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Frequent Slashdot contributor Bennett Haselton writes "Tunisia's high court will decide on Wednesday whether to allow censoring of websites containing pornography or 'calls to violence.' It's disappointing that censorship continues in post-revolutionary Tunisia, but it's enough of an improvement over the old regime, that anti-censorship cyber-activism efforts would probably best be spent on helping other countries." Read on for Bennett's analysis.

In Tunisia, where dictator Zine El Abidine Ben Ali was ousted one year ago amid hopes for a new era of freedom, the high court will decide on Wednesday whether to censor foreign pornographic websites in accordance with local law. Facebook pages that "call for violence" may also be blocked. Conveniently, all the machinery for censoring the Internet in Tunisia is already in place, having been installed under Ben Ali's dictatorship for the purposes of censoring and spying on Tunisian citizens (and, for a while, phishing their Facebook passwords). The irony recalls the situation in Iraq in 2009, when the government announced plans to start censoring foreign websites -- to which Iraqi citizens complained that they thought censorship would end with the fall of Saddam's regime. Actually, apart from the three outlier countries of Turkey, Israel and Lebanon, pornography remains illegal in every Middle Eastern country (and some conservative African nations), including the recently "liberated" ones including Egypt, Iraq and Tunisia. (Although, Iraq's street market in pornography thrives as long as the police have better things to do.)

I'm against such censorship in principle -- I think that even the right to publish and access pornography counts as a fundamental human right. But I think we have to take what progress we can get, and censoring just pornography and calls to violence, is a big improvement over censoring pornography and dissident political speech, which is the norm in most non-"liberated" Middle Eastern countries like Syria, Iran, and Saudi Arabia. Syria blocks foreign opposition sites like All4Syria.info, Iran blocks Facebook and YouTube to keep dissidents from posting or viewing anti-government material, and Saudi Arabia blocks Reporters Without Borders and filters the Amnesty International report on human rights in Saudi Arabia (but not the rest of the Amnesty International site!).

Saudi Arabia blocking the Amnesty International report on human rights in their country (while leaving the rest of the site unblocked), in particular, seems like the kind of thing that a government would do more as a "fuck you" to human rights activists, than a means to achieve a practical goal. For one thing, most of the facts in the human rights report about Saudi Arabia -- about sex discrimination and lack of political and religious freedom -- are already well known to the people who live there. And secondly, what percent of the citizens of a country would ever read the Amnesty International report on human rights in that country, even if it were not blocked? How many Americans even know that Amnesty puts out an annual report about human rights violations in the United States? So it seems more like a symbolic move to remind everyone who's in charge. For all the disappointment in the lack of progress for free speech in post-"liberation" countries, the non-"liberated" ones are indeed worse.

As for the Tunisian proposal to censor "calls to violence", I wouldn't always be against that, even in principle. In most countries, direct incitements to violence can be considered illegal (it depends on what you say and, of course, on what judge you get). In a developing country rife with ethnic tensions, even greater restrictions on calls to violence could be justified. When you finally watched Hotel Rwanda , weren't you hoping someone would bust in on that radio DJ telling everyone to kill Tutsis in the middle of a civil war, and blow him to hell? The biggest problem with a rule against "calls to violence" is that the government could stretch the definition to silence political speech. But it's possible to keep that kind of abuse in check, as has mostly been achieved in the U.S. For that, what you need is an independent judiciary, not an abolishment of all rules against calls to violence.

So the free-speech situation in "liberated" Tunisia may be nothing to write home about, but it sounds much better than it used to be, when writing home to complain about it could get you arrested. A Wall Street Journal article from July 2011 describes how, under Ben Ali's dictatorship, Tunisian cyber-activist Slim Amamou had been imprisoned and abused by the police for calling for peaceful demonstrations. Post-revolution, he was freed and asked to join the interim government, where the strictest restriction placed on him was to "stop sending Twitter messages during internal government meetings to his 25,000 followers". They may not have their porn, but that's still progress.

Of course, if someone in Tunisia wants to circumvent the government filters (using tools like proxy sites, VPNs, Tor, UltraSurf, Psiphon, etc.) and get to a porn site, more power to them. I just wouldn't make it a priority to set aside resources to help them get it. Not while there are Iranians who need help getting around the latest restrictions blocking them from Facebook and Gmail.

Two caveats. First, if someone wants to sell circumvention services to Tunisians who just want to get around the porn blocker, that doesn't count as "setting aside resources", so that's a perfectly noble endeavor. In fact, given the economies of scale in the circumvention business, selling to Tunisians could help to bring the price down for other users, including users in countries like Saudi Arabia where the government does engage in political filtering, and where circumvention services could be a tool for social change. Second, providing circumvention services (free or paid) to Tunisians, does probably make it less likely that the new government would revert to political censorship, knowing that many of its citizens have the tools to beat it, even if those tools are only currently used to access porn sites. So to that extent, setting aside resources to provide circumvention services in Tunisia might be a worthwhile cause.

