I don't think that we can rely on software. Maybe position the terminal where it can't be viewed privately. Maybe log all the sites visited and review this from time to time. Once the kids learn how to empty the caches and clear the logs that won't work either. Although things in today's world aren't like they used to be, parents have relied on relationships based on trust and communication with their kids for a long time and I don't think we can substitute for that yet.
Kids can probably bust any kind of technology invented.