Implementation Of Personal Firewall Base On NDIS

The paper analyzes the main technology of packet filtering of Windows personal firewall kernel layer, to based on the NDIS personal firewall kernel layer fraction of analyze design and function realization carry on a discussion.Personal firewall is for solving currently various existent hidden trouble in computer network, better provide for valid guarantee of personal computer information safety and developmented as the software system, the paper discusses the research and realization of kernel layer of NDIS Intermediate personal firewall, its main thought with the Microsoft putting forward of NDIS(Network Driver Interface Specification) basic principle and NDIS layering structure for rely on, set up a NDIS Intermediate driver located on in the middle of protocol driver and miniport driver. the NDIS Intermediate driver can intercept all packets of inflow or outflow that it is catched accurately from the network subsystem of the system kernel, and according to packet filtering theory of firewall to filter the packet using filter rules , make data of not matching the filter rules intercepted at the network layer inside and not handed over upward layer or bottom layer, Combine at original in proper order match the foundation of calculate way top to put forward according to the dynamic state power value filter match calculate way combine rightness should the calculate way take into improvement, in the meantime make use of DES to encrypt or decrypt packets of be sent out and received in the proper condition, effectively guarantee the safety of user's computer.This firewall adopts and charters the technology of filtering on the basis of adopting NDIS data to intercept, design to personal users, carry on network safe protection in real time , ensure the security of the network communication of the personal computer and operating system. Apply to carry on the beneficial try with personal firewall to NDIS intermediate level package interception technology.