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Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Satellite networks are recognized as the most essential communication infrastructures in the world today, which complement land networks and provide valuable services for their users. Extensive coverage and service stability of these networks have increased their popularity. Since eavesdropping and active intrusion in satellite communications are much easier than in terrestrial networks, securing satellite communications is vital. So far, several protocols have been proposed for authentication and key exchange of satellite communications, but none of them fully meet the security requirements. In this paper, we examine one of these protocols and identify its security vulnerabilities. Moreover, we propose a robust and secure authentication and session key agreement protocol using the elliptic curve cryptography (ECC).We show that the proposed protocol meets common security requirements and is resistant to known security attacks. Moreover, we prove that the proposed scheme satisfies the security features using the Automated Validation of Internet Security Protocols and Applications (AVISPA) formal verification tool and On-the fly Model-Checker (OFMC) and ATtack SEarcher (ATSE) model checkers. We have also proved the security of the session key exchange of our protocol using the Real or Random (RoR) model. Finally, the comparison of our scheme with similar methods shows its superiority. [ABSTRACT FROM AUTHOR]

Software-defined networks have many benefits such as more control over the control plane and reduced operating costs through separating the control plane from the data plane in network equipment. One of the most critical problems in software-defined networks is a controller placement problem, which significantly influences its overall performance. The purpose of this problem is to determine the number of controllers required and how to assign switches. This paper attempts to solve this problem, aiming to reduce the network's operational cost and to improve their survivability and load balancing. Hence, we have tried to divide the network into several subdomains using segmentation. Then, we used multi-criteria decision-making methods to solve the controller placement in each subdomain. For this purpose, we considered criteria such as reliability rate, cost, delay, and processing capacity. To assign switches to controllers, we used the proposed mathematical model to minimize the objective function while observing the defined constraints. Furthermore, according to the proposed architecture, we used distance to the central controller, adjacent neighborhood, and controller memory to select the cluster head controller for each subdomain to communicate with the central controller. Finally, we performed experiments on topologies Uran, SwitchL3, and Sinet of the Internet Topology Zoo to evaluate the proposed method. In these experiments, we compared the results of the proposed method with our work-related methods, including Controller Placement Analytic Hierarchy Process (CPAHP) and Controller Placement Modified Density Peak (CPMDP), in terms of criteria such as cost, survivability, number of controllers, connection failure probability, average delay, and controller load-balancing rate. The results show that the proposed method outperforms CPMDP and CPAHP. Thus, the proposed method has a 24.97% and 19.76% improvement in reducing network implementation costs than CPMDP and CPAHP, respectively. [ABSTRACT FROM AUTHOR]

Software‐defined networks are a modern architecture in computer networks where traffic transfer is separated from network control. In software‐defined networks, all decisions are made in the controller, and the necessary commands are injected into the network equipment. With the advent of software‐defined networks and the introduction of a new concept called controller in these types of networks, it becomes important to find an appropriate location for the controller and its number in the network. This problem aims to find the location and the optimal number of controllers needed in the network, and how to assign switches to the controllers declined certain constraints. In this article, a method to determine the appropriate location for controllers is proposed, so that the cost of network implementation would be reduced and thus its survivability is improved. Finally, we analyzed the proposed method in terms of evaluation criteria. [ABSTRACT FROM AUTHOR]

In the Internet of Things networks deploying fixed infrastructure is not always the best and most economical solution. Advances in efficiency and durability of Unmanned Aerial Vehicles (UAV) made flying small cell base stations (BS) a promising approach by providing coverage and capacity in environments where using fixed infrastructure is not economically justified. A key challenge in covering an area with UAV-based small cell BSs is optimal positioning the UAVs to maximize the coverage and minimize the number of required UAVs. In this paper, we propose an optimization problem that helps to determine the number and position of the UAVs. Moreover, to have efficient results in a reasonable time, we propose complementary heuristic methods that effectively reduce the search space. The simulation results show that our proposed method performs better than genetic algorithms. [ABSTRACT FROM AUTHOR]

Information system security is one of the most important challenges of today's organisations. Although most organisations use security technologies, they have come to the conclusion that technology alone is not enough. In this study, we analysed and ranked the opinions of IT experts, managers, and Ph.D. students concerning the role of knowledge management in creating, recording, sharing, and applying information security knowledge. First, we identified 62 knowledge management techniques and tools. Then, 20 techniques and tools were investigated in knowledge management cycle using fuzzy screening through interviews and questionnaires. Finally, the network analysis methods, DEMATEL, and VIKOR were employed for weighting, internal relationships, and ranking each of the tools in the evaluation cycle. According to the results, " Knowledge Base" was the most important factor in creating and recording knowledge. In sharing and diffusing knowledge, " Categorisation of Knowledge "scored the top, while "Knowledge Maps" were the most important tool in knowledge application. [ABSTRACT FROM AUTHOR]

