[Radiant] Control end-user access to a page

[Luigi Rizzo]

Hello. Has been developed an extension or a solution to allow from the
admin interface to control access of end-usersto a given page/tree?
What I'd like to do is to create a "reserved" part of the site (page
which could only be accessed by a list of users which I define
(username/password) inside the radiant admin u/i. Many thanks in
advance.

Luigi