I've got a hosting account where I've my primary site (world wide web.mainsite.com indicates root folder), along with a subfolder xpto.com, where I wish to have another site (world wide web.xpto.com).

I'm able to access world wide web.anothersite.com by typing world wide web.mainsite.com/xpto.com. Also, using cPanel, I have rerouted world wide web.xpto.com to world wide web.mainsite.com/xpto.com.

My real question is: it is possible to method to prevent world wide web.xpto.com access by typing world wide web.mainsite.com/xpto.com, so it may be utilized only by typing world wide web.xpto.com?

EDIT: also, I'd rather not world wide web.xpto.com to become utilized via world wide web.xpto.mainsite.com. Any help?

Hope I've described this clearly :)