Design And Realization Of Personal Firewall Working On Windows2000 Platform

Information security is increasingly becoming issues that whether of corporation and individual pay attention to.Firewall as network security product of the earliest appearance and the most uses is the favour of user and research institution.Personal firewall is effective measure that ensure desktop system security.It can scout packets that are passed between computer and network.It can also decide packets to pass or interdict by predefine standard.Firewall solves worries when personal users who require higher security level connect to Internet.Windows 2000 is the best OS(operating system) for Internet business and learning network programme, which is based on Windows NT technology. Its compatibility is the best in NT family.But windows2000's leak is many and many attacks aim at it. When PC is using Windows 2000 OS to connect with Internet,it is worthwhile to take the problem of how to protect its security into account.After simply reciting correlative knowledge of network security and firewall,this paper introduces needed theory of developing this firewall.Then the whole structure and function is expatiated.As a whole the system may compart three modules:main program , monitoring application programs who access network, filtering network packets. Main program is a application program working on user mode.lt is a user interface and provides dialogs between user and firewall. The module of monitoring application programs who access network is dynamic link library in user mode.Dll working on application level can capture network packets in application level and may obtain detailed information of process that access Winsock2 SPI. The module of filtering network packets is NDIS intermediate driver in kernel mode.NDIS intermediate driver can intercept all bottom data packages and don't need to take care of packages in user mode.Thereby we overcome the shortcoming during .caputuring packet by kernel mode or user mode only greatly improve the system security nature. At present,the core technology of developing personal firewall is the intercepting technology of network data packages,so this paper mainly research realization of two intercepting modules of NDIS driver and SPI.At last this paper introduces installation and test of the two modules.The test achieves my aims.In addition the paper tests the application programs and the result is their actions are right.