以前对防火墙接触甚少，所了解的也是从系统底层实现角度看的一些分析细节，最近由于毕业设计的需要，对防火墙的发展、分类、现状和趋向等方面做了概略的了解，也有一些体会，做个简单的分析报告。 -previously little contact with the firewall, as well as knowledge of the underlying system from the point of view of achieving the details of some analysts, the recent graduate design needs, the development of firewall, classification, and the status and trends so on a broad understanding, have some experience and become a simple analysis.