Structural Design of Several Protocols in Stateful-Inspection Firewall
状态检测防火墙中几种协议的结构设计*

Introduces the development and characteristic of the firewall, analyses the working principle of the stateful-inspection firewall. The data structure of the state table and rule table is built. Considering the security and performance of the firewall ,presents the structural design for TCP, UDP, ICMP, ARP, which is the main protocol in the TCP/IP stack. Method of TCP sequence number check, UDP virtual conuection,ICMP package inspection easure the security and high performance of the network.