Whenever I try to access SSRS 2008 R2 through a URL (i.e. after being published on the net), it always shows a login prompt when accessing the report. The problem does not appea
I'd start with using Internet Explorer, on a domain.. which will pass your credentials (if that is how you have this configured).
It IS possible to configure firefox to pass Windows Authentication / Token.. I don't remember how I had done this previously.
The BEST platform for using SSRS is Apple / Safari.. because when you hit the checkbox that says 'remember password' it actually remembers the password. It blows my mind that Chrome, Firefox, IE give you a prompt that says 'remember password' - but from my experience, remembering passwords only work as I expect when I am using Safari.