Tens of millions of people are estimated to use Virtual Private Networks (VPNs) to bypass Chinese internet restrictions -- getting access to blocked websites such as Facebook and Twitter.
Beijing has for years turned a blind eye to these holes in its Great Firewall, but recent events suggest the virtual tunnels may soon be bricked up.
In January China's Ministry of Industry and Information Technology (MIIT) announced it would be banning the use of unlicensed providers of the services.
In the past few weeks, however, omens of significant tightening seem to be everywhere.
Also Read
Several luxury hotels in Beijing have said they will stop using the tools, which once provided unfiltered Internet as a convenience to their customers.
On Thursday, a cloud service provider in the capital notified users that it would practise shutting down and reporting VPN providers on the orders of Beijing's Public Security bureau.
On Sunday, Apple said it was removing a number of the programs from its app store, while Amazon's Chinese partner said that customers would no longer be allowed to use "illegal" VPNs on its cloud service.
"There have been many rounds of government murmurings about VPN crackdowns, and foreign and Chinese businesses had grown used to only minor or temporary restrictions," said Graham Webster, a senior researcher scholar at Yale Law School.
For now, however, it still remains unclear who will be able to access VPNs and under what circumstances, a situation that has left both companies and regular users on tenterhooks.
Ordinary people have reacted to the new rules with a mixture of annoyance and quiet defiance.
"You've blocked the last way to watch US TV dramas, as well as my Facebook friends!" one user of China's Twitter-like Weibo platform said after the Apple announcement.
"You can lock my cellphone, but you cannot lock my heart."
Firms are casting around for information about the developments and have expressed alarm at the potential impact on the way they do business.
Disclaimer: No Business Standard Journalist was involved in creation of this content