In this paper，we introduced 3 types of security technologies here，firewall，IDS and IPS，and discuss their advantages and drawbacks．In our case study，to overcome their drawbacks，we adapt the layered security framework to combine the 3 technologies to build a strong enough security system．For the business application，the cost effectiveness is vey import，so in our case， we show how to use free resources to build that cost effective system，and also we introduce a method on testing an IPS product，the result shows that our method is valuable and cost effective．