just set permissions in the site map - leave the root site (or
subsite) with "read" granted to "The Public", and set all your
mounted packages with "read" only granted to "Registered
Users"... you'll need to set the mounted packages to not inherit
permissions from their parent though... when someone not
logged in tries to go to a page within a mounted application
they'll be redirected to a registration/login page...
don't set the root site to only allow registered users have access
though, otherwise people will need to be logged in in order to
reach the login page... :(
