At first China also used Cisco's stuff, but soon they could't keep up with the requirements of the Chinese govt. After that a man usually criticized to be "the father of GFW", FANG Binxing, came up and built more powerful censorship hardware and software for the govt at Beihang U. It is said that they now use supercomputers to parse, analyse and block (and even inject, remember GitHub?) all packages going through the Chinese network boundary.

Oh I just gave away so much secret. I'm so doomed. Everything above are just made up stories. Don't believe me. Don't track me down. Please.