Thanks people for all your tips (MIME stripping,etc).
I've figured out how you can use Websense to block real audio and it looks like it is
the easiest way to block internet radio.I blocked the following extensions
ra,rm,asx - is there some others real audio format extensions that I should block?
P.S.For those who use Websense and wonder how this can be done I attached file with
explanation how to configure it to block real audio.
The Websense server is a URL filtering server. It takes requests for URLs
compares them to our database to determine a category, then determines if
the requesting party has been granted access to that category, and if so it
allows the URL request to be processed, if not it returns a page to the user
that tells them that the site is blocked and under what category.
Real Audio is a file format.
To block this format you must block the ability to request that file type by
a HTTP request.
To do this you will want to add the file extensions to the keyword blocking
category
This can be done by opening the websense manager, and selecting the keywords
options on the left of the screen (the white window frame).
1) Then create a new category in the user defined category by
right clicking on it and selecting "add a custom category", and name it
keywords.
2) Then select that category and type this in the right pane
where it is labeled "Enter URL keywords for this category"
\.ra
(make sure you included the backslash) then click
Add Keywords on the bottom right.
3) Then add another
\.rm
(make sure you included the backslash) then click
Add Keywords on the bottom right.
4) Next go to the Category list that is implemented in the
policy that you want to block access to Real Audio
5) Select "Edit Category Set"
6) Then scroll down to the "User Defined" section and click the
plus sign to the left of it to expand the category.
7) Select the "Keywords" category that you just added
8) Click on the checkbox on the that is labeled "Block
Keywords"
9) Then click "Save ALL" on the upper left corner to apply the
changes
Now any HTTP request that is made for Real Audio formats will be denied.
This can be replicated for any file extension that you would like to block.
