Video QoS/QoE over IEEE802.11n/ac: A Contemporary Survey

The demand for video applications over wireless networks has tremendously increased, and IEEE 802.11 standards have provided higher support for video transmission. However, providing Quality of Service (QoS) and Quality of Experience (QoE) for video over WLAN is still a challenge due to the error sensitivity of compressed video and dynamic channels. This thesis presents a contemporary survey study on video QoS/QoE over WLAN issues and solutions. The objective of the study is to provide an overview of the issues by conducting a background study on the video codecs and their features and characteristics, followed by studying QoS and QoE support in IEEE 802.11 standards. Since IEEE 802.11n is the current standard that is mostly deployed worldwide and IEEE 802.11ac is the upcoming standard, this survey study aims to investigate the most recent video QoS/QoE solutions based on these two standards. The solutions are divided into two broad categories, academic solutions, and vendor solutions. Academic solutions are mostly based on three main layers, namely Application, Media Access Control (MAC) and Physical (PHY) which are further divided into two major categories, single-layer solutions, and cross-layer solutions. Single-layer solutions are those which focus on a single layer to enhance the video transmission performance over WLAN. Cross-layer solutions involve two or more layers to provide a single QoS solution for video over WLAN. This thesis has also presented and technically analyzed QoS solutions by three popular vendors. This thesis concludes that single-layer solutions are not directly related to video QoS/QoE, and cross-layer solutions are performing better than single-layer solutions, but they are much more complicated and not easy to be implemented. Most vendors rely on their network infrastructure to provide QoS for multimedia applications. They have their techniques and mechanisms, but the concept of providing QoS/QoE for video is almost the same because they are using the same standards and rely on Wi-Fi Multimedia (WMM) to provide QoS

Efficient authentication mechanism for defending against reflection-based attacks on domain name system

Domain Name System (DNS) is one of few services on the Internet which is allowed through every security barrier. It mostly depends on the User Datagram Protocol (UDP) as the transport protocol, which is a connectionless protocol with no built-in authentication mechanism. On top of that, DNS responses are substantially larger than their corresponding requests. These two key features made DNS a fabulous attacking tool for cybercriminals to reflect and amplify a huge volume of requests to consume their victim's resources. Recent incidents revealed how harsh DNS could be when it is abused with great complexity by attackers. Moreover, these events had proven that any defense mechanism with single point deployment couldn’t accurately and efficiently overcome an attack volume with high dynamicity. In this paper, we proposed the Efficient Distributed-based Defense Scheme (EDDS) to overcome the shortcomings of a centralized-based defense mechanism. By using an authentication message exchange, which is a Challenge-Handshake Authentication Protocol (CHAP)-based authentication mechanism. It is deployed on multiple nodes to determine the legitimacy of the DNS request. Moreover, it significantly reduces the impact of the amplification factor for the fake DNS requests without having any side effects on legitimate ones. Then, a Stateful Packet Inspection (SPI)-based packet filtering is proposed to distinguish legitimate requests from fake ones by considering the results of the authentication procedure. Both authentication-message exchange and SPI-based filtering are introduced to provide detection accuracy without reducing the quality of service for legitimate users. As the simulation results show, the proposed mechanism can efficiently and accurately detect, isolate, and discard the bogus traffic with minimal overhead on the system