“Restrict Registration” is a plugin for WordPress that allows you to control 
who is registering on your blog. This plugin uses simple blacklists and 
whitelists to define who can register for your blog, and who is restricted. Use 
simple literal matching, flexible asterisk wildcard matching, or powerful 
regular expression matching: it’s your choice! The options page is clear and 
easy to use. Set your lists, and you’re done!
This plugin was inspired by WP-Deadbolt, but has been completely rewritten and 
redesigned, and several new features have been added.

Restrict Registration

Use simple blacklists and whitelists to control who can and cannot register on your blog.

Alex Mills

Have a private blog that you only want your friends or family to read? Then this plugin may be for you. It will redirect all users who aren’t logged in to the login form where they are shown a user-friendly message.
This plugin also features a configuration page where you can easily toggle allowing guests to access your feeds.
A very simple plugin that does only does a simple thing.

Registered Users Only

Works on 4.6. Simple install and use. It's perfect!



Perfect!

Forces all users to login before being able to view your site. Features an options page for configuration.

Restrict Registration vs Registered Users Only