一种针对共谋攻击的I2P节点选择优化算法

随着网络技术的迅猛发展,人们的个人隐私保护意识逐渐提高,越来越多的用户为了保护自己的隐私安全,选择在暗网与他人进行互联沟通。I2P作为当前使用最广泛的匿名网络之一,虽然有着较好的保证网络内用户匿名性的机制,但是也有不足。在简单介绍I2P技术原理的基础上,分析I2P容易受到的网络攻击手段,提出了一种针对共谋攻击的节点选择优化算法,能够有效减少网络攻击对I2P网络匿名性的影响。     

GPM: A generic and scalable P2P model that optimizes tree depth for multicast communications

Group communications (real‐time and non‐real‐time) refer to one‐to‐many or many‐to‐many communications. On the one hand, multicast is considered as an appropriate solution for supporting group communication‐oriented applications (we distinguish IP network multicast from application layer multicast). On the other hand, peer‐to‐peer model tends to be a good candidate for supporting today Internet applications (e.g. P2P IPTV, P2P VoIP, etc.). In this context, P2P has attracted significant interest in the recent years. This is mainly due to its properties that also make P2P well adapted to today social networks. In this paper, we propose GPM (Generic P2P Multicast): a novel generic and scalable approach, that optimizes multicast tree depth in P2P networks (structured and unstructured), and contributes to control the network overlay latency. For multicast tree construction, the approach we propose is based on a distributed algorithm using a specific data structures (adjacency and forwarding matrixes). GPM model inherits from P2P attributes such as scalability, flexibility and fault tolerance, while taking into consideration the respective characteristics of one‐to‐many and many‐to‐many type of applications. We also give a performance evaluation for validation and comparison purposes while considering some main existing application layer multicast protocols. Copyright © 2011 John Wiley & Sons, Ltd.     

A distributed utility‐based scheduling for peer‐to‐peer video streaming over wireless networks

Interactive multimedia applications such as peer‐to‐peer (P2P) video services over the Internet have gained increasing popularity during the past few years. However, the adopted Internet‐based P2P overlay network architecture hides the underlying network topology, assuming that channel quality is always in perfect condition. Because of the time‐varying nature of wireless channels, this hardly meets the user‐perceived video quality requirement when used in wireless environments. Considering the tightly coupled relationship between P2P overlay networks and the underlying networks, we propose a distributed utility‐based scheduling algorithm on the basis of a quality‐driven cross‐layer design framework to jointly optimize the parameters of different network layers to achieve highly improved video quality for P2P video streaming services in wireless networks. In this paper, the quality‐driven P2P scheduling algorithm is formulated into a distributed utility‐based distortion‐delay optimization problem, where the expected video distortion is minimized under the constraint of a given packet playback deadline to select the optimal combination of system parameters residing in different network layers. Specifically, encoding behaviors, network congestion, Automatic Repeat Request/Query (ARQ), and modulation and coding are jointly considered. Then, we provide the algorithmic solution to the formulated problem. The distributed optimization running on each peer node adopted in the proposed scheduling algorithm greatly reduces the computational intensity. Extensive experimental results also demonstrate 4–14 dB quality enhancement in terms of peak signal‐to‐noise ratio by using the proposed scheduling algorithm. Copyright © 2015 John Wiley & Sons, Ltd.     

一种P2P网络信任模型METrust

 Peer-to-Peer(P2P)网络的异构性、匿名性、自治性等特点导致了一些安全问题,比如伪造、诋毁、协同作弊等,影响了服务质量.提出了一种基于推荐的P2P网络信任模型METrust,节点在网络中拥有唯一的推荐可信度,引入了更新幅度和更新力度两个参数来更新推荐可信度.给出了节点推荐可信度的更新算法;节点根据评价标准的相似程度选择推荐,其中节点的评价标准通过AHP(Analytic Hierarchy Process)方法确定.仿真实验表明,METrust信任模型可以识别恶意节点,有效提高P2P网络的服务质量.     

