本文以Commer1，Commer2，Commer3本文简要介绍了目前三种主要的安全技术，防火墙，入侵检测系统以及入侵防御系统，并分析其优缺点。通过一个实例说明了如何采用分层防御技术将这3种技术结合在一起，取长补短，构建安全的防御系统。且充分考虑了成本因素，在不降低系统性能的前提下尽可能地使用免费的资源打造安全的系统，并演示了如何利用免费的工具测试入侵防御系统性能的方法，具有很大的实用价值。

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．