Still, I think it's a lot less important than using circumvention tools to fight political censorship in truly autocratic countries like Iran. For the next generation of proxy servers that I'm rolling out, I'm working on setting aside some of them just for Iranian IP addresses. Even if Iranians just use them to get on Facebook, that's still contributes more to advancing the cause of social democracy, than Tunisians using them to get on Playboy.

Slashdot regular contributor Bennett Haselton wrote in this week to say that "The proposed "Telex" anti-censorship system could technically work, but unless I'm missing something, it would more cost-effective to spend the same resources on fighting censorship using existing technologies." His essay on the subject follows.

Professor Alex Halderman published a paper in July describing a new anti-censorship system called Telex, whereby users in censored countries could request banned websites by sending an encrypted request to an SSL-enabled website (i.e., a Web address beginning with https://) outside of their country -- even if the owner of the SSL-enabled website is not participating in the scheme. Since encrypted communications usually contain some random variation, that random variation can be used to embed hidden messages, which can then be decoded by any third-party observer who intercepts the communication and knows how to decode the hidden message. The third-party observer still cannot decode the original encrypted communication between the end user and the SSL-enabled website -- SSL is designed to be unbreakable by all but the intended recipient -- but the observer can decode the "side message" that was designed to be intercepted in transit. So a Telex-enabled router, in the process of passing the communication along, would notice the hidden request for a banned website, and pass the requested content back to the original user.

By analogy, suppose Mrs. Smith wants to send a letter to a friend. Mrs. Smith knows the letter will be sealed, and supposedly unopenable by the postman. But Mrs. Smith also has many choices of colored envelopes to use, and she has agreed with the postman on a color-coded system -- red for "Meet me tonight at the Motel 6", blue for "Not tonight, he suspects something" -- that the postman can "decode" when he picks up the envelope for delivery. The choice of envelope color is the "random variation" inherent in the sending of the message, which the message sender can use to send a "side message" to anyone who passes it along and who knows the system. The postman -- who is analogous to the Telex-enabled router -- has no access to the original sealed message inside the envelope, but he understands the side message just fine. (A Telex user may have no control over what routers their messages pass through, though, so they simply have to hope that there are enough Telex-enabled routers on the Internet that one of them will pick up the message and decode it. Imagine many different amorous mail carriers in the Postal Service, and any one of them who finds the colored envelope will be happy to show up at the appointed time, if Mrs. Smith is not picky.)

The novel feature of Telex is that it would not require the cooperation of the owner of the SSL-enabled website in order to work. You could send an encrypted communication to any website -- https://www.paypal.com/ for example -- and any Telex-enabled routers along the pathway traveled by the connection, would be able to decode the embedded message hidden in the randomness of the encryption. By contrast, for a user to make use of a typical proxy website like Vtunnel, the owner of the Vtunnel website has to set up the site as a proxy; this means the supply of such sites is limited to those websites whose owners have installed proxy software, and the censors have a greater chance of finding and blocking them all. Telex, on the other hand, would continue to work as long as the user in the censored country was able to access any SSL-enabled website, as long as their request happened to pass through a Telex-enabled router.

So far, so good. But this would presumably require an investment of at least several million dollars by any major backbone provider who wanted to try it, by re-configuring their major routers to speak the Telex protocol, and then potentially hundreds of millions of dollars for a sustained long-term effort. (As Halderman says, "We like to envision this technology as a possible government-level response to government-level censorship.") So here's my question: If any backbone provider (or government entity) wanted to go to that trouble to support the cause of fighting Internet censorship, why wouldn't it be much more straightforward for them to just set up proxy websites themselves?

Professor Halderman didn't respond to my inquiry on that point. The Telex FAQ notes that censorious governments can easily block new proxy sites once they find out about them. But in many censored countries, most proxy sites are not blocked, either because the government isn't trying, or they can't keep up. In China, hardly any proxy sites are blocked at all, as the government seems to put more of their resources into suppressing local dissent directly. Meanwhile in Iran, the censors do put more resources into actually blocking proxy sites -- but because Iran is on the U.S. State Department's embargo list, Iranian censors can't buy Internet censoring software from U.S. companies, so they have to find and block the sites themselves. As a result, newly released proxy sites often stay unblocked longer in Iran than they do in other Middle Eastern countries that use U.S.-made blocking software. Meanwhile, Saudi Arabia, for whatever reason, doesn't seem to block proxy sites at all for the time being. (Saudi Arabia is a strange outlier, since most conservative Islamic countries that filter the Web, also block proxy sites as well. It's not clear why Saudi Arabia doesn't.) So if a government or a philanthropist wants to help the cause of fighting censorship, just set up some proxy sites and pay to keep them running -- and you'll be helping the residents of all of those countries right away, for starters. This is in fact what Voice of America (through their various proxy programs) and the founders of UltraSurf (a privately funded network of anti-censorship servers) have been doing all along.

