Spammer Blocker free wordpres plugin

Source:http://wordpress.org/extend/plugins/spammer-blocker/

If you are tired of blocking spammers's IP addresses manually, you can use this plugin. It blocks all visitors who posted a comment that was later marked as a spam. For example if your Akismet catches a silly bot who posted a spam comment, it will be blocked until you delete it's IP address from your database.

Features
Two ways to detect spammers
Configurable banned message
Advanced tools for managing IP addresses
Simple backup tool