Intrusion Detection :
 

In the last few years, the science of intrusion detection has moved from the black magic realm to a viable solution that should be deployed in every network that is considered business critical. In fact, intrusion detection systems have improved from recording log files, to expert-like analysis reports, to actually performing some proactive blockage that eliminates the perceived threat automatically. Again, like any other security subject, choose your tool wisely and place them everywhere that you consider has business critical assets that you do not want compromised.

 
For more product specific details, see
 
Intrusion Detection » IIS
  Intusion.com