I increase httpd.conf:
Now I would like only one subdomain: h.domain.com to load hobbies.php
Which lines should i add into my .htaccess file to achieve this?
This will work, however i can't test drive it right now. Try it out.
SetEnvIfNoCase Referer "^http://h.domain.com" allow_hobbies=1 <FilesMatch "hobbies.php"> Order Deny, Allow Allow from env=allow_hobbies </FilesMatch>
Note: You need to most likely not depend about this for security reasons, as you will find ways around it (relatively easy ones at this). The Referer header could be photoshopped.