BuddyPress.org

@life1134
You could try this and take what you need from it:
http://wpmu.org/how-to-build-a-facebook-style-members-only-wordpress-buddypress-site/

@life1134
You could use:
https://wordpress.org/plugins/private-community-for-bp-lite/
and in the plugins settings use wp-login.php as the redirect.