marcucci

This is a very simple plugin that will check to see if a visitor is logged in before allowed your WordPress site to be displayed. 
If they are not it will display the login page of your site. It will also add text on the login page to explain that the site 
required all visitors to login.

Password Protect Plugin for WordPress

Force all visitors to login before accessing your wordpress site and add a message on the login screen explaining that login is required.

Abolfazl Sabagh

rng-refresh Plugin adds the meta box in edit post screen of the admin panel also you can add time period with template <code>Hour:Minutes:Seconds</code> of force refresh using it.
Main features in rng-ajaxlike include:
<ul>
<li>Very light and easy to use.</li>
<li>This plugin avoids from any conflict with other plugins.</li>
<li>has not any overhead.</li>
<li>Has a settings in order to determine post types that can have refresh meta box.</li>
</ul>
it is strongly was recommended that after the plugin is activated, go to the <code>Settings > Refresh Settings</code> and configure plugin.

rng-refresh

WordPress Plugin that refreshes the single template of public post types with a synchronism time period.

Password Protect Plugin for WordPress vs rng-refresh