This paper introduces a applied firewall model. According to the model,it designs a applied firewall system that includes package filter,applied proxy,Authentication and Applied encrypt.

• 文章引进一个实用的防火墙模型，在此模型的基础上，设计了一个包括包过滤、应用代理、身份验证和应用级加密相结合的实用防火墙系统。