Even in the case of countries like U.A.E. and Yemen that are reasonably quick at finding and blocking proxy sites (as a result of using Western-made blocking software), the most cost-effective way to help these users is probably to set up more proxy sites, hosted at different locations and with perhaps with legitimate-looking "decoy" content, so that U.S. censorware companies can't keep up. My experience has been that the more money you spend (using unique IP addresses, buying .com domains instead of cheap .info ones, and setting up lots of proxies so that each one is sent to only a subset of your target audience), the longer the proxy sites last. You can also use proxy-like services (such as Tor, Hotspot Shield and UltraSurf) to route traffic through dedicated servers, to circumvent censorship in a way that is more transparent and convenient to the end user.

In short, existing proxy sites (and proxy-like services) do the job pretty well for many censored countries, and a massive cash expenditure on setting up more proxies (equivalent to the cost of setting up the Telex system) would probably be enough to demolish all other national filtering schemes completely. The software and tools to run proxy sites have already been tried and tested; all it takes to run them is money. Telex, by contrast, would require backbone providers to alter the architecture of their systems -- which means large-scale testing, isolation of any problems that arise, and countless other potential headaches. And that's not even counting the fact that censorious countries might detect which backbone providers are using Telex, and block all traffic from their countries to any sites hosted on those networks.

So I think Telex is a brilliant technical achievement, and I'd be happy if it got deployed, but I'd be scratching my head as to why the backbone providers (or the government, or whoever sponsored the effort) decided to kill a gnat with a flamethrower. I deal in flyswatters for a living, and they get the job done.

Slashdot regular contributor Bennett Haselton wrote in this week to say that "The proposed "Telex" anti-censorship system could technically work, but unless I'm missing something, it would more cost-effective to spend the same resources on fighting censorship using existing technologies." His essay on the subject follows.

Professor Alex Halderman published a paper in July describing a new anti-censorship system called Telex, whereby users in censored countries could request banned websites by sending an encrypted request to an SSL-enabled website (i.e., a Web address beginning with https://) outside of their country -- even if the owner of the SSL-enabled website is not participating in the scheme. Since encrypted communications usually contain some random variation, that random variation can be used to embed hidden messages, which can then be decoded by any third-party observer who intercepts the communication and knows how to decode the hidden message. The third-party observer still cannot decode the original encrypted communication between the end user and the SSL-enabled website -- SSL is designed to be unbreakable by all but the intended recipient -- but the observer can decode the "side message" that was designed to be intercepted in transit. So a Telex-enabled router, in the process of passing the communication along, would notice the hidden request for a banned website, and pass the requested content back to the original user.

By analogy, suppose Mrs. Smith wants to send a letter to a friend. Mrs. Smith knows the letter will be sealed, and supposedly unopenable by the postman. But Mrs. Smith also has many choices of colored envelopes to use, and she has agreed with the postman on a color-coded system -- red for "Meet me tonight at the Motel 6", blue for "Not tonight, he suspects something" -- that the postman can "decode" when he picks up the envelope for delivery. The choice of envelope color is the "random variation" inherent in the sending of the message, which the message sender can use to send a "side message" to anyone who passes it along and who knows the system. The postman -- who is analogous to the Telex-enabled router -- has no access to the original sealed message inside the envelope, but he understands the side message just fine. (A Telex user may have no control over what routers their messages pass through, though, so they simply have to hope that there are enough Telex-enabled routers on the Internet that one of them will pick up the message and decode it. Imagine many different amorous mail carriers in the Postal Service, and any one of them who finds the colored envelope will be happy to show up at the appointed time, if Mrs. Smith is not picky.)

The novel feature of Telex is that it would not require the cooperation of the owner of the SSL-enabled website in order to work. You could send an encrypted communication to any website -- https://www.paypal.com/ for example -- and any Telex-enabled routers along the pathway traveled by the connection, would be able to decode the embedded message hidden in the randomness of the encryption. By contrast, for a user to make use of a typical proxy website like Vtunnel, the owner of the Vtunnel website has to set up the site as a proxy; this means the supply of such sites is limited to those websites whose owners have installed proxy software, and the censors have a greater chance of finding and blocking them all. Telex, on the other hand, would continue to work as long as the user in the censored country was able to access any SSL-enabled website, as long as their request happened to pass through a Telex-enabled router.

