Kick the hackers away

I'm going to assume that you're talking about Wordpress sites. I don't think you really need any plugins to keep your sites secure. All you have to do is:

1. Keep you plugins, themes, Wordpress installation up to date.
2. Only use plugins you really need and only stick to the popular ones if possible. This is because less popular plugins won't be used as much and therefore some security vulnerabilities might not have been patched.
3. Delete plugins and themes you don't use since hackers can still exploit vulnerabilities of themes and plugins that are disabled.
4. Restrict the wp-admin folder to your IP addresses unless you allow user registration. You can do this by adding this code to your site root's .htaccess file:
AuthUserFile /dev/null
AuthGroupFile /dev/null
AuthName “Access Control”
AuthType Basic
order deny,allow
deny from all
# whitelist home IP address
allow from xx.xx.xx.xx
5. Don't use the admin account that would have been the default when you installed Wordpress.
6. Use a different table prefix than wp.
7. Make sure that your directory doesn't get listed whenever an index file is not present.

@ Jessen: Thanks for the very useful and helpful tips.

Hello,

.htaccess allows you to control access to your pages, directories, subdirectories, etc.

start from here : search wikipedia for .htaccess
Please note though, that this is just the beginning and won’t keep away real experts.

Security is a set of tools and best practices and ongoing check/correct process.

regards,

There's a great plugin called Security Scan that helps to change the directory file names and give you an idea of the security level of your site.

WordPress › WP Security Scan « WordPress Plugins

Use the Plugins called "WP Security Scan" Its Good enough .

Hello,

the WP plugin corrects only known and predefined issues, which by the way can be changed without any plugins. The problem is that we constantly modify our sites, content, configurations, install new plugins, etc. Thats what creates vulnerabilities! So, yes, WP security is nice, but thats just about it.

regards,

use wordpress security scan, run the scan and you can see what further steps you need to take to make your wordpress site a bit more secure.

I recently had some security problems with my WordPress sites, and ended up doing a lot of research into securing WordPress sites...

I have now written up my experiences in a comprehensive Security Checklist which can be downloaded for free from The WordPress Security Checklist.

My checklist has quite a few items and detailed steps for how to get the job done.

That might help you on the way...