An approach for mass level filtering is described below with India as an example:
How internet enters India?
Where to place this filter?
Ideally at the Cable Landing Stations. This is gateway and filtering here protects all citizens.
How the filter works?
Copy of affidavit filed in PIL on December 16, 2014 is here (PDF).
What is ready to use?
Brain scanner is ready and polished. Database of 2,00,000 sites is ready and growing.
DNS filter integrated with scanner is ready.
High-capacity firewalls are available from various OEMs.
Work under development?
Filters for popular Proxy/VPN tools are under development.
Scanner can detect porn content in images/videos. This is under refinement to tackle selfie and low resolution pictures.