So far, so good. But this would presumably require an investment of at least several million dollars by any major backbone provider who wanted to try it, by re-configuring their major routers to speak the Telex protocol, and then potentially hundreds of millions of dollars for a sustained long-term effort. (As Halderman says, "We like to envision this technology as a possible government-level response to government-level censorship.") So here's my question: If any backbone provider (or government entity) wanted to go to that trouble to support the cause of fighting Internet censorship, why wouldn't it be much more straightforward for them to just set up proxy websites themselves?

Professor Halderman didn't respond to my inquiry on that point. The Telex FAQ notes that censorious governments can easily block new proxy sites once they find out about them. But in many censored countries, most proxy sites are not blocked, either because the government isn't trying, or they can't keep up. In China, hardly any proxy sites are blocked at all, as the government seems to put more of their resources into suppressing local dissent directly. Meanwhile in Iran, the censors do put more resources into actually blocking proxy sites -- but because Iran is on the U.S. State Department's embargo list, Iranian censors can't buy Internet censoring software from U.S. companies, so they have to find and block the sites themselves. As a result, newly released proxy sites often stay unblocked longer in Iran than they do in other Middle Eastern countries that use U.S.-made blocking software. Meanwhile, Saudi Arabia, for whatever reason, doesn't seem to block proxy sites at all for the time being. (Saudi Arabia is a strange outlier, since most conservative Islamic countries that filter the Web, also block proxy sites as well. It's not clear why Saudi Arabia doesn't.) So if a government or a philanthropist wants to help the cause of fighting censorship, just set up some proxy sites and pay to keep them running -- and you'll be helping the residents of all of those countries right away, for starters. This is in fact what Voice of America (through their various proxy programs) and the founders of UltraSurf (a privately funded network of anti-censorship servers) have been doing all along.

Even in the case of countries like U.A.E. and Yemen that are reasonably quick at finding and blocking proxy sites (as a result of using Western-made blocking software), the most cost-effective way to help these users is probably to set up more proxy sites, hosted at different locations and with perhaps with legitimate-looking "decoy" content, so that U.S. censorware companies can't keep up. My experience has been that the more money you spend (using unique IP addresses, buying .com domains instead of cheap .info ones, and setting up lots of proxies so that each one is sent to only a subset of your target audience), the longer the proxy sites last. You can also use proxy-like services (such as Tor, Hotspot Shield and UltraSurf) to route traffic through dedicated servers, to circumvent censorship in a way that is more transparent and convenient to the end user.

In short, existing proxy sites (and proxy-like services) do the job pretty well for many censored countries, and a massive cash expenditure on setting up more proxies (equivalent to the cost of setting up the Telex system) would probably be enough to demolish all other national filtering schemes completely. The software and tools to run proxy sites have already been tried and tested; all it takes to run them is money. Telex, by contrast, would require backbone providers to alter the architecture of their systems -- which means large-scale testing, isolation of any problems that arise, and countless other potential headaches. And that's not even counting the fact that censorious countries might detect which backbone providers are using Telex, and block all traffic from their countries to any sites hosted on those networks.

So I think Telex is a brilliant technical achievement, and I'd be happy if it got deployed, but I'd be scratching my head as to why the backbone providers (or the government, or whoever sponsored the effort) decided to kill a gnat with a flamethrower. I deal in flyswatters for a living, and they get the job done.

Slashdot frequent contributor Bennett Haselton writes a piece advocating for Pop-Ups and even more obtrusive advertising. But not for the reasons you might think. He says "Annoying pop-up ads have been a great friend to Internet freedom, by enabling the operation of proxy sites that would be too expensive to operate otherwise. With the rising costs of making new proxy sites to stay ahead of the 'censorware' companies, even more intrusive ads could be an even bigger friend to Internet freedom. Got any ideas for how those more intrusive ads could work?" Clicky clicky below to read his point.

Most news and information websites carry advertisements, but usually not more than one pop-up ad, if they have pop-ups at all. This is because the costs of running the sites are low enough that they can usually pay for their costs with revenue from regular ads. Surely the site owners would like the extra money that they could get from pop-ups, if their viewers had nowhere else to go. But if they tried to get away with too many pop-ups on a typical news site, visitors would just leave for their competitors' sites instead. Competition keeps the "prices" — in terms of the ads that you have to view in order to visit a website — low.

