a general reference type of content leaving search engines to infer what exact content to block? How significant are the censored web sites since they only represent a small fraction of indexed sites? How frequently are users search results censored in relation to the topics they search for? Which specific web sites are actually censored? What type of web sites are censored?

In an effort to provide some insight regarding the question of process, the project will measure the overlap between all the search engines as well as subsets that are functionally similar (Google/Microsoft, Yahoo/Baidu). Overlap refers to the sites that are censored by multiple search engines. Overlap is analyzed in two ways: the first focuses on sites that are censored by all search engines tested, the second focuses on search engines that censor using similar mechanisms. While this allows for a comparison among search engines it also acts as an indicator of whether the search engines are responding to specific blocking requests, usually associated with an official order, or a general determination on the part of company, perhaps based on topic areas provided by officials.

Since the total number of censored sites is likely to relatively small compared to the total number of indexed sites , this project proposes a measure of significance in order to show just how important the censored sites are in relation to those displayed to the user. Significance refers to the the number of top ten sites returned from an uncensored search engine that are censored in the China-specific version in relation to those that are either hosted in China or that end in a .cn domain suffix. China could, presumably, take action against those sites under their jurisdiction without having to resort to blocking. In this context, these sites are considered to be “authorized” and are unlikely to contain information that presents an alternative perspective to that approved by the government. In this component results that are returned in the top ten along with those that are indexed but not displayed in the top ten are distinguished from those that are censored. The significance is demonstrated by the absence of top ten results outside of China’s control among a majority of sites that are within the top ten.

Analyzing the web sites found to be censored is an important indicator of the type of content that the government of China wants to block (or of the interpretation of this interest by the search engine companies). Content refers to the type of websites that are targeted for censorship, not the content of individual articles contained within them. This is accomplished through the creation of categories to which censored sites are assigned. This component is the most problematic for automatic determinations. Web sites could be classified using various services that provide categorized URLs but the results may be less than desirable. To operationalize this component properly likely requires, as suggested by Rebecca Mackinnon, analysis by “a team of near-native Chinese speakers who are highly tuned-in to what the sensitive media topics.” Thus this component remains the least developed aspect of the project.

Degrading Transparency: Comparing Google, Yahoo and Microsoft

Google, Yahoo! and Microsoft all maintain versions of their search engines for the Chinese market that censor political content. One of the key issues that emerged concerned transparency. In 2006, all three search engines, following Google’s lead, introduced a message that informed user when the results of their searches were censored. The presence of a mechanism of notification is a critical component of transparency. This notification informs users that their search results have been censored and indicates, to a certain degree, the reason (often unspecified “local law”) why based on what the user searched for. The message appeared only when the user’s results were censored and thus it was possible to connect the censorship to specific keywords or websites.

By 2008 the level of transparency has decreased. While Google’s censorship notification has remained essentially the same as it was in 2006, Yahoo! and Microsoft have altered the way in which users are notified of censorship. Yahoo! has put its censorship message at the bottom of every page regardless of whether results are censored or not, in effect de-linking the censorship notification from the results. Microsoft has removed the text completely and buried the censorship notification with a separate “help” page. These developments represent a significant degrading of transparency and accountability.

By removing or hiding the placement of the censorship message, which is vague to begin with, users may be unaware that their results have been censored and by de-linking the censor message from what the user actually searched for the topics and websites that are censored remain hidden from the user. The de-linking of the censorship message from the search results impacts the ability to determine what precise sites and “key words” are being censored.

The presence and placement of a censorship notification, along with the specificity of its content and its connection to the results, is an integral component of transparency. The specificity of the reason why content has been removed is an important component that is lacking in the case of China. In other cases, Google has cited specific laws, such as the DMCA, and other legal documents with which they must comply and reported the information, to some degree, to Chilling Yahoo maintains a list of sites its censored for copyright violations. However, in the case of censored political content in the case China nothing other than a reference to “local law” has been provided.

The presence of a notification that is directly connected to the results (notification appears only when content is actually removed in relation to what the user searches for) positively impacts the ability to accurately identify censored website and restricted keywords. When such notifications are either absent or disconnected from the results (for example, a notification that appears on every page regardless of whether results are censored or not) the ability to determine censored sites with a high degree of confidence diminishes as sites may simply not be indexed by the search engine. Therefore the notification is critical not only for informing users but also for the monitoring process.

June 26, 2006
Engine Presence Placement Specificity Connection Screenshot
Google Yes High
Notification is placed under results
Results removed to comply with local law
Notification only appears when results are censored
Yahoo Yes High*
Notification is placed under results
Results removed
Yes* screenshot
Microsoft Yes High
Notification is placed under results
Results removed, link to “help” page that mentions local law
Yes screenshot

* Yahoo China’s web crawlers operate from within China, behind the GFW, therefore sites that are blocked by China are not indexed by Yahoo (and thus do not need to be censored by Yahoo) leaving only sites that are either not blocked by China or are indexed during periods when there is variation in the capacity of China’s filtering system to actually be censored by Yahoo. The behaviour documented here refers to sites indexed by Yahoo but subsequently censored, not sites that are not indexed by Yahoo at all.

