Network anomaly detection is an important and dynamic research area. Many network intrusion detection methods and systems (NIDS) have been proposed in the literature. In this paper, we provide a structured and comprehensive overview of various facets of network anomaly detection so that a researcher can become quickly familiar with every aspect of network anomaly detection. We present attacks normally encountered by network intrusion detection systems. We categorize existing network anomaly detection methods and systems based on the underlying computational techniques used. Within this framework, we briefly describe and compare a large number of network anomaly detection methods and systems. In addition, we also discuss tools that can be used by network defenders and datasets that researchers in network anomaly detection can use. We also highlight research directions in network anomaly detection.

Network Anomaly Detection: Methods, Systems and Tools

Due to the broadcast nature of radio propagation, the wireless air interface is open and accessible to both authorized and illegitimate users. This completely differs from a wired network, where communicating devices are physically connected through cables and a node without direct association is unable to access the network for illicit activities. The open communications environment makes wireless transmissions more vulnerable than wired communications to malicious attacks, including both the passive eavesdropping for data interception and the active jamming for disrupting legitimate transmissions. Therefore, this paper is motivated to examine the security vulnerabilities and threats imposed by the inherent open nature of wireless communications and to devise efficient defense mechanisms for improving the wireless network security. We first summarize the security requirements of wireless networks, including their authenticity, confidentiality, integrity, and availability issues. Next, a comprehensive overview of security attacks encountered in wireless networks is presented in view of the network protocol architecture, where the potential security threats are discussed at each protocol layer. We also provide a survey of the existing security protocols and algorithms that are adopted in the existing wireless network standards, such as the Bluetooth, Wi-Fi, WiMAX, and the long-term evolution (LTE) systems. Then, we discuss the state of the art in physical-layer security, which is an emerging technique of securing the open communications environment against eavesdropping attacks at the physical layer. Several physical-layer security techniques are reviewed and compared, including information-theoretic security, artificial-noise-aided security, security-oriented beamforming, diversity-assisted security, and physical-layer key generation approaches. Since a jammer emitting radio signals can readily interfere with the legitimate wireless users, we also introduce the family of various jamming attacks and their countermeasures, including the constant jammer, intermittent jammer, reactive jammer, adaptive jammer, and intelligent jammer. Additionally, we discuss the integration of physical-layer security into existing authentication and cryptography mechanisms for further securing wireless networks. Finally, some technical challenges which remain unresolved at the time of writing are summarized and the future trends in wireless security are discussed.

/pdf/a-survey-on-wireless-security-technical-challenges-recent-3uamoalvot.pdf

A Survey on Wireless Security: Technical Challenges, Recent Advances, and Future Trends

The use of unmanned aerial vehicles (UAVs) is growing rapidly across many civil application domains, including real-time monitoring, providing wireless coverage, remote sensing, search and rescue, delivery of goods, security and surveillance, precision agriculture, and civil infrastructure inspection. Smart UAVs are the next big revolution in the UAV technology promising to provide new opportunities in different applications, especially in civil infrastructure in terms of reduced risks and lower cost. Civil infrastructure is expected to dominate more than $45 Billion market value of UAV usage. In this paper, we present UAV civil applications and their challenges. We also discuss the current research trends and provide future insights for potential UAV uses. Furthermore, we present the key challenges for UAV civil applications, including charging challenges, collision avoidance and swarming challenges, and networking and security-related challenges. Based on our review of the recent literature, we discuss open research challenges and draw high-level insights on how these challenges might be approached.

Unmanned Aerial Vehicles: A Survey on Civil Applications and Key Research Challenges

This paper examines the security vulnerabilities and threats imposed by the inherent open nature of wireless communications and to devise efficient defense mechanisms for improving the wireless network security. We first summarize the security requirements of wireless networks, including their authenticity, confidentiality, integrity and availability issues. Next, a comprehensive overview of security attacks encountered in wireless networks is presented in view of the network protocol architecture, where the potential security threats are discussed at each protocol layer. We also provide a survey of the existing security protocols and algorithms that are adopted in the existing wireless network standards, such as the Bluetooth, Wi-Fi, WiMAX, and the long-term evolution (LTE) systems. Then, we discuss the state-of-the-art in physical-layer security, which is an emerging technique of securing the open communications environment against eavesdropping attacks at the physical layer. We also introduce the family of various jamming attacks and their counter-measures, including the constant jammer, intermittent jammer, reactive jammer, adaptive jammer and intelligent jammer. Additionally, we discuss the integration of physical-layer security into existing authentication and cryptography mechanisms for further securing wireless networks. Finally, some technical challenges which remain unresolved at the time of writing are summarized and the future trends in wireless security are discussed.

