Florin Andrei wrote:
This is the kind of issue best solved by a notice from management saying "thou shall not listen to internet radios at the office, or else". Then just monitor the network for violators.
Purely technical solutions are not very good. You can block certain user agents in a proxy or via a Network IPS, block certain MIME types or file types (again, either a proxy or an NIPS can do that), drop HTTP sessions that are longer than say 5 minutes (at the firewall or NIPS, and yes, drop sessions even if they are active - bad idea sometimes but it will greatly annoy the streaming radio users) and add a temporary denial for that source/destination IP pair, do traffic shaping to limit the bandwidth available to streaming content (at the firewall or router), etc. In general, a smart NIPS can help you somewhat. But nothing is perfect and people are likely to be smarter than a piece of hardware.
One more idea: if most of them listen to the same radio station, just install a streaming proxy (or relay) on the internal network and then you can have a lot of internal users connected to the same proxy (relay), all of them using essentially just one stream to the outside. E.g., look at option -r with streamripper:
http://streamripper.sourceforge.net/tutorialconsole.php
Heck, even if two or three stations are the most popular, stream them all to an internal relay and tell everyone to use the relay. It's better to have just two or three streams, instead of twenty, the users are happy, everyone wins.
I think the points mentioned by some people here are useful. I think it is a mgmt thing and not a technical thing. If users want to listen to radio, you know, can listen to real radio. Unless there is a technical problem caused by internet radio, I think the radio thing is not a technical issue.