January 25, 2008
Engine Presence Placement Specificity Connection Screenshot
Google Yes High
Notification is placed under results
Mentions “local law”
Notification only appears when results are censored
Yahoo Yes Medium
Notification is placed at the bottom of every page
Mentions “local law”
No screenshot
Microsoft Yes** Low
A link to a separate “help” page which contains a link to section that contains the notification
A link to a separate “help” page which contains a link to section that mentions “local law”
No screenshot

** There is no notification on the actual page that results the search results. The user must click a “help” page and then navigate to yet another section that state that results may be removed in compliance with local law. the notification mentions pornography as a possible reason, no mention is made of political content.

Presence: The presence of a form of notification that informs users that results may be censored.
Placement: The location of the censorship notification message, particularly its placement in relation to the results.
Specificity: The extent to which users are informed about specific laws, orders and/or regulations leading to censored results.
Connection: Notification appears only when content is actually removed in relation to what the user searches for making it possible to determine which specific web sites and keywords have actually been censored.

(The versions of the search engines tested are the specific version for China. Google ( and Microsoft ( have their servers located outside of China and are tested directly while Yahoo’s ( servers are hosted in China and are tested from inside China. This is necessary to test the search engines without interference from China’s filtering system.)

This is the start of an effort to more systematically monitor transparency over time so I am asking for feedback. Is this information useful? In what ways can it be improved?

Canada, Copyright & Filtering

The Globe and Mail has picked up the story but suggests that filtering for copyright reasons is unlikely:

“Canadian ISPs have been defiant,” said Mark Tauschek, a senior networks and telecom research analyst with Info-Tech Research Group. “They have refused to co-operate. They have said the Internet is an open network and they aren’t going to police the content that goes across it … unless there is criminality involved, they won’t cough up information or necessarily block content.”

What’s interesting here is “unless there is criminality involved.” See, the major ISP’s already filter URLs that contain images of child abuse and may soon be expanding into other issue areas. The filtering technology is in place, it can be extended further. The issue here is that ISP’s don’t want to be in a position of judging content, they don’t want to rule on whether something is criminal or not, but should that responsibility be delegated to some legitimate authority they don’t seem to have any problem with filtering. It seems that filtering for reasons of copyright is not likely to be happening anytime soon. Still, it is an issue worth paying close attention to, as mission creep generally follows the implementation of filtering. It is also worth following closely due to the fact that other countries, particularly the U.S. and Europe are also moving in the direction of filtering for copyright reasons.

Using a technique similar to that of the GFW of China, Comcast is interfering with bittorrent and other traffic. Other ISP’s in the U.S. are also considering implementing filtering. An ISP in Denmark, TDC, blocked to comply with a legal ruling. There have been proposals to implement filtering for copyright reasons in Belgium, Norway, France and other European countries. While the EFF reports that proposed Amendments put before the EU’s Committee on Culture and Education, which included ISP filtering, have been withdrawn or voted down they caution that there may still be attempts to introduce such language before the actual Parliamentary vote.

Will 2008 become the “Year of the Filters“?

Canada: Copyright Lobby Wants Filtering?

In a meeting with the editorial board of the Ottawa Citizen the Canadian Copyright Lobby indicated at several times that they support ISP filtering. Part of the reasoning is based on the belief that consumers say “if you made it impossible for me, if you stopped me, I would just get on with my life and yeah I would return to the market place and I’d buy things.” (28:26) As Prof. Michael Geist notes:

Henderson cites with approval several initiatives to move toward ISP filtering of content, pointing to a French report, comments from the UK that such legislation could be forthcoming, and the AT&T negotiations in the U.S.  Later in the conversation, the group is asked what their dream legislation would look like.  The first response?  ISP liability, with the respondent pointing to Belgium as an example of an ideal model (“the file sharing issue will go away there as ISPs take down people”).  Last summer, a Belgian court ordered an ISP to install filtering software to identify and block copyrighted content (the decision is currently being appealed).

Some other interesting notes from the conversation include the persistent attempts by the Copyright Lobby to highlight the fact that they do not like the changes they want made to the Copyright Act to be referred to or compared to the U.S. DMCA despite the fact that a version of the DMCA is in fact what they want. To accomplish this they continually refer to WIPO, arguing that Canada should just implement WIPO.

There’s an interesting exchange concerning Fair Use rights in which a question is asked concerning how someone would use a 8 second clip of a half-hour show on a blog if the clip is encrypted (DRM protected). The response was a somewhat hostile attack on the person who asked the question concerning an assumption that the Government will somehow outlaw fair dealing which is quite odd since they are explicitly lobbying for an anti-circumvention clause which would outlaw fair dealing in the case presented in the question. It is too bad the questioner did not pursue this line of question more avidly.

As Geist points out, the principles that advocates of fair Copyright want are not necessarily at odds with interpretations of WIPO. WIPO provides for Limitations and Exceptions and even has a document that discusses many such limitations. It is clear that simply ignoring the consequences of implementing new measures, such as anti-circumvention, will leave many unanswered questions regarding Fair Use/Fair Dealing which is why Fair Copyright for Canada wants explicit protections put in place.

