It's no secret that China has some of the strictest internet censorship laws in the world, and it's clamping down on anyone who helps circumvent the Great Firewall. A man in the southern part of the country has just been sentenced to five and a half years in jail for selling a VPN service without an appropriate license from the government.

Wu Xiangyang, from the Guangxi Zhuang autonomous region, was also fined 500,000 yuan ($76,405)---an amount equal to the profit he has made since starting the VPN four years ago, according to the newspaper of China's national prosecutor's office.

Wu allegedly sold virtual private network server access to the public via his own website, shopping site Taobao, and social media sites from 2013 until June 2017. He also sold customized routers that came read-configured to use the VPN.

In March last year, the company tweeted that 8000 foreigners and 5000 businesses used its services to access websites that are blocked by Chines authorities.

Although his sentence is more severe, Xiangyang isn't the first Chinese citizen jailed for selling unauthorized VPNs. In March, 26-year-old Deng Jiewei from the city of Dongguan in the Guangdong province was sent to prison for nine months for the same offense.

VPNs are popular among Chinese citizens looking to access services banned in the country, including Google, Facebook, and Twitter.

Back in July, China ordered the three biggest telecommunication companies to completely block access to all VPNs not registered with authorities by February 2018. The move followed the tightening of internet censorship laws that requires all audiovisual content adhere to "core socialist values." Later that same month, Apple removed a number of popular VPNs from its App Store in China.