The Research And Realization Of PC Firewall Based On Network Packet Filter

Today there are lots of dangers in the system of computer network, and traditional firewall can't protect every PC in local area network. So the research of PC firewall has its special value.This article mostly concerns design and implement of a PC firewall with the core technology of network packet filter. The implement of the PC firewall base on the knowledge: windows network system, the framework of windows system, OSI 7 layers protocol, the implement of TCP/IP in windows and network packet filter in windows network platform.The article expatiates on the mechanisms and realization of the network packet filter on windows platform, and compares with all kinds of these technologies. So Winsock 2 SPI is chosen to build up this PC firewall. And then SPI programming is introduced with more detailed, including the function, installing order, and installing process of transport provider.The article illuminates the function and flow of every part of the program, designs detailed log and simple interface. Using blocking idea, the PC firewall accomplishs the network packet filter, and take some means to withstand the Trojan Horse program.Many tests prove that the PC firewall fulfils the requirement. The article analyzes the results and proposes some outlook of this implementation.