Control internet connexion
I am trying to develop an application (C++/Qt preferably for Multi-platform) that allows to control and filter the data stream entering and leaving the network (mainly internet), and to restrict the access of certain URL to be reached in the browser,
Is that possible with Qt?? If not are there libraries that can do this??
Or is there any APIs that I can use to help control the connection on the computer?
You can use a firewall to filter the traffic leaving your computer. To filter the traffic of the complete network you need to run your software on the router connecting your network to the internet. All the other computers will not see the traffic not directed at/originating from them (under normal circumstances), so they can not manipulate it.
Firewall setup is heavily OS dependent, there is no support in Qt for that. You might want to investigate router distributions like "openwrt":https://openwrt.org/ or "ipfire":http://www.ipfire.org/ or countless others. They can be configured to do what you describe without the need to do programming:-)
Qt can be used in such kind of development, but it doesn't provide such functionality....
If you are developing for linux, you can do this with simple kernel module. Search for "kernel sockets" etc... I'm not sure, but it is also possible on Windows with hooks, but I don't remember how can it be done exactly...
Anyway, it is not Qt related...
Ok and about restrincting access to certain URL to be reached in the browser?? There is a way to block a list of web sites??
What do you want to do? Your nick suggests that you are up to no good:-)
Short answer: You can if you control the browser, the computer or the network. But usually a knowledgeable user will be able to step around your blocker with less work than it is for you to set it up.
PS: Users tend to become knowledgeable soon after they notice that something is blocked.
So there is no stable soft solution for it. So how antivirus do then?? (like kaspersky has a parental control in it) There is a link that explain how they do??
My guess is that they run a local proxy and use the local firewall to force traffic to go through that proxy.
In my experience those products mostly provide a cozy feeling for the parents. Google usually has some easy to follow instructions to get around the restrictions, and if there is nothing there some kid in school will be able to help out.