随着网络安全问题日益严重，网络安全产品更加受到人们的重视。防火墙作为最早使用和使用量最大的安全产品，受到了用户和研发机构的青睐。作为防火墙的最基本的核心技术一网络数据包过滤技术，直接关系到防火墙的性能和稳定性。 本文基于NDIS中间层驱动，实现了对网络数据包的过滤。由于 NDIS 中间层工作在核心层、能够截获到完整的最原始的数据帧，相比其他数据包过滤方法有显著的优越性。并且在以太网的实验环境中，可以根据任意的数据包头的信息过滤网络数据包。

Along with the problem of network safety increasingly and seriously, the product of network safety is much more attached importance to by people. Fire wall as the product of satety which is the first and the most used is subjected to the favor of the customer and developer. Packet filtering as the most basic kerneled technique of fire wall relates to the function and the stability of the fire wall directly. This text is based on the NDIS intermediate driver and carries out the function of packet filter. NDIS works in the kerneled layer and can intercept and capture the whole and the most original data frame and comparing with the other method contains obvious advantage. At the same time according to the information of the discretional packet header it can filer packet in the experiment environment of Ether net.