This paper makes a comparison firstly on the merits and the shortcomings of some typical packet filtering models, such as NIT, CSPF (CMU/Stanford Packet Filter) and BPF (Berkeley Packet Filter) etc.

• 本文首先比较了具有代表性的包过滤机制如CSPF(CMU/Stanford Packet Filter)和BPF(Berkeley Packet Filter)等的优缺点，详细分析了BPF模型；