By contrast, most proxy sites [that's not a link to one of my sites, so quit yer whining] — sites that you can use to get around Internet blocking, by using a form to type in the URL of the site that you want to access so the proxy site will fetch its contents for you — are festooned with pop-up ads, sometimes on every page load. As I can easily attest, the bandwidth and hardware costs of running a proxy site are sufficiently high that there would be no way to pay for the sites with the revenue from normal banner ads and AdSense blurbs. It's no exaggeration to say that most proxy sites, which enable people to circumvent government filtering in countries like China and Iran (not to mention helping millions of students get on Facebook and YouTube from school), would not exist without the pop-up ads to prop them up. (This may not be true of a proxy site that your high school classmate set up for himself and some friends, but it's true of most proxies created to serve a wide audience.)

Unfortunately it's becoming more expensive to run an effective proxy service that enables users to get around most enterprise filtering programs. If it gets to the point where normal pop-up ads do not bring in enough revenue to pay for the service, we might need a new breed of even more intrusive (and better-paying) ads. More intrusive than the drop-down ads that play noisy videos. More intrusive than the Flash animations that crawl across the screen on top of the words you're trying to read. I'm going to argue that a company that figures out how to run the most intrusive ads of all, could be the new best friend of Internet freedom. But first a note about why the costs are increasing.

Two years ago, I thought the cost of maintaining a proxy site to help people get around Internet filtering, would steadily fall, as bandwidth and processing power got cheaper. But bandwidth and hosting costs didn't drop as much as I had hoped, and the cost of maintaining an effective anti-filtering service has actually gone up, due to some advances made by Internet censoring programs. In 2007, the then-current versions of filtering programs like Smartfilter, Websense, and the 8e6 R3000 would typically only download updates to their blacklists once in the middle of the night. This meant that I could mail out a new proxy site to my proxy mailing list just after midnight, and it would be accessible to the mailing list subscribers all of the following day. (You wouldn't be able to get to them if your local network administrator subscribed to the mailing list and added the new sites to the local blacklist as soon as they came out, but most network admins didn't bother.) As of 2010, though, the latest versions of most enterprise filters are configured to automatically update their lists every hour or two. So to stay ahead of the filters, I have to mail out several sites every morning to different portions of the mailing list, so that the filtering companies generally learn about them and block them at different points throughout the day. Just registering several .com domains every day is not cheap. (GoDaddy sells .info domains for less than a dollar apiece, but this proved to be an ineffective solution because too many censored networks simply block all .info sites.)

There are also the increasing costs of maintaining compatibility with complex sites like Facebook and YouTube. Accessing Facebook through a proxy is still a hit-or-miss proposition. (I steer my users toward accessing the mobile version of Facebook, http://m.facebook.com/ , through the proxy, because it's a stripped-down version built for compatibility with mobile devices, and this simpler version is less likely to break when accessed with a proxy script.) YouTube access depends mainly on whether the latest YouTube plugin for the Glype proxy script is compatible with the current YouTube interface, and likewise can be working one week and broken the next. It's not hard to run a proxy site that provides compatibility with the most popular sites that people want to access, but it takes real work -- you can't just upload the script and forget about it.

(Many users in censored countries also use tools like Tor and UltraSurf to bypass their country's filters, but some of my contacts in those countries say that those tools are often too slow for them, so they end up using proxy sites instead. Since UltraSurf and Tor are free services, funded by donations and staffed by volunteers, the demand for those services can easily swell until they slow down from the overload.)

So what happens if maintaining an effective anti-censorship service becomes too expensive to pay for using just pop-up ads? Well, you could charge money for using your proxy site, but that brings with it a whole host of other problems. You have to set recurring billing in order to be paid through PayPal or some similar service, and run the risk of your funds being frozen if someone files a crank complaint against you. If one user has a paid account, you have to worry about them sharing the account with their friends or posting the account credentials on a public message board. And there are many proxy operators (including me) who would like to think that the proxies do provide a valuable public service to the world, and wouldn't want to exclude people who can't afford the monthly access fee.

I propose that ads which are even more intrusive than pop-ups -- thus grabbing more of the user's attention and providing more value to the advertiser, thus enabling them to pay more to sites which run the ads -- would enable proxy site operators to fund more of the costs of their operation, and hence would be a Good Thing. The existence of such intrusive ads does not mean that they would suddenly be plastered all over every proxy site. If your user base can be served for a lower cost, then you don't have to "charge" as much (in terms of advertisement intrusiveness) to use your proxy service. Over 90% of the traffic to my proxy sites is to domains that have already been blocked a long time ago by Websense, Smartfilter, Lightspeed, and most of the rest of the censorware companies. Apparently there are a lot of users who are on censored networks and who need proxies, but whose network admins just haven't updated the blacklists in a very long time, or who haven't paid the subscription fee to keep downloading database updates. Since you don't need to register 10 new domain names every day to serve that audience, there would continue to be proxies for those users with less-intrusive ads on them. But the more-intrusive (and higher-paying) ads would also enable proxy webmasters to serve a "higher-end" audience, the ones who need several new sites every day, to stay ahead of the more frequently-updated filters.

