Researchers warn of alarming rise in China’s regional internet censorship

Cybersecurity analysts are warning of growing regional censorship in China, where provincial authorities sometimes block “ten times more websites” than the country’s infamous “Great Firewall”.

A new study presented at the IEEE Symposium on Security and Privacy assessed reports from the province of Henan since August 2023 and found it had deployed its own regional censorship system.

The IEEE is an American association for electronic and electrical engineers.

Researchers, including from Stanford University, say Henan is using censorship systems based on computer networking protocols that inspect and block web traffic leaving the province.

This local system is simpler than the country’s overall firewall but is “volatile and aggressive” when blocking specific sites, they say.

“While the Henan firewall is less sophisticated and less robust against typical network variability, its volatile and aggressive blocking of second-level domains made it block ten times more websites than the Great Firewall at some points in time,” the study says. “Our work documents an alarming sign of regional censorship emerging in China.”

China has long had one of the world’s most sophisticated internet filtering systems, with citizens having to increasingly rely on virtual private networks to access American services like Google, Facebook and Instagram.

The country has also banned many VPN services, further curtailing access to the Western digital world.

The latest study points to a worrying trend of local censorship of ever more international content beyond what’s blocked at the national level.

Researchers said they found millions of domains that were allowed by China’s centralised firewall but, at different points of time, remained inaccessible in Henan.

In the study, security experts accessed servers from internet cloud providers to test the flow of web traffic from various parts of Henan.

Their analysis included the web traffic flow in Hunan to and from the internet’s top one million domains between November 2023 and March 2025.

They found that Henan’s local firewall blocked some 4 million domains at some point in that period, more than five times the 741,500 domains blocked by the Great Firewall.

Many of the blocked websites were related to business in contrast to “more of the news and media as well as adult content domains” targeted by the Great Firewall.

This practice of blocking business-related websites at the regional level could be tied to several finance-related protests in the province in recent times, according to the study.

“We hypothesise that the province of Henan has been a centre of a lot of financial controversies, with the most prominent being the mass protests in 2022 that were a result of a financial scandal involving local lenders,” researchers wrote. “Given the financial scandals targeting state-controlled financial institutions, it’s very probable that the state wants to limit access to information that is relevant to the economy of the area.”

Alternatively, researchers argued, this could be an attempt to censor critics of the country’s business and economic policies.

“This localised censorship suggests a departure from China’s centralised censorship apparatus, enabling local authorities to exert a greater degree of control within their respective regions,” researchers said. “We hope our study sounds the alarm to the broader censorship research community to be aware of and further study emerging regional censorship in China.”