目前防火墙发展到第 4代是基于安全操作系统的防火墙 ,文中具体探讨如何开发一个基于安全增强技术的 L inux防火墙。首先对防火墙技术的发展阶段进行了回顾和说明 ,然后就第 4代防火墙的基础——安全操作系统的设计和开发进行了探讨 ,最后给出了设计基于 L inux安全操作系统的防火墙的设计方法和实现步骤。在文章的结尾 ,对文中所设计的防火墙的今后改进方向给出了一些建议。 The current development of the fourth generation firewall is based on a secure operating system firewall, the paper specifically discusses how to develop a Linux-based firewall security enhancements. First of all, the development stage of firewall technology is reviewed and explained. Then, the design and development of the 4th generation firewall, which is the basis of the security operating system, are discussed. Finally, the design method of firewall design based on Linux operating system is given. And implementation steps. At the end of the article, some advice is given to the future improvement of the firewall designed in this paper.