The Internet of Vehicle sensors generate huge data that are processed by cloud servers, but this leads to high latency and bandwidth occupies. This was the main motivation behind fog computing. Software-defined network (SDN) was developed to simplify the traditional networks’ architecture. Sometimes, when a fog server fails to execute some tasks, it sends them to cloud servers while other fog servers are idle. This leads to inefficient utilization of fog computing resources. This letter aims to optimize the resource utilization of fog computing with meeting the deadlines of tasks via assigning them to an optimal fog server using SDN. Moreover, local and global load balance techniques are proposed. The simulation results revealed that our proposed system decreases the transference of tasks to the cloud and as a result decreases the latency and bandwidth consumption. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In mobile ad hoc networks, route selection is one of the most important issues that is studied in these networks as a field of research. Many articles trying to provide solutions to choose the best path in which the important parameters such as power consumption, bandwidth and mobility are used. In this article, in order to improve the solutions presented in recent papers parameters such as power remaining, mobility, degree node and available bandwidth are used by taking the factors for each parameter in proportion to its influence in choosing the best path. Finally, we compare the proposed solution with the three protocols IAOMDV-F, AODVFART and FLM-AODV with the help of OPNET simulation program based on network throughput, routing discovery time, the average number of hops per route, network delay. [ABSTRACT FROM AUTHOR]

Session initiation protocol (SIP) is an application layer signalling protocol for the set-up, management and termination of multimedia networks such as voice over IP standardised by Internet Engineering Task Force. This protocol has also been recognised by International Telecommunication Union as a main core of next-generation networks. When this network is under overload for reasons such as improper design, instantaneous swarm, components error and sudden reduction of processing capacity, its efficiency is considerably reduced. Overload occurs when the SIP proxy lacks sufficient CPU and memory resources to process all messages. Because the overload cannot be prevented completely, it is important to equip SIP proxies with an effective overload mitigation mechanism. In this paper, capabilities of transmission control protocol are used in transport layer to reduce SIP proxy overload through the proper allocation of proxy resources. Major activities in this field assume SIP on user datagram protocol, which practically does not result in optimal throughput. To evaluate this approach, an Asterisk open source proxy is used. Our implementation results in the real testbed indicate the efficiency improvement of Asterisk proxy under overload. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Due to the downside characteristics of Mobile Ad hoc Networks (MANETs) such as dynamic topology and energy consumption and control overhead, network clustering is one of the promising solutions. Cluster Based Routing Protocol (CBRP) is a robust and scalable routing protocol for MANETs. Clustering formation algorithm used in CBRP is a variation of simple lowest-ID algorithm in which the node with a lowest ID among its neighbors is elected as the Cluster head. Neglecting mobility and energy for selecting cluster head is one of the weakness points of the algorithm. In order to increase stability of the network and to prevent re-clustering an adaptive energy-aware Cluster Based Routing Protocol (AECBRP) is proposed. Two algorithms have been introduced in AECBRP as enhancement to the CBRP: improving the cluster formation algorithm by considering relative mobility, residual energy and connectivity degree metrics, and add in an efficient cluster maintenance algorithm based on the aggregate energy metric of cluster head. Using NS-2 we evaluate the rate of cluster-head changes, the normalization routing overhead and the packet delivery ratio. Comparisons denote that the proposed AECBRP has better performances with respect to the original CBRP and Cross-CBRP. [ABSTRACT FROM AUTHOR]

Copyright of Arabian Journal for Science & Engineering (Springer Science & Business Media B.V. ) is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: Due to the various features of Voice over Internet Protocol (VoIP), this technology has attracted the attention of many users in comparison with the traditional telephony system. However, with the growth of this technology, the security issues and protection of its users against different kinds of threats have been raised as an essential requirement. Session Initiation Protocol is a predominant protocol to initiate and terminate multimedia sessions in VoIP networks that provide simplicity and text‐based features. Despite its mentioned advantages, these features impose several vulnerabilities on VoIP networks. Denial of Service attack, as one of the most common attacks against VoIP networks, is also a noted security issue in the Internet Protocol platforms. In such attacks, the attacker tries to prevent service from authorized users by consuming server resources. These attacks can be launched by sending out‐of‐sequence messages, malformed messages, and flooding different kinds of messages. In this study, a new anomaly‐based method is presented for detection and prevention of these attacks. Normal traffic of a VoIP network is modeled by making a finite state machine, which is used for attack detection besides other proposed modules. Furthermore, a whitelist method is implemented using Bloom data structure for attack prevention. The proposed method is completely implemented and tested using different test scenarios. The obtained results show that by using proposed method, attacks can be detected more accurately with lower false ratios and delay in comparison with the existing methods. In this paper, a new anomaly‐based method is presented for detecting and preventing Denial of Service attacks due to out‐of‐sequence messages, malformed messages, and flooding messages. A finite state machine (FSM) is used to model the normal traffic of a VoIP network for detection purposes, and a whitelist was implemented using Bloom data structure for attack prevention. The proposed method is completely tested using different test scenarios, and the obtained results show the detection accuracy with lower false ratios and delay in comparison with the existing methods. [ABSTRACT FROM AUTHOR]