防火墙工作原理与技术之研究

防火强的工作原理简单的说就是对通信包的接受或者拒绝。大多数防火墙采用的技术和标准均有所不同。这些防火墙的形式多种多样：有的取代系统上已经装备的TCP／IP协议栈，有的在已有的协议栈上建立自己的软件模块，还有一些应用型的防火墙只对特定类型的网络连接提供保护（比如SMTP或者HTTP协议等），以上的产品都可以叫做防火墙，因为他们的工作原理都是一样的：分析出入防火墙的数据包，决定接受还是丢弃。

Firewall Work Principle and Technology Research

Fire Strong works simply means that the communication packets to accept or reject.Most firewalls use of technology and standards are different,the firewall in many forms：some systems have been equipped to replace the TCP/IP protocol stack,and some of the existing protocol stack to build their own software modules,Some application-based firewall only for certain types of network connections to provide protection（such as SMTP or HTTP protocol,etc.）,the above products can be called a firewall,beeause their works are the same：analysis of the data packets out of the firewall,decide whether to accept or discard.