BEFORE he was jailed, few people had heard of Wu Xiangyang. But when news of his conviction appeared in a state newspaper in late December, internet users across China took note. A small trader from the southern province of Guangxi, Mr Wu’s crime was to sell cheap and commonly used software that enables people to circumvent China’s draconian internet controls. His five-and-a-half-year prison sentence is the toughest-known penalty imposed for such “illegal business”.

Motivated Chinese have long found it fairly easy to acquire such software, which provides access to what is known as a virtual private network (VPN). Through this kind of connection, a user in China can reach the thousands of websites that are blacklisted by the government—including almost all Google services, many news sites and most foreign social networks. Many people use VPNs several times each day to jump the country’s “great firewall”, as its system of online censorship is often called in English (Chinese netizens have adopted the acronym GFW). Foreigners in China depend on VPNs to reach sites they routinely need: everything from Gmail and Dropbox to Facebook and Instagram.

Many observers believe that the great firewall’s porousness is a feature, not a bug—that its architects see benefit in a barrier that does not completely alienate entrepreneurs, academics and foreign residents, but which most Chinese web-users will not have the energy, or the finances (VPNs usually require subscriptions), to surmount. But doubts are growing about this interpretation. For the past year the government has been trying to make it harder to find, and use, VPNs—the most common form of firewall-leaping tool. Mr Wu’s punishment was clearly intended as a harsh warning to others in China not to try selling such services to ordinary consumers. Speculation is growing that even tougher curbs will be imposed in 2018.

Such fears may prove unwarranted, but the government has been doing little to allay them. Limiting the sale and use of VPNs is one aim of a “clean-up” of the internet industry that began last year and is supposed to be complete by the end of March. Several popular providers based in China have folded under government pressure. Those that remain are aimed at business users. Mr Wu’s sentencing followed that of another man accused of a similar offence who was jailed in March for nine months.

Piling on the bricks

As well as closing down suppliers based in China, the government has made it more difficult for people in China to buy foreign VPN services. In July Apple dismayed civil-rights campaigners when it agreed to wipe VPN products from its Chinese app store. The company pulled down more than 600 of them. They are also disappearing from Android stores, though more slowly. Meanwhile most of the public places that used to offer unfiltered internet—such as hotels with many foreign guests—now provide the expurgated kind.

Subscribers to the best-known foreign VPN services are still able to use their accounts in China. But they were rattled in July when Bloomberg, citing anonymous sources, reported that telecoms companies had been told to block access to unauthorised “personal” VPNs, presumably including foreign ones, by February 1st 2018. China’s internet providers may well have the ability to do so: during sensitive political events foreign VPNs often become cumbersome or even impossible to use, apparently because of government-ordered efforts to throttle them. The ministry in charge of cyber affairs issued a confusing rebuttal of Bloomberg’s story. Foreign diplomats in Beijing say they are finding it difficult to get straight answers from the government about how far it intends to go.

This is worrying not just for people who want to surf the web without annoying obstructions. Many firms use their own in-house VPN systems or similar technologies to enable staff to gain secure access to corporate networks remotely. Officials say that tighter controls over VPNs will not impede such usage. But businesses worry that they may be forced instead to use government-authorised methods, including officially approved VPNs and leased lines, that are less reliable and easier to spy on than their own systems.

Those fears will only grow if a new law on encryption, presently being drafted, limits the extent to which companies are permitted to scramble sensitive communications—as some observers fear it might. Businesses have good reason to feel nervous. A cyber-security law that took effect in June allows authorities to review data, such as customer records, that firms wish to send to headquarters abroad.

As China’s increasingly autocratic leader, Xi Jinping, tightens his grip on power, it is becoming harder to remain optimistic that he will continue to tolerate circumvention of the firewall. He shows little sympathy with the complaints of foreign businesses about the difficulties they face in China. And he is clearly determined that the internet in China be made dissent-free, even if his sweeping efforts to achieve this irk members of the middle class on which the Communist Party depends for support. Last year regulators shut down many celebrity-gossip blogs and some sites that stream live events such as concerts, apparently because they could be used as platforms for embarrassing the party.

In part as a result of tightening censorship, China’s online chatter has been gradually migrating from public microblogs to instant-messaging apps such as WeChat, where users can create private groups up to 500 strong. But even in these forums, throwaway criticisms and jokes about the party get people in trouble. The government is trying to make ordinary web users act as censors themselves. In September it said it would start holding the creators of all private chat groups jointly responsible if they fail to police discussions to the authorities’ satisfaction.

The party is still haunted by the social-media-fuelled protests of the Arab spring early this decade (recent anti-government protests in Iran have been an unsettling reminder of that period: censors have ordered media not to report on them). But officials may have failed to appreciate the cost to China’s image abroad, and to the party’s at home, should it deny access to services that make online life liveable behind the great firewall. Most Chinese citizens who regularly visit forbidden websites are people who have benefited from China’s growing prosperity and who have little if any desire to challenge the party’s rule. Angering them may prove risky.