Masoud Binaei

This plugin allow WordPress to detect Real visitors IP Address when WordPress is behind of Reverse Proxy, Load Balancer or CDN. 
It will start working as soon as you activate it.
It is also compatible:
<ul>
<li>Cloudflare.com</li>
<li>geniusguard.com</li>
<li>central-hosting.com</li>
<li>incapsula.com</li>
<li>sucuri.net</li>
<li>barracuda.com</li>
<li>f5.com And Other…</li>
</ul>

Real IP Detector

Very good

This plugin allow WordPress to detect Real visitors IP Address.

Pippin Williamson

Easily put your site into maintenance mode with this plugin so that you can perform updates. The plugin works by taking a selection of IP addresses and comparing them to the visitor’s IP address.
Users whose IP addresses match those specified in the settings page can view the site normally. Users who do not have IP access are directed either you a WordPress page (which you pick), or to any external url.
It’s extremely simple to use:
<ul>
<li>activate the plugin</li>
<li>go to the “Maintenance Mode” settings</li>
<li>check the “Enable Box”</li>
<li>enter the IP addresses that should have access</li>
<li>choose whether to redirect non-authorized users to a page or url</li>
<li>choose the page or enter the url</li>
</ul>
Once your site is ready to be made available again, simple uncheck the “Enable” box.

CGC Maintenance Mode

Good options, no check if the URL is on the same domain which causes redirect loop.



Almost there

This plugin allows you to put your site into maintenance mode, by allowing only users with specified IP addresses to view the site.

Real IP Detector vs CGC Maintenance Mode