关键词: TCP报文 端口 标志位 防火墙 渗透

Abstract:

Firewall penetration is an important research aspect in network security, but now under the protection of firewall, much penetration software cannot g et any useful information from a host. According to the shortcomings of the existing firewall penetration tools, based on the deep research on the struc ture of TCP packets, a method through TCP packet alteration is put forward, and a penetration system based on this method is implemented. The system can detect the host directly, discover whether the host under the protection of firewall is on line. And also it can analyze the basic information such as  OS type, ports and services on the host is open or not. This information is useful for security analysis, and can also be used for the attacks as the basic information.

Key words: （TCP packet, port, flag, firewall, penetration）