China’s Internet censors have been busy over the Christmas weekend, with reports suggesting the country has blocked access to Google’s Gmail service since December 26.

Web traffic research outfit Dyn Research said that Gmail’s traffic is being blocked at the IP source, which means the service is inaccessible to most Chinese netizens. The disruption is still believed to be ongoing at the time of writing.

The sudden drop in traffic can be seen at Google’s Transparency Report, which displays an interactive graph showing how the number of Chinese visitors to Gmail fell off a cliff. The graph fluctuates for a while, before a long period of flat-lining.

“China has a number of ways they can block content,” said Earl Zmijewski, Vice President of Dyn Research, to Mashable. “One of the crudest ways is to just block an IP address, and when you do that, you block all the content available at the IP”.

Dyn Research later confirmed its theory of an IP level block on Gmail via a tweet:

@DynResearch confirms China #GFW IP-level block of Google’s http://t.co/XhsNku2A6Q when served from #HongKong pic.twitter.com/uV3Y8pgHTQ

— Dyn Research (@DynResearch) December 28, 2014

It’s significant that Hong Kong is mentioned, because much of China’s Gmail traffic is routed via IP addresses from the territory. The assault on Gmail was also noted by Chinese Twitter users:

China blocks Imap 4 Gmail. Netizens report they can no longer get Gmail on Apple Mail (OSX) & Mail (iPhone) or domestic Internet providers. — Yaxue Cao (@YaxueCao) December 28, 2014

China is notorious for blocking foreign websites and services at random intervals, forcing news agencies and other sites into a game of cat and mouse as they try to evade the “Great Firewall of China”. The only way for Chinese citizens to access Gmail at this point would be to use a virtual private network (VPN), which routes a user’s Internet connection through servers located in other countries, or else the Tor Project web browser.

Google hasn’t yet commented on the reports, nor indicated if it will take any action to get Gmail back online in China.

photo credit: harmonica pete via photopin cc