Traffic limiter/filter

We need to build an application which blocks network traffic in the
client computer of any application other than 1 we want, and also that
we can limit the amount of data transmission to a certain bandwith like
32k.

I know this might sound harsh on the user and stuff like that, but this
will be a corporate application used to control traffic of the user
when using certain other corporate applications.

So the thing is, how do we go about doing this? can this be done in
..NET? Is there some sort of commercial library that might help us do
this? We've done some initial research but found nothing really useful,
I thought maybe here someone with experience in .NET and networking
might have an idea.

Thank you so much for your help
David C.