Frame resolution and physical layer (PHY) protocol type detection are the basis\nof research and development of intrusion prevention systems for IEEE\n802.11 wireless network. Aiming at the problems which cannot be solved by\nthe specifications export, this paper proposed a MAC frame analytical method\nand a PHY protocol type detection algorithm based on parsing the IEEE\n802.11 packets captured by the library Libpcap. The packet structure and the\nlength of the frame preamble (18 or 26 bytes) are presented. Then the methods\nof transforming byte-order and resolving sub-fields are given. A detection\nalgorithm of PHY protocol type is proposed based on the experiments\nand examples are given to verify these methods. This work can be a reference\nfor the R & D related to link layer frame analysis.
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