【作者】 王彬彦；

【导师】 涂序彦；

【作者基本信息】 北京邮电大学 ， 控制理论与控制工程， 2010， 硕士

【摘要】 P2P技术以分布式技术为基础,打破了传统的Client/Server模式。P2P网络中的每一个节点都处于平等的地位,同时扮演着服务器与客户机的角色,从而充分利用了主机设备上的边缘性网络资源。节点之间通过直接的互联来实现信息、处理器、存储甚至高速缓存等资源的全面共享,无需依赖集中式服务器的支持。P2P技术以其资源利用率高、网络扩展能力强、网络性能好、信息流动速率高、搜索功能强等优势,广泛应用于分布式计算、搜索功能、文件交换、协同工作等各个领域。目前,针对P2P领域相关的研究热点主要集中在P2P覆盖网络的组织结构的构建、P2P资源定位技术以及P2P系统的安全性三个方面。本文的研究工作主要从P2P网络中的信任管理以及P2P覆盖网络拓扑结构的构建两方面展开。首先,本文根据社会学、经济学等学科中对信任的概念以及信誉的相关研究成果,结合P2P网络的特点并分析了P2P网络中节点间信任关系所具有的性质,给出了本文对P2P网络中节点间信任关系及节点信誉的定义。在此基础上,对现有P2P网络中典型的信任模型进行了研究,对比分析了典型信任模型中存在的优势以及不足。接下来,本文针对P2P网络的无中心性、自组织性、拓扑结构的动态变化性,以及节点间的协作性等特点,依据人类社会以及计算机网络中普遍存在的小世界(Small World)现象,提出了一种基于节点信誉度的层状P2P网络信任管理机制。本文所提出信任管理机制采用分层的思想,充分结合和利用了P2P网络分布式的特性以及节点间的自组织性,推举网络中信誉度高的节点作为其他节点的信誉担保,来对网络中其他节点的信任信息进行管理。通过这种方法来提高整个网络的安全性,并且缓解了信誉度查询及更新过程中信任信息全网传播给网络带来的负担。根据这种分层管理的思想,本文设计了基于高效的DHT路由协议Kademlia实现的P2P网络系统,定义了网络节点间可信交互的交互机制,给出了节点信誉度发布、存储及查询的机制以及节点可信交互流程。最后,给出P2P网络中的信任评估模型。在本文的评估模型中,对网络中节点的恶意行为采取了一定的惩罚措施,有效的抑制和隔离了这些恶意行为,提高了网络的抗攻击性。另外,考虑了P2P网络中节点的异构性特点,给予网络中在线时间长、对网络贡献大的节点以较高的信誉度,使得网络中性能优越节点的处理能力得以充分的发挥。更多还原

【Abstract】 P2P which is based on the distributed technology, broke the traditional Client/Server model. Each node in a P2P network has similar functionalities and plays the role of a server and a client at the same time, make full use of the resources on the edge of networks. Peers in the P2P networks have a full share of the information, processor, memory and cache through direct connection but not dependent on the supports of the centralized server, which make the P2P network has the advantages of high resource utilization, strong expansion capability, good network performance, high speed of information flowing and powerful searching capacity. These made the P2P technology has a widely used in the distributed computing, searching, file exchange, team working and other fields. Related researches in the P2P field gradually carried out with the continuous expanding application of the P2P technology. At present, research of the P2P focus on these three aspects:Construction of the Topology of P2P Overlay, resource searching and location in the P2P network and security of the P2P System.The main research of this thesis is on the trust management of the P2P network and the construction of the P2P overlay topology.Firstly in this thesis, combined with characteristics of the P2P networks and analyzed feature of the trust relationship between P2P nodes, made the definition of trust and reputation in the P2P network according to related research findings of trust and reputation in the sociology, economics and other subjects. Then we made a study of the existing P2P trust models, contrastive analysis the advantage and shortage of these models. Secondly, considered the P2P networks have the characteristics of no central, self-organization, dynamic changes of topology as well as the nodes’interoperability, using the Small World theory exits in the human society and in the computer networks, we propose a layered P2P network trust management mechanisms which is based on the nodes’ global reputation. According to the layered P2P network trust management thinking described in this thesis, we make full use of the distributed and the self-organization features of the P2P network to elect the nodes who had higher global reputation to play the role of reputation guarantees of the other nodes and to manage their information of reputation. This layered P2P network trust management mechanisms enhances the security of the whole P2P system, reduces the transmission load brings from the trust information querying and updating, improves the ability of anti-attack by punishing the malicious acts or malicious recommend of the nodes.Based on the layer management proposed in this thesis we design the achievement mode of the layered P2P network trust management mechanisms we proposed using the DHT routing protocol, Kademlia. The achievement mode includes the aspects of the storage, query and update of the nodes’trust information and reliable interactive process between nodes.Finally we described the trust evaluation model of our P2P network. In this model, we take some punitive action on the nodes who have the malicious acts which controlled and isolated the these actions effectively. On the other hand, considering the heterogeneous of the nodes we give the higher trust value to the nodes who have longer online time and more contribution to the network, gives full play of processing capacity of these nodes.更多还原