MAC Frame Resolution and PHY Protocol Type Detection of IEEE 802.11

Frame resolution and physical layer (PHY) protocol type detection are the basis of research and development of intrusion prevention systems for IEEE 802.11 wireless network. Aiming at the problems which cannot be solved by the specifications export, this paper proposed a MAC frame analytical method and a PHY protocol type detection algorithm based on parsing the IEEE 802.11packets captured by the library Libpcap. The packet structure and the length of the frame preamble (18 or 26 bytes) are presented. Then the methods of transforming byte-order and resolving sub-fields are given. A detection algorithm of PHY protocol type is proposed based on the experiments and examples are given to verify these methods. This work can be a reference for the R & D related to link layer frame analysis.