how to disable internet connection temporarily?

[sabin]

I live in a hostel and i have got internet connection in my room. I stay alone in my room, but my friends use my desktop relentlessly browsing internet. I need some privacy as well as some time to study!
so is there anyway to temporary block internet connection? I think you can change your IP address to do so but I have no idea how. and i dont want my friends to get suspicious of me of blocking net(wink wink)!!
Please guys help me!
short and simple steps are most welcome!!!

[marcus]

depending on your computer there is the

1) possible option of blocking internet connection (for mac) setting up a PW for your airport access when you want you can just turn it off and when someone wants to turn it on they will have to pass the required password you setup.

2) you can lock your computer set a password and require password every time your computer goes to sleep/ screen saver / every time close your laptop.

3)if you are using an ethernet cable you can physically just disconnect that, but this option is stupid

4) if you friends are stupid / inexperienced in the use of computers you can just set your network proxies settings and they wont be able to get into any websites

5) go to network / airport settings advanced change your change your IPV6 settings to off and your IPV4 settings to off , done deal.