I agree with Chris. Technological barriers won't work. We can't stop SPAM and viruses, things which most of us try very hard to stop. When there are people in the house actively trying to subvert the filters the task becomes becomes well neigh impossible.

You want a form of filter that does work: try putting the computer in the living room or family room, with the screen facing outwards so everybody can see it. That will work far more reliably, drives home the point about family values, and is free.

It won't stop the kids from seeing stuff you don't want them to, however. If they can't do it at your house, they will do it somewhere else. It isn't like there is a shortage of computers out there for them to use - starting with their or their friends phone. Most phones double as Internet browsers now. Teaching them to handle and respond to such stuff responsibly is a whole other problem.

Welcome to the digital sea, parents.