I’m assuming you want a free “Active Directory” basically for authentication. You can use TekRADIUS, freeware http://www.tekradius.com/. As per changing the bandwidth, are you referring to bandwidth to the application package? If that is the case, you would need to refer how the application works via a regular browser or a fat client on the user’s computer. On the Server hosting the TekRADIUS, you can install use Traffic Shaper http://bandwidthcontroller.com/trafficShaperXp.html.