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.

sander85

This plugin allows to block spammers with the following options:
<ul>
<li>Block spammers by IPs (supports wildcards).</li>
<li>Block IPs that have posted comments marked as spam.</li>
<li>Block comments that contain bad words.</li>
</ul>
Additional options:
<ul>
<li>If comment contains bad words, add the spammers IP into the blacklist.</li>
<li>When deleting spam, add IPs of spam comments into the blacklist.</li>
<li>Similar entries in the blacklist are merged automatically.</li>
</ul>

Block Spammers

Block spammers from submitting comments, by IPs or by bad words.

Real IP Detector vs Block Spammers