I can think of several ways that more intrusive ads might work. My favorite would be a "quiz" model wherein a drop-down advertisement appears in front of the site you're trying to access, consisting of some promotional content, and a little form at the bottom. In order to make the drop-down ad disappear, you have to read the ad and fill in the answers to some one-word questions or multiple-choice questions about the content, to prove you actually read it.

Perhaps I'm biased in favor of this idea because I'm tired of ads that contain splashy graphics and expensively licensed music and never contain any actual information. The only television ad that I can recall viewing in the past year which prompted me to actually buy the advertiser's product, was the Pizza Hut ad announcing that you could get a large pizza with any number of toppings for $10. That's what I want in an ad. I give you $10. You give me a pizza. (And this extra plug for their $10 pizza promotion, can be considered a thank-you to them for running an ad that actually had something to say.) Most ads on TV are far less informative, serving mostly to give a glossy sheen to the advertiser's brand name. Yet these ads are paid for by corporations who do the market research and the focus grouping, so the ads must work. Many economists, including Tim Harford in The Undercover Economist and Steven Landsburg in The Armchair Economist, have explained why companies pay for ads that do nothing except look expensive: Because they prove to the viewer that the company intends to be around for a long time, in order to capitalize on the long-term exposure given to them by the ad. This has become so standard that making an ad which actually gives the user information seems tawdry by comparison. The most ghetto-sounding word in TV advertising is "infomercial".

But I think that some companies could benefit from greater exposure of actual information about their product, just as there are companies that pay for informercials. And if a company like Linksys really wanted to run a splashy ad that contained no actual information, and then make me answer some questions at the bottom like:

Linksys is:
(a) the leading manufacturer of wireless adapter cards
(b) the leading manufacturer of wireless routers
(c) the leading manufacturer of wireless monitoring cameras
(d) all of the above!!!

then that's their prerogative. The quiz-advertisement model only says that advertisers can require users to answer a question before closing the ad; it would be up to the advertiser to decide what question works best. I suspect that the actual-information model would work better for quiz ads, but advertisers could try both and see what works.

There are already some websites that require you to "complete an offer" (i.e. become a customer of some third-party company, at least for a free trial period) in order to use their services, but most proxy sites have so far declined to carry advertisements like these. Evidently their users consider this too high of a price to pay to access a proxy site. Filling out an offer is not just time-consuming, but leaves the door open to future problems -- will they sell your name or your e-mail address? Will they make it hard to cancel your "free trial", and then start billing you? The problem seems to be that there is too large of a gap between the "fees" associated with the two options -- a normal advertisement doesn't bring enough money to the proxy operator, but a complete-an-offer advertisement is such a steep price that most users won't pay it. The "quiz ad" is like a "fee" that falls nicely in the middle -- a smaller time commitment, and your worries are over after you fill in the quiz and hit submit.

If the very thought of such an ad still seems too annoying for words, then I think that objection misses the point. If the revenue from "normal" ads (pop-ups, drop-downs, AdSense widgets) is enough to pay for the operation of a "high-end" proxy service (catering to the people who need several new proxies every day), then such proxy services with "normal" ads will continue to exist. Indeed, anyone who tried running the more annoying "quiz ads" would not be able to get off the ground, because users would flock to the competing proxy sites using normal ads instead. If "high-end" proxy services flourished that were using quiz ads, it would only be because you simply can't provide a high-end service for less money than the quiz ads are bringing in.

It's possible that some advertisers would be reluctant to display ads in a manner that users would continue an annoying obstacle, but I'm not sure that's really a problem. The most intrusive advertisements currently in use on mainstream websites are probably the "premercials" that display before some news videos on CNN.com and other news sites. Unlike drop-down ads which can be closed with the click of a button, the video pre-mercials can't be skipped. Since you're actually expecting the news video to come up immediately when you click the link to start playing the video, you would think that many users would grit their teeth in annoyance upon seeing the "pre-mercial", and transfer that irritation to the advertiser's brand name, but there are so many big-name companies buying those pre-mercials that they must believe it's having a positive effect. So intrusiveness itself doesn't seem to tarnish a brand.

But I don't propose to micro-manage suggestions for how the more intrusive ads would look, or how advertisers should tailor their ads to fit the format. I'm just saying that a new breed of more intrusive ads, even more annoying than pop-ups, might be just what we need to stay ahead of increasingly sophisticated Internet censors. It's still technically quite trivial to release a steady stream of new proxy sites that defeat most Internet filters, but it costs money to buy domains and maintain the service, and the money has to come from somewhere.

