> Else what prevents things like usage of Google analytics/fonts etc from triggering a match and blocking?
The blocking was/is complementary. Usually, domain names themselves were blocked by DNS poisoning (or IP blocking if it escalated), domains themselves (or the names of the websites) did not appear in the keyword blocklist. A link to Google Analytics or Facebook button could stuck the webpage from loading properly until a timeout, but merely mentioning or linking a domain name would not trigger a keyword match of the page itself.
The intention of keyword matching was to allow partial access while still blocking unwanted content. Usually, only the most politically unwanted keyword entered the keyword list. For example, Wikipedia could be accessed normally, but as soon as "a word that should not be named" appeared in the webpage, the connection would be reset immediately. An interesting phenomenon was, sometimes the page could partially load and stopped exactly before the forbidden word. And since the censorship system worded on mirrored traffic, sometimes a slight processing delay allowed the full page to load before the RST was received, it would be a "I'm feeling lucky moment".
Anyway, there was how the system worked before 2010. The extensive use of HTTPS rendered it useless, and it appeared that some forms of keyword filtering has already been lifted, since it's already a pointless exercise.
For quite some time after keyword matching became ineffectively, DNS poisoning remained the only form of censorship for many unwanted but not significant websites, for example, Hacker News. But recently, SNI matching was implemented.
The blocking was/is complementary. Usually, domain names themselves were blocked by DNS poisoning (or IP blocking if it escalated), domains themselves (or the names of the websites) did not appear in the keyword blocklist. A link to Google Analytics or Facebook button could stuck the webpage from loading properly until a timeout, but merely mentioning or linking a domain name would not trigger a keyword match of the page itself.
The intention of keyword matching was to allow partial access while still blocking unwanted content. Usually, only the most politically unwanted keyword entered the keyword list. For example, Wikipedia could be accessed normally, but as soon as "a word that should not be named" appeared in the webpage, the connection would be reset immediately. An interesting phenomenon was, sometimes the page could partially load and stopped exactly before the forbidden word. And since the censorship system worded on mirrored traffic, sometimes a slight processing delay allowed the full page to load before the RST was received, it would be a "I'm feeling lucky moment".
Anyway, there was how the system worked before 2010. The extensive use of HTTPS rendered it useless, and it appeared that some forms of keyword filtering has already been lifted, since it's already a pointless exercise.
For quite some time after keyword matching became ineffectively, DNS poisoning remained the only form of censorship for many unwanted but not significant websites, for example, Hacker News. But recently, SNI matching was implemented.