Images remixed by Oiwan Lam.

China's notorious Great Firewall makes it difficult — but not impossible — for Chinese netizens to access sites like Twitter, Facebook, western news outlets like the New York Times, and thousands of other websites, not to mention Global Voices.

For years, netizens in China (and other countries with heavy restrictions on Internet content) have used virtual private networks (VPNs) that allow them to circumvent censorship by creating a secure and well-hidden connection to another network in a different geographic location.

But their days using VPNs may be numbered.

Netizens are anticipating that the majority of VPN apps serving individuals’ needs will be taken down from Apple and Android App markets by 1 July 2017.

Whisperings of a state ban on unauthorized VPNs spread widely on Twitter and Weibo after the popular VPN service provider Green announced that the company would cease operations by 1 July. Below is the company’s letter to its customers, dated 22 June:

尊敬的Green用户
接上级监管部门通知，我们必须很遗憾地告诉大家：Green将于2017年7月1日起停止服务。由此给各位造成的不便，我们深表歉意！
服务停止后，我们将开始处理需要退款的用户申请（金额根据剩余的服务天数计算）。如需退款，请务必于2017年8月31日前提交退款信息，超过该时间将无法受理。由于登记、核对、转账的工作量较大，退款到账时间暂无法承诺。预计于8月31日统计核对工作完毕后，Green将开始处理退款，敬请您能耐心地等待退款到账。
是您的每一次点赞与肯定，鼓励我们一直坚持到了今天，我们始终心存感激。此后，Green团队将进行转型，期待有缘与您再次相会。

Dear respected Green customers,
We have received notice from the higher authorities. We regret to inform you that Green will cease our service on July 1st, 2017. We apologize for any inconvenience caused.

We will start processing our users’ refund request after service stopped (the amount will be calculated based on the remaining days in your plan). If you need a refund, please make sure to submit your refund request by August 31, 2017. We won’t be able to process any refund request submitted after that date. Since the workload of processing the requests, information verification and money transfer would be huge, we won’t be able to set an exact date for the refund. We plan to process the refund soon after August 31, please wait patiently.

Your praise and affirmation have encouraged us to last as long as we have. We will always be grateful for this. In the future, the Green team will transform the business. We look forward to meeting you again.

Green is just one of the VPNs that appears to be facing a mandatory shutdown. VPN providers including Netfits, VPN Master Pro, Ponhon, Snap VPN, SkyX, among others have disappeared from Apple and Android app stores over the past few months.

While some companies offering these services are banned or disrupted in China, others are fully licensed to operate. It has been estimated that 1-3% of China's internet users use circumvention tool to visit overseas websites.

People who follow the news closely might have anticipated the coming of a full VPN ban. In January 2017, China’s Ministry of Industry and Information Technology announced that it would ban “illegal services” that carry out cross-border operations, including unauthorized virtual private networks (VPNs), until March 2018.

Yet July 2017 is eight months ahead of March 2018, and state authorities have made no official announcement of the ban being expedited.

Chinese human rights activist Hu Jia believes that the ban is related to the upcoming 20th anniversary of Hong Kong being handed from British to Chinese power, which falls on July 1. A few months later, the 19th National Congress of the Communist Party of China will meet in November. He said on Twitter:

#七一 香港自由法治20周年沦陷日和下半年中共 #十九大，会是两个筑墙锋锁网络的高潮。#习近平 本人主抓网络安全，投入力度和效率远较过去加大了。#习特勒 https://t.co/dsFMVeWuVI

— Hu Jia 胡佳 (@hu_jia) June 23, 2017

#July 1 the 20th anniversary of the doomsday of Hong Kong's rule of law and freedom and the CCP #19 Congress around end of the year would be the heyday of the Great Fire Wall. #Xi Jinping is responsible for cybersecurity and he is more heavy-handed and effective in controlling the net. #Xitler.

Chinese President Xi Jinping will be visiting Hong Kong for the July 1 ceremony and the city will be under high security control in this week. As for the 19th National CCP Congress, a majority of the Politburo Standing Committee (top decision-making body) is expected to retire and new members will be replaced. It is a critical moment for the party, which has been experiencing internal political struggle in recent years.

Some Chinese Twitter users are worried that they won't be able to climb over the wall again soon:

随着封杀升级，很多翻墙软件被停，翻墙随时都会成为历史，珍惜能翻墙上推特的每一天。如果有一天，我不能翻墙了，你们会想我吗？

— 秀才江湖 (@xiucai1911) June 22, 2017

As censorship measures escalate, many circumvention tools have been forced to stop. Climbing over the wall may become history. We have to treasure the days when we can still access Twitter. If one day I cannot climb over the wall, will you miss me?

Others believe that the move is related to Chinese billionaire Guo Wengui’s corruption allegations against top Chinese official Wang Qishan, the secretary of Chinese Communist Party's anti-corruption agency. Guo Wengui himself believes this too. In a reply to Mr. Sun's comment about the VPN ban, he said:

孙先生好：封禁VPN是又一次的美国之音的断播事件．这是上天赐给我们的又一个大礼物……他们有多猖狂．多恐惧．我们就会有多强大！他们的任何愚蠢行动都会让我们大陆的同胞会从沉默中醒来！墙一定会被推翻的！我们的国际上的朋友从来没有像今天一样愿意与我们共同一起战斗！一切都是刚刚开始！ https://t.co/tt1nYkHH8Y

— 郭文贵Guo Wengui ✊️✊️✊️ (@KwokMiles) June 23, 2017

Dear Mr. Sun: The ban on VPNs is another incident similar to the ban on Voice of America. It is another gift from the heaven… The more furious and mad they become, the stronger we become. All the stupid acts that they have done will only help our fellows in mainland China to wake up. The wall will fall. Friends from the international society are now more willing to fight with us. Everything has just begun.

In a June 16 interview with Mingjing magazine, Guo showed the US passport and social security number of the wife of Wang Qishan, indicating Wang's wife has long been a US citizen. The exposé rebuffs the party's claim that it is cracking down on “naked officials”, cadres of prominent party members whose wives or children live overseas.

Guo also showed the addresses of multiple luxury houses owned by alleged relatives of Wang. Since the allegations were so explosive, many from mainland China have climbed over the Great Firewall to watch Guo’s video streaming on YouTube.

Netizens believe that some domestic VPN providers will still be operating after July 1, but there is no guarantee that communication via authorized networks will be safe from surveillance. For now, netizens on Weibo, Twitter and WeChat are anxiously sharing tips and strategies for climbing over the wall.