Unmanaged server adjustments
 

I have an unmanaged server which allow to be created links like:

http://www.whatever-keywords.sitename.com/ (this show main page from sitename.com)
How to fix this as i see lot of pages like
http://www.whatever-words.sitename.com/ indexed in google, but those pages are only duplicate content of main page.

Is there a way to redirect those pages to main page or to show a 404 error message or a Server not found page?