With the extensive application of Zigbee, some bodies of literature were devoted into finding the vulnerabilities of Zigbee by fuzzing. According to earlier test records, the majority of defects were exposed due to a series of testing cases. However, the context of malformed inputs is not taken account into the previous algorithms. In this paper, we propose a refined structure-based fuzzing algorithm for Zigbee based on FSM, FSM-fuzzing. Any malformed input in FSM-Fuzzing is injected to the tested sensor against a specific initial state. If the sensor transferred to the next state of FMS or crashed, there would be a defect of Zigbee in dealing with the input under the state. The final state of the sensor is verified by an UIO sequence. After a round of tests, the sensor is regressed to the specific state to prepars for receiving the next mutation. All of the states would be traversed in FSM-fuzzing. A fuzzing tool, ZFSM-fuzzer, is designed for evaluating the performance of FSM-fuzzing. Experiment results show that there is a vulnerability of Zigbee in dealing with the frames without destination addresses. Further, the quality of cases of FSM-fuzzing is higher than the previous algorithms. Therefore, FSM-fuzzing is powerful in finding the vulnerabilities of Zigbee.
In the field of wireless industrial automation net works (WIANs), the WirelessHART and ISAI00.11a proto cols are promoted, which support time division and carrier sensing multiple access schemes, channel hopping schemes, and mesh network topology to improve reliability and scalability. However, they work on the 2.4-GHz non-licensed industrial, scientific, and medical (ISM) frequency band. This band has become crowded in industrial applications, i.e., ZigBee, Blue tooth and wireless local area networks (WLAN), which has led to coexistence issues. Here, we investigated experimentally the data link layer packet loss rate olWirelessHART and ISAI00.11a protocols coexisting with IEEE S02.15.4 and IEEE S02.11n-based WLAN interference systems. The experimental testbed comprised WirelessHART, ISAI00.11a, ZigBee, and IEEE S02.11n-based WLAN systems. During the test, either the WirelessHART or the ISAI00.11a served as the system under test and the other systems were used for wireless interferences. WirelessHART and ISAI00.11a field devices were developed to set up WirelessHART and ISAI00.11a networks systems. All the systems were distributed in a wide and real industrial environment with metal structures and industrial equipment generating interference. Finally, a series of experiments was performed. The experimental results and analysis provide useful information on coexistence issues for system designers and standard developers of WIANs.
This paper presents an analysis of the signal and noise in deep-submicrometer ultranarrow-track disk recording by composite simulation models, including the micromagnetics in longitudinal media and giant magnetoresistive (GMR) multilayers and the surface finite-element methods for inductive thin film heads and GMR head shields. The analysis assumes that the linear density of the recording process is in a range of 57 to 1200 kilo-flux changes per inch (kfci) and the width/gap ratio of the write head is between 4 and 2, corresponding to current industry practice. The first to fifth harmonics of all-one signals are found by the simulated spectrum. The signal and noise at different track densities and linear densities are analyzed by the harmonics in the spectrum. The composite heads in the disk recording system with widths 160, 240, and 320 nm are evaluated by the signal-to-noise ratio at a linear density around 1000 kfci.Index Terms-Deep-submicrometer track width, longitudinal recording, magnetic heads, micromagnetic, signal-to-noise ratio.
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