haha, tim ra roi, day chinh la cai minh can
If you had such a site with lots of Flash files, how would you protect against hotlinking? lighttpd’s solution, applicable to any file type, is mod_secdownload. You write a function (examples in the link include PHP and Ruby) to generate a special URL, and the module cracks the URL to permit access to a given file for a given amount of time.
ps: dang dung ubuntu nen ko co tieng Viet, keke