Wireless Local Area Networks present several vulnerabilities that are exploited, and as a result, numerous attacks have been developed and used against them. Although countermeasures to detect and eliminate such threats have been created throughout the years, few methods exist to prevent the attacks. IEEE 802.11 covert channels could be considered a candidate to prevent Wi-Fi attacks since they allow secret communication between the client station and the access point without establishing an association. They can be implemented in frames that attackers do not target. This paper presents a new covert channel that prevents Wi-Fi attacks. We also describe metrics, and discuss the performance results of the proposed solution. We show that the new protocol is able to achieve high efficiency of operation.

Evaluation offruits and leaves ofseventeen apple cultivars in respect of their attraction as food for caterpillars of leafroller species occurring in an experimental apple orchard was carried out over 1995 to 1998 in the Institute of Pomology and Floriculture at Skierniewice. The highest levels ofinjuries were observed on two cultivars: ‘Ligol’ and ‘Elstar’. High number ofinjured fruits was noted on the following cultivars: ‘Gala’, ‘Jonagold’, ‘Cortland’, ‘Idared’, ‘Lodel’ and ‘Szampion’. By far the number of injured fruits was lower on ‘Lobo’ and ‘Jonathan’, and the least on ‘Rubinette’, ‘Starkrimson’ and ‘Gloster’. Significant differences in the number of caterpillars settled down in leaf/flower clusters ofparticular cultivars during the vernal period were also confirmed. In each season the highest number ofcaterpillars of Pandemis heparana and Archips rosana were observed on leaves of‘Alwa’. To cultivars whose leaves were also readily settled down by the two aforementioned species were: ‘Jonathan’, ‘Cortland’, ‘Ligol’, ‘Lobo’, ‘Jonagold’ and ‘Elstar’. Relatively less caterpillars were observed on leaves of‘Arlet’, ‘Gloster’, ‘Szampion’, ‘Starkrimson’, ‘Pilot’, ‘Pinowa’ and ‘Rubinette’.