Efficient Key Management and Distribution for MANET

Ad hoc networks are being used in applications ranging from disaster recovery to distributed collaborative entertainment applications. Ad hoc networks have become one of the most attractive solution for rapid deployment of interconnecting large number of mobile personal devices. The user community of mobile personal devices are demanding a variety of value added multimedia entertainment services. The popularity of peer group is increasing and one or some members of the peer group need to send data to some or all members of the peer group. The increasing demand for group oriented value added services is driving for efficient multicast service over ad hoc networks. Access control mechanisms need to be deployed to provide guarantee that the unauthorized users cannot access the multicast content. In this paper, we present a topology aware key management and distribution scheme for secure overlay multicast over MANET to address node mobility related issues for multicast key management. We use overlay approach for key distribution and our objective is to keep communication overhead low for key management and distribution. We also incorporate reliability using explicit acknowledgments with the key distribution scheme. Through simulations we show that the proposed key management scheme has low communication overhead for rekeying and improves the reliability of key distribution.

Mobile agent based TCP attacker identification in MANET using the traffic history (MAITH)

TCP attacks are the major problem faced by Mobile Ad hoc Networks (MANETs) due to its limited network and host resources. Attacker traceback is a promising solution which allows a victim to identify the exact location of the attacker and hence enables the victim to take proper countermeasure near attack origins, for forensics and to discourage attackers from launching the attacks. However, attacker traceback in MANET is a challenging problem due to dynamic network topology, limited network and host resources such as memory, bandwidth and battery life. We introduce a novel method of TCP attacker Identification in MANET using the Traffic History - MAITH. Based on the comprehensive evaluation based on simulations, we showed that MAITH can successfully track down the attacker under diverse mobile multi-hop network environment with low communication, computation, and memory overhead.

Emergent Intelligence Based QoS Routing in MANET

Mobile Ad hoc Networks (MANETs) are self-organized, infrastructureless, decentralized wireless networks consist of a group of heterogeneous mobile devices. Due to the inherent characteristics of MANE -Ts, such as frequent change of topology, nodes mobility, resource scarcity, lack of central control, etc., makes QoS routing is the hardest task. QoS routing is the task of routing data packets from source to destination depending upon the QoS resource constraints, such as bandwidth, delay, packet loss rate, cost, etc. In this paper, we proposed a novel scheme of providing QoS routing in MANETs by using Emergent Intelligence (El). The El is a group intelligence, which is derived from the periodical interaction among a group of agents and nodes. We logically divide MANET into clusters by centrally located static agent, and in each cluster a mobile agent is deployed. The mobile agent interacts with the nodes, neighboring mobile agents and static agent for collection of QoS resource information, negotiations, finding secure and reliable nodes and finding an optimal QoS path from source to destination. Simulation and analytical results show that the effectiveness of the scheme. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.ore/licenscs/by-nc-nd/4.0/). Peer-review under responsibility of the Conference Program Chairs

MANET下服务发现系统的实现、建模和优化

随着移动自组织网络（MANET）的日益普及，这种网络环境下的应用需求越来越多，服务发现系统是支撑这些应用的基础服务之一，它帮助用户在移动环境中发布、管理、发现和使用种类繁多的服务。 学术界和工业界对MANET下服务发现已经进行了很多探索和研究，但是已有研究多是构造有目录服务器的发现系统，它需要网络中存在能力比较强且稳定的节点充当目录服务器，这种模式并不适用于所有场景。到目前为止，无目录服务器的服务发现系统的构造相对较少且技术尚不成熟，存在较多问题需要解决。另外，针对不同的服务发现系统还没有一种普遍可行的系统建模和性能分析的方法。 本文针对MANET环境下不同的应用场景，改进了有目录服务器的发现系统SCN4M（Service CatalogNet for MANET），设计和实现了无目录服务器的发现系统SCN4M-DL（Service CatalogNet for MANET-DirectoryLess）。论文在SCN4M中引入了多种服务匹配策略包括近似匹配算法、基于正则表达式的匹配算法，同时提出了基于系统负载的自适应匹配策略调整机制，即通过引入请求队列队长作为控制变量，决定变换匹配策略的时机，以此加快或降低匹配处理速度。在SCN4M-DL中采用跨层设计思想，提出了面向区域的混合式地理位置路由算法，分阶段地使用贪心路由、面路由和面向服务发现的环形路由；并在此基础之上，实现了基于地理位置信息的服务注册、管理和发现。在两个系统中都使用了排队论对系统中的单个节点进行建模和优化。在SCN4M中通过扩展的有多服务速率的M/M+/1模型，得出了系统吞吐量、系统等待队长、系统平均调整次数的表达式，实际系统的运行结果验证了模型的适用性，论文依据模型给出了SCN4M在评价指标QoS指导下的优化的运行方案设计。在SCN4M-DL中，通过应用改进的串联排队论模型，将本地的发现过程分成了二个独立的阶段，然后，将SCN4M中的M/M+/1模型成功应用于第二阶段，论文也给出了SCN4M-DL的优化方案。