Frequent Slashdot contributor Bennett Haselton writes "A simple experiment shows that it's easy to find the IP addresses used by the UltraSurf anti-censorship program, and block traffic to all of those IP addresses, effectively stopping UltraSurf from working. But this is not a fault of UltraSurf; rather, it demonstrates that an anti-censorship software program can be successful even if it's relatively trivial to block it." Read on for Bennett's analysis.
UltraSurf is an enormously popular program used to circumvent Internet censorship in countries like China (as well as schools and workplaces in mostly-free countries like the US, with mixed success). When you run UltraSurf on your computer, it re-routes your outgoing Internet traffic to external IP addresses controlled by UltraSurf, so that it looks to observers (and network censors) as if you are connecting to UltraSurf's IP addresses, rather than a website like YouTube or Facebook that may be banned on your network.

UltraSurf uses a list of thousands of external IP addresses, to make it non-trivial for an adversary to locate all of their IP addresses and block them all. However, using a few steps that would be obvious to many programmers facing the same problem, I did find a way to detect all the IP addresses that UltraSurf connects to, and block all of them so that UltraSurf stopped working. It would not be hard for a government censor operating the filter in a country like China to do the same thing. But this does not mean that UltraSurf's network is likely to collapse any day now; on the contrary, it means that it and similar programs are likely to flourish for years to come, since the censors obviously have other priorities.

Some background information first. Most Internet censorship circumvention tools fall into one of two categories (whose names I have just invented for the purpose of this article):
(1) Self-bootstrapping. If a program is self-bootstrapping, then in a censored country you simply run a copy of the program and it will establish a connection to an IP address outside the country, one of many in a large "cloud" of IP addresses controlled by the software program's publisher. Thereafter, your Internet usage is routed through that connection in order to evade your country's filter. UltraSurf and Tor fall into this category.
(2) Non-self-bootstrapping. To use one of these programs from a censored country, first you have to get a friend in a non-censored country to install the software on their computer (or their webserver, if they have one). Then they give this location (normally in the form of a URL) to their friend in the censored country, and their friend types that URL into their browser to circumvent their country's filtering. Psiphon is the best-known program in this group.

In 2006 I wrote that even though the first category of programs was more convenient to use (not requiring you to rely on a friend in an uncensored country), any program in that category could be blocked by an adversary willing to make only a modest amount of effort: Install the program, see what IP addresses it connects to, block those, see if the program connects to any other backup IP addresses, block those, and so on, until the program runs out of IP addresses to use. There are a few simple countermeasures that designers of a program could take, but they can also be defeated easily.

(For example, if the program randomly chooses an IP address from a large internally stored list, then you just have to run the program over and over until you've found most of the IP address chosen by its random algorithm. A cleverly written program could try to evade this as follows: Pick a set of IP addresses at random from the list, and then "lock in" to that set of IP addresses, so that future runs of the program on that PC will always connect to those IP addresses, ignoring the other ones in the list. This makes it a little bit harder for the censor to pry out all of the IP addresses in the program's internal list. But then you, as the censor, can either (a) run the program repeatedly, but find where the program stores its "locked set" and erase that between each run, so that on future runs the program will keep selecting a different IP address set, or (b) if you can't figure out where the program is storing its "locked set" between each run, then just install the program repeatedly on different machines.)

One way or another, if the program knows what IP addresses to connect to when it bootstraps itself, the attacker can trick the program into revealing all of them. The attacker doesn't even need to reverse-engineer the software to see the set of instructions that it's executing internally; they only need to be able to see the IP addresses that the program is connecting to.

Much later, I was able to reduce this to practice in an experiment on my own machine, using a Perl script, the built-in Windows "netstat" tool to list connections from locally running programs to outside IP addresses, and the "ipseccmd" tool to add new firewall rules blocking those IP addresses. After the script was left running overnight, it had collected and blocked all the IP addresses that UltraSurf apparently used, and on future runs, UltraSurf would display an error message saying that it couldn't find any IPs to connect to.

(Interestingly, netstat also showed that UltraSurf frequently opened connections to www.google.com over SSL -- that is, accessing URLs that would begin with "https://www.google.com/" -- so that traffic between the program and the Google website would be encrypted, and the contents would be invisible to censors in China. When I saw it was doing that, I added an exception to the script so that the Google IP addresses would not be blocked. Perhaps it was submitting search terms to Google in order to find pages that give the location of the latest UltraSurf connection points, or perhaps it was checking a GMail account created by UltraReach that stores messages containing more IP addresses; I didn't reverse-engineer UltraSurf to find out. But even if this was UltraSurf's clever means of obtaining new IP addresses, the system still runs up against the same problem: Any IPs that can be connected to by the UltraSurf client, can also be ascertained by the attacker who watches UltraSurf to see where it connects to, and then blocks those IPs as well.)

