Software to enable / disable Internet access?

Question

Computer networks

Hello!
There is a computer class (25 PCs). It is necessary to organize the ability to enable or disable Internet access on these computers from the teacher's PC. Tell me, what software exists for this? Ideally, I would like to be able to disable or enable access separately for each PC or all at once.

Answer 1

proxy, firewall, router
You need not software, but a solution. It is not clear how you now have access to the Internet organized.

Answer 2

You need to install a proxy server on your computer, such as HandyCash or SmallProxy. True, it seems that HandyCash is only free for five users. Then, in the browser settings (network settings section) of the students' computers, specify the IP address and port of the computer with the proxy server. Everyone will go to the Internet through this computer. But this simplest scheme is easily bypassed by simply changing browser settings.
It can be done a little more difficult. Physically launch the Internet through the teacher's computer. Install an additional network card and a proxy server. Plug the wire into the additional network card through which the Internet comes, and on the card that is already there, put a fixed IP address from the same subnet that is currently in use. On other computers, in the properties of the network connection, specify the IP address that was assigned on the teacher's computer as the gateway. Unfortunately, I don’t remember exactly whether it is necessary to share the Internet connection on the teacher’s computer. It seems that with a proxy server installed, this is not necessary.