Bester, you can also use DNS-services which have family filters.
Many router software are total crap, but there might be a way to install yout own OS on them. I have open-wrt running on mine and I can balcklist sites for the entire network from there, but also set the DNS servers for the entire network or for individual machines. This is nice in the battle against adds and scams sites, but could also work for parental control. If you don't hand out the router root user to other people, there is no way anyone can change to settings. (especially if you block physical access to the router as it might have debugging ports/pins or hard reset buttons). If a new machine (a new computer is bought, a friends laptop comes to the LAN) appears, it will also fall under these rules.
A combination of these might work the best.
There is, still, the problem that you could for example VPN-tunnel around these. Of course, this requires some technical know-how and if I had a kid that could do that I would be happy and try to support them in learning more about comptuers...
But most router firewalls also allow you to block ports and services. Many also have the possibilty to cast several networks (like a guest network and your own). So you could have different settings for the kids and your self (in case you need to VPN).
Also, you can set another DNS server for an individual computer. Many people do this when the use public wifi to avoid redirects. But this can be blocked by nor giving root to kids on their computer (just like no android users have root, you don't need it). Also, if the hosts has bad sites black listed, changing the DNS server on the machine would not get past this anyway. You can download ready made black lists with the worst known offenders.
You cannot prevent them from, say, borrowing a friends mobile and using that. However, it makes it a bit more harder and potentially embarrassing to ask to loan someone else's phone...
Hallvor wrote:I wouldn't bother. Kids will always find some way around them - in your house, in their friends' houses or with their mobile phones.
Uhmmm.. mobile phones are actually the easiest to control. Google and Apple offer services that allow you to monitor every single thing your child does. You can, of course, also see your own google search history and all the youtube videos that you have looked at and so on with a tool in the settings of the account. Not everyone realizes this, I guess. Additionally, they have extra features for kids, so that parents can see where they are on the map with gps, decide what apps they can install, what sites they can visit and how many hours per day various things on the phone can be used. It's also become normal (at least where I live). So for example, you are expected to follow them on gps if you are a responsible parent, so that they don't get lost or something else.
Personally I think nudity should not be feared. We are mammals and we do mammal things and children should learn that. In a way there is and should not be anything special about the fact that there is nudity and the people are sexually attracted by it. Sex should be a normal and good thing like getting hugs and food (and all other things we need because of our evolutionary history). Empirical evidence shows that people with a healthy sex life even are physically more healthy.
But then on the other hand, there is some sick porn stuff on the net that could cause quite bad experience or trauma even for children. Also, porn addiction and these kinds of things are probably real.