MANET下自适应服务发现系统的设计与实现

MANET（Mobile Ad Hoc Network）环境中设备的多样性、无线网络和用户 的移动性及动态性，需要服务发现系统具有自适应能力，才能为用户提供可用的 服务，提高用户对系统的满意程度。本文在地理路由基础上，设计和实现了 MANET 下自适应服务发现系统 SCN4M-H（Service CatlogNet For MANET – Hybrid），SCN4M-H 致力于解决如何在低开销条件下发现可用服务以及全面支持 节点的移动性和动态性。同时，针对动态的网络环境，提供了动态体系结构的支 持机制，以及面向位置的服务发现。 为了应对网络中存在大量频繁移动的节点状况，SCN4M-H 采用了基于环的 服务发现机制。服务以及对应的服务描述，首先会被映射到一个具体的地理位置， 之后此服务和服务描述将被注册到此位置上的节点，或者相应圆环内的节点集合 上。随后，服务发现请求也按类似方式映射到一个地理位置，并被转发到此地理 位置或附近的节点上执行服务查找。这种方式可以避免基于无目录的服务发现系 统通常由于采用请求的泛洪转发而导致的冗余消息传输问题。SCN4M-H 也考虑 了 MANET 环境下节点的移动、节点的动态加入/离开、以及主动服务注册/服务 注销情况下的服务的可用性问题。在 SCN4M-H 中，服务是绑定到一个确定的地 理位置，所以，保证服务的可用性问题转变为确保在服务所对应的物理位置或者 临近位置找到此服务的问题。SCN4M-H 采用可配置的服务刷新策略来达到及时 发现当前可用服务的目的。采用基于圆环的服务注册和发现机制，消除基于周界 机制所带来的高开销，同时也保证了良好的发现成功率。同时，鉴于动态网络环 境中往往存在着相对稳定且资源丰富的节点，本文提出了基于志愿者节点的服务 发现机制，使得志愿者在一定地理范围内承担起临时目录服务器的作用。而且， 给出了相应的服务备份和模式转换机制，保证当志愿者节点离开系统后，原先注 册的服务依然可用。本文还为用户提供了面向位置的服务发现，采用了基于最小 代价树的地理路由协议，以满足用户对特定范围内服务的发现需求。 为了对 SCN4M-H 进行全面评估，本文进行了大量的实验，实验结论显示， SCN4M-H 能在低开销内让用户获得满意的可用服务发现成功率，当系统存在志 愿者节点的情况下，系统能以更少的系统开销获得更好的服务发现成功率，同时 能以良好的性能和可接受的开销提供面向位置的服务发现功能。

MANET中TCP Vegas拥塞控制的端到端改进方法

TCP Vegas通过往返时间的最小值baseRTT来进行拥塞控制,因此获取准确baseRTT的值至关重要.在MANET中,不断变化的网络拓扑会导致baseRTT的测量出现严重偏差,从而降低了吞吐量,而TCP Vegas在拥塞避免阶段发生路由变化但没有引起丢包或失序现象时,已有的端到端启发式方案很难进行识别.采用回落探测方法识别路由变化,进而调节往返时间的最小值以改善TCP Vegas拥塞控制算法在MANET中的性能.

Supporting Predicate Routing in DTN over MANET

We consider a Delay Tolerant Network (DTN) whose users (nodes) are connected by an underlying Mobile Ad hoc Network (MANET) substrate. Users can declaratively express high-level policy constraints on how "content" should be routed. For example, content may be diverted through an intermediary DTN node for the purposes of preprocessing, authentication, etc. To support such capability, we implement Predicate Routing [7] where high-level constraints of DTN nodes are mapped into low-level routing predicates at the MANET level. Our testbed uses a Linux system architecture and leverages User Mode Linux [2] to emulate every node running a DTN Reference Implementation code [5]. In our initial prototype, we use the On Demand Distance Vector (AODV) MANET routing protocol. We use the network simulator ns-2 (ns-emulation version) to simulate the mobility and wireless connectivity of both DTN and MANET nodes. We show preliminary throughput results showing the efficient and correct operation of propagating routing predicates, and as a side effect, the performance benefit of content re-routing that dynamically (on-demand) breaks the underlying end-to-end TCP connection into shorter-length TCP connections.

