a) Fail2Ban: Which will ban IP address after few failure attempts
website : http://www.fail2ban.org/wiki/index.php/Main_Page
b)Rootkit Hunter : It will scan your server for any unauthorized scripts.
Website :http://www.chkrootkit.org/
To download : http://sourceforge.net/projects/rkhunter/
c)PortSentry : This tool will block IP who is trying to scan your server for open ports.
Ref : http://www.securityfocus.com/infocus/1580
http://www.securityfocus.com/infocus/1586
How to install : http://www.falkotimme.com/howtos/chkrootkit_portsentry/
d)mod_security
http://www.modsecurity.org/
e) mod_evasive : It will ban IP for certain conditions ,example :
- Requesting the same page more than a few times per second
- Making more than 50 concurrent requests on the same child per second
- Making any requests while temporarily blacklisted (on a blocking list)
Web Site : http://www.zdziarski.com/projects/mod_evasive/
To be.. continue..