Is the Contents Group in ISA the solution? If yes, what type of files should I block?
Typically, Real Audio uses ports like 7070 to connect. The user can, however, configure the player to connect using HTTP only mode. So you could attempt to block all extension types associated with streaming music: WMS, WMZ, AIF, AIFF, SND, AVI, WMA, MP3, ASF, etc. You could also configure the server to block traffic by mime type. Check out http://www.isaserver.org it's a good site to obtain more information on specific ISA questions.
This was first published in December 2002