I'm looking for a way to block internet connectivity to a MAC on my network after it's been active for a set amount of time.

For example:

My son gets home from school and gets on his computer, everything he does is online so the router starts seeing traffic to his computer.  At this point I want to start a time for, say, two hours.  After the two hours of use I want internet access shut off.  I'd really like to be able to pause this if the router notices a break in activity for something more than 5 or 10 minutes, and then resume.  Is anyone good enough with 'nix to help me accomplish this?  I'm currently running Shibby and can install optware if there is something there that could make it easier.

Thanks!

Instead of relying on some lenghty and ultimately by-passable tech fix, have you considered parenting?

No! You are a true genius!

What Kos said. Far too much hassle to setup when what you actually need is communication. Though I'm definitely not telling you how to parent because I don't have kids so know fuck all.

I think Ken is trying to 'parent'. It seem he has suggested 2 hours a day is enough net access and wants the kids to stick to that - would anyone here be able to do that if it wasn't fixed?

Thanks Jon.

I can't hover over them all day, I'm too busy and I've caught them on the computers after we've all gone to bed as well.  I do have an access restriction rule set up that turns their internet off at certain times in the evenings during the week and at a different time on the weekends, but that's not what I'm trying to do with this request.

If I say to them you can use the internet for 2 1/2 hours an evening and then to the garage to do some work or whatever it is I'm currently doing I can't be keeping track.

But what should they be doing otherwise?

Anything.  My son will spend every waking moment on his computer if I let him.  I just put up his basketball hoop, go outside, get some fucking sun son!  Do your homework!  Help me with projects!

Do you ask him to do these things? Sounds like he definitely needs a hobby of some sort. 

If it helps, I basically the same. The only real exception was cadets which was a huge exception, admittedly.

Anyway, end result is computers pay the bills and I can't afford all of my offline hobbies!

I am too. I'm not the driving force behind this but I am the one who gets to hear about it non fucking stop.