PreDA: Predicate Routing for DTN Architectures over MANET

We consider a Delay Tolerant Network (DTN) whose users (nodes) are connected by an underlying Mobile Ad hoc Network (MANET) substrate. Users can declaratively express high-level policy constraints on how “content” should be routed. For example, content can be directed through an intermediary DTN node for the purposes of preprocessing, authentication, etc., or content from a malicious MANET node can be dropped. To support such content routing at the DTN level, we implement Predicate Routing [1] where high-level constraints of DTN nodes are mapped into low-level routing predicates within the MANET nodes. Our testbed [2] uses a Linux system architecture with User Mode Linux [3] to emulate every DTN node with a DTN Reference Implementation code [4]. In our initial architecture prototype, we use the On Demand Distance Vector (AODV) routing protocol at the MANET level. We use the network simulator ns-2 (ns-emulation version) to simulate the wireless connectivity of both DTN and MANET nodes. Preliminary results show the efficient and correct operation of propagating routing predicates. For the application of content re-routing through an intermediary, as a side effect, results demonstrate the performance benefit of content re-routing that dynamically (on-demand) breaks the underlying end-to-end TCP connections into shorter-length TCP connections.

An Effective Path Protection Method to Attain the Route Stability in MANET

With the increasing popularity of wireless network and its application, mobile ad-hoc networks (MANETS) emerged recently. MANET topology is highly dynamic in nature and nodes are highly mobile so that the rate of link failure is more in MANET. There is no central control over the nodes and the control is distributed among nodes and they can act as either router or source. MANTEs have been considered as isolated stand-alone network. Node can add or remove at any time and it is not infrastructure dependent. So at any time at any where the network can setup and a trouble free communication is possible. Due to more chances of link failures, collisions and transmission errors in MANET, the maintenance of network became costly. As per the study more frequent link failures became an important aspect of diminishing the performance of the network and also it is not predictable. The main objective of this paper is to study the route instability in AODV protocol and suggest a solution for improvement. This paper proposes a new approach to reduce the route failure by storing the alternate route in the intermediate nodes. In this algorithm intermediate nodes are also involved in the route discovery process. This reduces the route establishment overhead as well as the time to find the reroute when a link failure occurs.

Littera Scripta Manet: formas y funciones del archivo en el Imperio de los Austrias. Simancas, Roma, Quito y Cuenca (Estudios)

El artículo explora el papel de los archivos en el Imperio de los Austrias, durante la edad protomoderna, en ambos lados del Atlántico. Con ese propósito se analizan las diferentes tareas que incumbían a los archivos en el siglo XVI y XVII. Se examinan el archivo de la ciudad de Cuenca (actual Ecuador) en el ámbito municipal, el de la Audiencia de Quito en el ámbito regional, el archivo de Simancas (Castilla) en el nivel real y, por último, el archivo en la embajada española en Roma. También se ofrecen reflexiones sobre el carácter y las particularidades de los repositorios documentales, prestando especial atención a la escritura como medio de gobierno.

GOM : new genetic optimizing model for broadcasting tree in MANET

Data broadcasting in a mobile ad-hoc network (MANET) is the main method of information dissemination in many applications, in particular for sending critical information to all hosts. Finding an optimal broadcast tree in such networks is a challenging task due to the broadcast storm problem. The aim of this work is to propose a new genetic model using a fitness function with the primary goal of finding an optimal broadcast tree. Our new method, called Genetic Optimisation Model (GOM) alleviates the broadcast storm problem to a great extent as the experimental simulations result in efficient broadcast tree with minimal flood and minimal hops. The result of this model also shows that it has the ability to give different optimal solutions according to the nature of the network.

Multimedia stream rate control over MANET based on router feedback

Streaming applications over Mobile Ad-hoc Networks (MANET) require a smooth transmission rate. The Internet is unable to provide this service during traffic congestion in the network. Designing congestion control for these applications is challenging, because the standard TCP congestion control mechanism is not able to handle the special properties of a shared wireless multi hop channel well. In particular, the frequent changes to the network topology and the shared nature of the wireless channel pose major challenges. In this paper, we propose a novel approach, which allows a quick increase of throughput by using explicit feedback from routers.