restricting web access

my boss assigned me a task the software should be in vb6.0
this is the scenario
1) a database is running in the server
2) in the client there should be a small exe should be running,the exe asks for the user name and password which is validated against the data in the server
3)if validation success then he will be able to surf the internet else restrict the internet access.
4)the users on the client system shall be allowed to use ms office and other applications except to go online.

any guidelines will be greatly appreciated.
:sick:

An easy way that comes to mind, which most basic computer users wouldn't be able to figure out, is just have your program change proxy settings for whatever browser is installed (IE, FireFox, etc.). Changing it to something invalid will prevent internet browsing. But that could be a poor choice.

Another, you can modify the Windows HOSTS file (Google it). This might work.

Those are the most simple solutions that come to mind. There are more advanced options like DLL injection to block socket connections, but that would require a little C++ and I don't think it is allowed here.

yes sir, i choose the poor choice, i changed the proxy. but i am probing for approaches like tweaks in windows hmm.... any ideas

The problem with changing proxy settings is that even if the user doesn't figure it out, it only disables web browsers. Programs that can access the internet still would be able to do so. There was a thread like this a couple weeks ago that had a reasonable solution. Lemme see if I can find it again. :)

I couldn't find the other thread. This one showed promise for the disconnect. It doesn't say how to reconnect again, but hopefully it steers you in the right direction.