Naturally I had mixed feelings about pointing this out publicly, since I agree with UltraReach's goal of providing unfiltered access to users in China and other censored countries. But this idea is sufficiently obvious, that I don't think anything is lost by demonstrating it. There may be programmers interested in creating even more programs to help users in censored countries, and it would be counterproductive for those programmers to believe that existing programs like UltraSurf "magically" evade the censors by using some complex algorithm to hide the IP addresses that they connect to. In fact, the program doesn't conceal the IP addresses that it connects to (how could it?), and it would be straightforward to design and build a new program that did roughly the same thing. We should give UltraReach credit for the right things: they made a tool that provides unfiltered access to millions of people, they made the tool small and easy to use, and they arranged with their partners to subsidize the unfiltered Internet connections at no expense to those end users (although see some caveats, which have been pointed out the Hal Roberts at the Berkman Center, about the price of this "free" access). But the one thing UltraReach did not do is find a way to get around the problem of an attacker installing the problem to see what IP addresses it connects to. That's not a criticism of UltraReach; this is presumably an impossible problem to solve.

(Side note about counter- and counter-counter-measures: If UltraReach does think that censoring countries might try harder to block UltraSurf at some point in the future, they should start releasing different versions of the product every month that use different sets of IP addresses. Release one version for September 2009 that uses one set of IP addresses, then another version in October 2009 that uses another set, and so on. Then if the censors decide in December 2009 to start seriously trying to block all UltraSurf IP addresses, they'll be able to find and block all the IP addresses used by the Dec09 version, just by installing a copy of the program and observing it. But, users who downloaded previous months' versions of the program will be able to continue using their copies. If the Chinese censors wanted to find and block the IP addresses used by preivous months' copies of UltraSurf, they would have to either (a) figure out how to distinguish UltraSurf traffic from other Internet traffic, not an easy thing since UltraSurf uses encrypted traffic on port 443, the same port used for encrypted Web traffic, or (b) obtain copies of the program that users had downloaded in previous months, which is no longer as trivial as simply observing the current version of the program. The more often UltraReach swaps out a new version of UltraSurf that connects to a new set of IP addresses, the harder it will be for the Chinese censors to find all the sets of IPs used by previously released versions. However, once the Chinese censors start trying seriously to block UltraSurf, even though the trick just described will allow previous downloaders of the program to continue surfing freely, all new users who download the program after that point, can be easily blocked -- because the Chinese censors can just watch how often a new version of UltraSurf is made available for download, and block the IPs used by that copy.)

But I think the fact that the Chinese have not done this reveals something usually overlooked about the nature of the anti-censorship arms race. The situation is frequently cast as a battle between the evil geniuses who run the government filters and the good geniuses who write the software to get around the filters, while the grateful citizens of the censored country are the beneficiaries. But if the government censors haven't even done some simple experiments like this in order to block UltraSurf, they must not think it's a high priority to stop the program from working. This in turn suggests that the number of people using UltraSurf in a country like China, while large in absolute numbers, don't constitute a large enough proportion of the population to worry the government. Presumably either the ideas leaking in through an unfiltered Internet are not reaching a large enough proportion of the population, or the ideas are not expected to take hold in enough people's minds to reach a tipping point that causes a problem for the ruling party.

It's not that the Chinese censors don't care about controlling the Internet and the effect that it has on their citizens' thinking. The Chinese have reported fielded a droid army of about 50,000 cubicle drones to help fight Internet propaganda battles, such as drowning out anti-government posts on public forums. Why would they spend such enormous efforts to generate forum posts, but not make the effort to find and block all UltraSurf IP addresses? Because the battlefront is about defaults. If the user tries to access a site and it's blocked, then only a tiny proportion will make a significant effort to circumvent the block. (The exception would be when an extremely popular site like YouTube is blocked; operators of Web proxy sites report that during these periods, they get so much traffic from Chinese users trying to view YouTube videos, that the servers often crash.) Similarly, if users see that 90% of the posts on a given forum are on one side of the issue, then they're more likely to think that's the majority viewpoint (whether they agree with it or not). Hence the usefulness of the army of 50,000 to invade forum threads. Defaults matter; would Internet Explorer have ever displaced Netscape's browser (kids, ask your parents) if it hadn't been the default browser in all versions of Windows?

So the moral for any would-be designers of new anti-Internet-censorship tools, is not to worry too much about whether there's a theoretical way (or even a practical way) that the censors could shut the tool down. UltraSurf became enormously popular without solving that problem, and perhaps another tool could as well.