Index On Censorship: Evasion Tactics

The journal Index on Censorship has published an article I wrote. In it I argue that there is a failure to recognise Internet censorship and surveillance as a growing global concern. There is a tendency instead to criticise the most infamous offenders-notably China and Iran-and to overlook repressive practices elsewhere. There is, however, a growing resistance to Internet censorship and surveillance, although it is often characterised as a struggle confined to dissidents in a few select authoritarian regimes.

Battles are being fought all over the globe, while the development and use of technologies that protect privacy and make it possible to circumvent censorship are rapidly increasing. The same tools helping dissidents to evade censorship in repressive countries are also being used by citizens in democratic countries-to protect themselves from unwarranted Internet surveillance. Focusing on the global character of both the practice of Internet censorship and surveillance, as well as the resistance to it, provides for both a better understanding of this important trend as well as for the possibility of creating global alliances to combat its spread.

The full article is available below.

More… »

A Few Important Echoes

Do you have any idea who last looked at your data? Seth Finkelstein brings up some some great points in this article but the one I want to focus on concerns the use of privacy protecting technology:

Note that while it’s a common recommendation to use technical means to protect one’s privacy (such as the “Tor” anonymity system, at, such measures are frequently not workable for any but the most knowledgeable and dedicated people. They are often inconvenient and shift a burden on to citizens to be constantly on guard, as opposed to not requiring such guarding in the first place. Using privacy/anonymity programs is good advice, but in overall terms, a bad solution.

I think the point is well taken. Not only should we be making these technologies easier to use (and I think the Tor folks doing so) but we should also recognize that the problem is embedded in a host of other issues. Technology may help us in the short run, but it does not solve the problem. (Oh, and I too like the phrase Seth coined “The price of total personalisation is total surveillance.”).

Catspaw also picks up on a similar theme in response to esquire’s nomination of psiphon as one of the six ideas that will change the world.
She writes:

I’m glad that the issues around internet censorship are getting mainstream attention, as every additional mention helps, but I worry when software programs like Psiphon are advertised as a magic bullet that’s going to make the problem go away. It won’t. This is a complicated issue with very deep social, political and legal structures supporting the censorship, and no piece of software is going to be able to counter that; it’s not just a technical issue.

Times are hard for Iran’s online free-speech pioneer

There is a nice article about Hossein Derakhshan in the Ottawa Citizen. It documents his shift in thinking and the troubles it has caused him. back when his blog was shutdown few of his former allies supported him.What changed? Hossein became very concerned about the demonization of Iran, a possible attack on Iran, and the manipulation of human rights issues to support the former.

All this has left him isolated from the community of politically active expatriate Iranians who formerly supported him. Some bloggers have removed links to his blog. Others have actively urged readers to boycott him. Interview requests from western-based Iranian media have dried up, as have invitations to ex-pat events and panel discussions.

It’s quite a change for someone once widely viewed as a free-speech techno-hero.

A while back Hossein shut down the site that he was running that was focused on Internet censorship in Iran as a protest against the use of the issue to demonize Iran. He wrote:

Internet censorship exists in Iran, as it does in many other parts of the world, especially in the Middle East.

But it has recently become another pretext for the United States and its allies to further demonise and delegitimise the government of Iran.

This reminded me of an earlier case regarding China, “The Great Chinese Censorship Hoax“. Two Chinese bloggers closed their blogs and waited for the news media, bloggers and anti-censorship groups to assume, which they did, that the government shut the blogs down. one of the bloggers involved stated:

“I just wanted to make fun of Western journalists? [content] doesn’t need to be serious on the Internet. I don’t like it that Western media take a distorted view of China, though China does have problems,” Wang told Interfax in an emailed statement, “I thought that if I closed my blog, it would stir their imagination and then they would begin blah blah. It really is as expected. So let’s they have an April Fool’s day in advance.”

These are only two cases but I’m wondering if these cases are a signal of an incubating trend.

China: Media Shift

I thought it might shift.

US-made ‘censorware’ ends up in iron fists

CS Monitor reports:

The software companies involved sell this technology primarily to private companies in the US and abroad. Companies use these tools to keep employees from accessing pornography sites and websites infected with viruses.

Repressive governments also turn to these American systems, not only to filter out porn and viruses, but also to block political, religious, and other websites.

China not blocking RSS/Feeds

EDIT: the focus here is on the fact that China is not dynamically blocking ALL RSS Feeds, however, feeds hosted on already blocked sites are, of course, also blocked.

This article claims that RSS feeds are being blocked in China.

More recent reports tell us that the PSB appears to have extended this block to all incoming URLs that begin with “feeds,” “rss,” and “blog,” thus rendering the RSS feeds from many sites—including ones that aren’t blocked in China, such as Ars Technica—useless.

I’ve tested and they are not blocked.

As Danwei points out “Ars Technica feed are inaccessible in China because it is run through Feedburner’s server (, which is blocked.

GV Advocacy has a nice round-up here.