David Sader

Adds three more levels of privacy(visibility) to the Settings–>Reading page.
<ol>
<li>
Site visible to any logged in community member – “Network Users Only”.
</li>
<li>
Site visible only to registered users of blog – “Site Members Only”.
</li>
<li>
Site visible only to administrators – “Site Admins Only”.
</li>
</ol>
<a href="https://codex.wordpress.org/Create_A_Network" rel="nofollow ugc">Multisite</a> Network Admin can set an override on site privacy at “Network Visibility Selector” on Network Settings page
Multisite Network Admin can set privacy options at Network-Sites-Edit under “Settings Tab” as well.
Network Admin receives an email when blog privacy changes.
RSS feeds require authentication.
robots.txt updates accordingly.
Ping sites filters correctly.
Privacy status reflected in Dashboard “Right Now” box.
Uses WP3+ functions auth_redirect(), network_home_url(), and home_url() for SSL login redirects.
Login message has link to sign-up page of a “Network Users Only” blog or a link the blog admin email if user is logged in but not a member of a “Members Only” blog.
Localization ready.

More Privacy Options

Hi. 
Thanks for the great plugin. 
It works out-of-the-box in WP 4.9.8

Kudos!!!

Simple and elegant

Adds three more levels of privacy(visibility) to the Settings-->Reading page.

Daniel Bachhuber

Digital First Media

Site Secrets is a simple plugin to keep your WordPress site private. When active, it will redirect all unauthenticated users to the login screen.
By default, Site Secrets requires that the user has been added to the site. You can broaden the permissions model to any logged-in users with the following snippet added to your theme’s <code>functions.php</code> file or a mu-plugin:
<pre><code>add_filter( 'site_secrets_requires_membership', '__return_false' );
</code></pre>
We’re happy to receive feedback, questions, feature suggestions, and <a href="https://github.com/DFMdata/Site-Secrets" rel="nofollow ugc">pull requests</a>

More Privacy Options vs Site Secrets