IT Site Permissions & Portal Site Permissions open the standard Site Permissions pages for those sites. Those permission can be configured following normal SharePoint site permissioning techniques.
NITRO Site Security Settings (part of NITRO Configurations)
(The Security Settings are one of the options in NITRO Configurations. The other options are covered in another section.)
The Security Settings determine access to the NITRO Portal site. Users can be automatically directed to a certain URL, while some groups (usually admins) are not redirected.
