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Recently, the explosive increase in the number of IoT devices makes the IoT becomes extremely large-scaled, and the security of such a large scale IoT emerges as a big challenge. As a classic security technique, the port scan is widely used around the world. However, as IP resources are limited, a large number of devices are located in the LAN or WLAN behind the NAT which cannot be directly accessed by the port scanner. Furthermore, port scanning generated a tremendous number of probe and response packets which may cause heavy traffic load and frequent congestion. To conquer those problems, in this article, we first propose a reverse proxy based NAT penetration system for scanning ports behind NAT. Based on the NAT penetration system, we proposed a probe delay based adaptive scanning algorithm referred to as ProDASA, which adaptively changes port scanning frequency and scanning methods to balance the network performance and security requirements of the IoT. The experiment in a real environment demonstrates the feasibility of the proposed NAT penetration system and the computational simulation with multiple virtual devices shows the advantage of our proposed ProDASA in terms of both network performance and security by comparing with a conventional method. [ABSTRACT FROM AUTHOR]

Recently, WLANs using multiple frequency bands (e.g., 5 GHz, 2.4 GHz, and 920 MHz) have become popular as a means to increase spectral efficiency. However, during multi-hop transmissions in such multi-band WLANs, the relay node experiences a significant increase in delay and loss of data frames. This happens because of the difference of link rates between the receiving and sending sides of the relay node. In order to address this problem, we consider the channel conditions of each band on either side of the relay. Accordingly, the receiving and sending rates at the relay node are measured and calculated, respectively. Based on the measured receiving rate and calculated sending rate, we propose an algorithm for the relay node to determine the optimal coding rate and modulation method so as to dynamically control the best band and channel selection for the sending side. Simulation results demonstrate the effectiveness of our proposed algorithm in terms of improvement of delay and transmission failure probability. [ABSTRACT FROM AUTHOR]

Fiber-Wireless (FiWi) network is a classification of network that combines the massive bandwidth of the optical network and the reach of the wireless network. FiWi networks are usually composed of an optical and a wireless component. Since both components are designed to work independently, some mechanisms, such as the different power saving methods in both components, may not cooperate with each other and this may result in an undesirable performance. In this paper, we identify that the conflicting power saving mechanisms cause unnecessary energy consumption and introduce additional delay to the overall FiWi network. To cope with this problem, we propose a novel ONU sleep method, which dynamically control the ONU sleep period based on the STAs energy control mechanism. Finally, we demonstrate that our proposed method has shorter latency and is more efficient in term of energy consumption than the existing method. [ABSTRACT FROM AUTHOR]