/pdf/a-survey-on-wireless-security-technical-challenges-recent-k705wofne7.pdf

A Survey on Wireless Security: Technical Challenges, Recent Advances and Future Trends

Smart grid is a promising power delivery infrastructure integrated with communication and information technologies. Its bi-directional communication and electricity flow enable both utilities and customers to monitor, predict, and manage energy usage. It also advances energy and environmental sustainability through the integration of vast distributed energy resources. Deploying such a green electric system has enormous and far-reaching economic and social benefits. Nevertheless, increased interconnection and integration also introduce cyber-vulnerabilities into the grid. Failure to address these problems will hinder the modernization of the existing power system. In order to build a reliable smart grid, an overview of relevant cyber security and privacy issues is presented. Based on current literatures, several potential research fields are discussed at the end of this paper.

https://repository.um.edu.mo/bitstream/10692/2883/3/Liu-2012-Cyber-security-and-privacy-issues-i.pdf

Cyber Security and Privacy Issues in Smart Grids

Targeted as the main protocol of delay/disruption-tolerant networking (DTN) for space, bundle protocol (BP) is intended to establish an overlay network for reliable file delivery in a heterogeneous networking environment. Reliable data transmission mechanisms of BP are presently under development. In this paper, a new transmission approach is proposed for BP for highly reliable data delivery in deep-space vehicle communications in presence of an unpredictable or random link disruption. The main idea of the proposed approach is to use a hybrid of proactive retransmission and reactive retransmission mechanisms during file transfer. Analytical models are built in various transmission cases to study the effect of link disruption on reliable transmission of BP, with focus on the number of failed transmission attempts, file delivery time and goodput performance normalized with respect to the total amount of data sent. The models are validated by the file transfer experiment over a PC-based testbed. A performance comparison between the proposed approach and the existing transmission approach with respect to transmission reliability is also presented.

Hybrid Retransmissions of Bundle Protocol for Reliable Deep-Space Vehicle Communications in Presence of Link Disruption

As the main data transport protocol of delay/disruption-tolerant networking, Licklider transmission protocol (LTP) is developed to provide reliable and highly efficient data delivery over unreliable deep-space and interplanetary communication channels. For reliable data delivery, a checkpoint (CP) segment of LTP is sent, with a timer set (or, simply, CP timer) to check the arrival status of the entire data block at the receiver, and it is retransmitted upon the expiration of the CP timer prior to reception of an acknowledgment. Little work has been seen in analysis of the CP timer length for optimal performance of LTP in energy-efficient, reliable data delivery. In this article, a packet-level analysis of the CP timer length setting is presented for the reliable data delivery of LTP over unreliable deep-space communication channels based on realistic file transfer experiments conducted using a PC-based testbed. It is our intent to find an optimal CP timer setting so that the reliable file delivery in deep space is ensured with a minimum number of retransmission attempts. By this, the energy-efficient, reliable data delivery of LTP can be achieved in deep-space communications.

Study on Checkpoint Timer Optimal Setup of Licklider Transmission Protocol

There is an urgent need for finding an optimal transmission mechanism in the space-based Internet. This paper presents an experimental analysis of the throughput performance and transmission behavior for the rate-based and window-based congestion control mechanisms in a simulated small-satellite environment using a PC-based test-bed. The experimental analysis revealed that the traffic shaping mechanism of a rate-based transmission is more effective than the bursting flow of a window-based mechanism in error-prone space environment with a long link delay. The window-based transmission mechanisms show performance degradation due to traffic bursts and frequent packet retransmissions caused by their ACK-clocked congestion control. Pure rate-control is preferable to other mechanisms in space when bandwidth reservation is available.

An experimental analysis of rate-based and window-based transmission mechanisms over simulated space-Internet links

Delay-/disruption-tolerant networking (DTN) is developed for reliable data delivery in challenging communication environments characterized by a very long propagation delay and/or lengthy, random link disruption and highly lossy data links. Space-based networks and deep-space communication scenarios are typical of this type of communication environment. Bundle protocol (BP) and Licklider transmission protocol (LTP) were developed as the main protocols of DTN for reliable data transmission in space. Some studies have been done in evaluating the transmission performance, mainly throughput/goodput, on the use of BP/LTP for reliable file delivery in deep-space communication scenarios. The National Aeronautics and Space Administration (NASA) has also demonstrated DTN and implemented the use of its BP protocol on the International Space Station (ISS) for data delivery to the earth ground station. However, a little work has been done in analyzing the performance of BP/LTP for reliable data/file delivery from the ISS to the ground stations, especially in presence of link disruption. In this paper, analytical modeling and the numerical evaluation results are presented to study the effect of link disruptions on the use of BP/LTP for reliable file delivery over a relay-based communication architecture between the ISS and the ground stations.

Effect of Link Disruption on BP/LTP over a Relay-based Communication Architecture for International Space Station

The default acknowledgment (ACK) strategy of TCP easily overruns the constrained ACK channel capacity of the asymmetric network links. There is no effective ACK mechanism to address the asymmetric channel problem for space-Internet. A configurable ACK delay (CAD) mechanism has been developed to delay the ACKs for a configurable period of time to improve the TCP throughput performance over asymmetric space-Internet links. This paper introduces the CAD mechanism and presents a performance evaluation of it in an experimental manner. The experimental results show that the CAD mechanism has significant performance advantages in asymmetric space links with a channel ratio higher than 50/1. The higher the asymmetric channel ratio is, the more advantageous the CAD is over the default ACK strategy.

Ruhai Wang

Papers

Hybrid Retransmissions of Bundle Protocol for Reliable Deep-Space Vehicle Communications in Presence of Link Disruption

Study on Checkpoint Timer Optimal Setup of Licklider Transmission Protocol

An experimental analysis of rate-based and window-based transmission mechanisms over simulated space-Internet links

Effect of Link Disruption on BP/LTP over a Relay-based Communication Architecture for International Space Station

WLCp2-10: Configurable Acknowledgment Delay (CAD) Mechanism for Asymmetric Space-Internet Links