Protect WordPress blogs with free Wordfence plugin

Optionally repair changed files that are security threats.
Scans for signatures of over 44,000 known malware variants that are known security threats.
Scans for many known backdoors including C99, R57, RootShell, Crystal Shell, Matamu, Cybershell, W4cking, Sniper, Predator, Jackal, Phantasma, GFS, Dive, Dx and many many more.
Continuously scans for malware and phishing URL's including all URL's on the Google Safe Browsing List in all your comments, posts and files that are security threats.
Scans for heuristics of backdoors, trojans, suspicious code and other security issues.
Checks the strength of all user and admin passwords to enhance login security.
Monitor your DNS security for unauthorized DNS changes.
Rate limit or block security threats like aggressive crawlers, scrapers and bots doing security scans for vulnerabilities in your site.
Choose whether you want to block or throttle users and robots who break your security rules.
Includes login security to lock out brute force hacks and to stop WordPress from revealing info that will compromise security.
See all your traffic in real-time, including robots, humans, 404 errors, logins and logouts and who is consuming most of your content. Enhances your situational awareness of which security threats your site is facing.
A real-time view of all traffic including automated bots that often constitute security threats that Javascript analytics packages never show you.
Real-time traffic includes reverse DNS and city-level geolocation. Know which geographic area security threats originate from.
Monitors disk space which is related to security because many DDoS attacks attempt to consume all disk space to create denial of service.
Wordfence Security for multi-site also scans all posts and comments across all blogs from one admin panel.
WordPress Multi-Site (or WordPress MU in the older parlance) compatible.
Premium users can also block countries and schedule scans for specific times and a higher frequency.
Our online forums are available 24/7 to answer your WordPress security questions."