Ask Slashdot: Parental Content Control For Free OSs?

m.alessandrini writes Children grow up, and inevitably they will start using internet and social networks, both for educational and recreational purposes. And it won't take long to them to learn to be autonomous, especially with all the smartphones and tablets around and your limited time. Unlike the years of my youth, when internet started to enter our lives gradually, now I'm afraid of the amount of inappropriate contents a child can be exposed to unprepared: porn, scammers, cyberbullies or worse, are just a click away.

For Windows many solutions claim to exist, usually in form of massive antivirus suites. What about GNU/Linux? Or Android? Several solutions rely on setting up a proxy with a whitelist of sites, or similar, but I'm afraid this approach can make internet unusable, or otherwise be easy to bypass. Have you any experiences or suggestions? Do you think software solutions are only a part of the solution, provided children can learn hacking tricks better than us, and if so, what other 'human' techniques are most effective?