I am searching for it on Google, but i didn't find anything. Is there a way tho set up proftpd that it will only accept a connection on ftp.website.ext and not on website.ext or test.website.ext
I am running proftpd on Debian 5
I think the last part of this article may help? It discusses listening only on specific IP addresses.
From other repsonses you've made, it seems you want it to be hostname based, and the IP addresses for these hosts are all the same. The answer is, no, you cannot do that, sorry. FTP is an old, old protocol and does not handle hostnames. The client doesn't have any mechanism to send the requested hostname along, and the server has no facility to accept it.
Use a combination of VirtualHost and Default Address blocks much in the same way you'd do Apache:
Untested by me but looks like it should work.