redirect if call not from main page

on a page:
1.have header
2.have iframe name = 'iframe'

header has stuff like: <a href = '../jsp/some.jsp' target = 'iframe' ...

A:Now, it is also posible to open ../jsp/some.jsp direct via mydomain/jsp/some.jsp' , but there is then no header, which is what I dont want.

Is there a way to detect A event and abort jsp processing at start and then redirect to main page ?

I think the solution to this is somewhere within .htaccess

But, I'm not an .htaccess expert.
Maybe someone else might see this thread and offer some insight.