I2P匿名通信流量特征分析与识别

由于匿名通信网络具有非常强的匿名性,因此越来越多的人使用匿名通信网络发布违法信息,给监管带来了很大挑战。识别匿名通信网络的流量对监管匿名通信网络具有重要意义,但目前很少有针对I2P的流量识别研究。因此,通过对I2P数据流进行深入分析,得到I2P数据流的特征,并在此基础上设计实现了I2P流量识别算法。实验结果表明,该算法具有较高的精确度和召回率,可以有效识别I2P流量。     

Exploring the accuracy of capturing snapshots in large‐scale P2P IPTV systems

With the growing maturity of peer‐to‐peer (P2P) technology, Internet protocol television (IPTV) applications based on that gained great success commercially and have attracted more and more attentions from both industry and academia. Currently, the active measurement method based on crawler technology is the most popular and effective one to study P2P IPTV systems. Existing measurement results revealed that accuracy of captured overlay snapshots depends on the crawling speed of crawler system. In order to capture more accurate overlay snapshots of P2P IPTV system, we developed a very fast and efficient distributed crawler system using the distributed architecture and peer degree‐rank mechanism. In this paper, we first introduce the architectures of PPTV channel‐list resource distribution and the whole system, which is the most popular and largest instance of P2P IPTV applications nowadays. Subsequently, this paper evaluates the crawling results of two dedicated crawlers capturing from peer‐list servers and ordinary peers, respectively. Finally, we propose a fast and accurate dedicated crawler system based on distributed architecture and peer degree rank for PPTV. The experiment results show that the performance of our distributed crawler system is much better than other existing crawler systems. Specifically, our distributed crawler can track a very popular channel with about 7200 online users in 30 s. It is also reasonable to believe that our distributed crawler system can capture complete overlay snapshots. To the best of our knowledge, our study work is the first to explore capturing accurate overlay snapshots of large‐scale P2P IPTV applications. Our crawler system can provide a good solution for capturing more accurate overlay snapshots of PPTV system and can also be used to help researchers to design crawler systems for other P2P IPTV systems. Copyright © 2015 John Wiley & Sons, Ltd.     

An efficient method of P2P traffic identification based on wavelet packet decomposition and kernel principal component analysis

Peer‐to‐peer (P2P) traffic identification is currently an important challenge to network management and measurement. Many approaches based on statistics have been proposed to identify P2P traffic. However, flow features extracted by traditional methods are rough and one‐sided, which might lead to inaccuracy identification of network traffic. Besides, P2P traffic has too many statistical features, which is a challenge to the time complexity and space complexity of the classifier. This work focuses on the study of flow features. First, micro features of flow signals are extracted based on wavelet packet decomposition, and we combine them with the traditional features into combination features. The experimental results show that combination features have better performance than traditional features for P2P traffic identification, and 16 kinds of wavelet functions were tested to find the best one. Second, a feature reduction algorithm based on improved kernel principal component analysis is provided. The results show that the feature reduction algorithm proposed in this paper plays good performance to P2P traffic identification, because it could greatly reduced the number of features while having no affection on identification accuracy. Copyright © 2012 John Wiley & Sons, Ltd.     

基于朋友聚类的语义覆盖网构建方法研究

P2P网络是一种极具潜力的信息共享方式,当前对于它的研究成为网络技术的热点问题.P2P网络的分布、分散、组织困难等特点,使P2P网络在应用中有很多不足,这就要求提高P2P网络的应用效率,优化查询过程等.以一个无结构的,可以用无向图来表示的P2P网络为基础,首先构造了一个描述节点上文件的元数据模型,在这个模型的基础上进行语义聚类,并定义了一个聚类特征向量来描述生成的聚类.在完成本地节点上的聚类以后,再进一步进行节点间的聚类,提出了朋友聚类的概念,基于朋友聚类构建语义覆盖网,它可以大大提高查询效率.     

P2P网络层次化信任模型

大规模文件共享P2P网络中节点之间发生重复交易的可能性较小而难以建立信任关系,从而导致P2P网络容易受到恶意节点攻击。针对该问题本文提出了基于群组的P2P网络层次化信任模型。该信任模型将信任关系划分为群组之间的信任关系,群组与节点之间的信任关系和节点之间的信任关系3个层次。节点利用本地信任信息或所属群组的推荐信任确定给定节点的信任值。仿真分析表明,该信任模型能够有效识别恶意节点,使P2P网络中合作节点具有较高的成功请求率。     

在P2P网络下Sybil攻击的研究与防范

P2P网络的自由开放特性使得节点可随意创建身份加入系统，但这也会引发Sybil攻击。文章设计了一种新节点身份的认证方案，提出新节点身份需暴力破解单向函数的计算难题才能加入网络。因此增加了用户创建新节点身份的代价，使得用户无法随意创建身份，从而达到了验证新节点身份的目的，避免系统受到攻击。     

Extending P2PMesh: topology‐aware schemes for efficient peer‐to‐peer data sharing in wireless mesh networks

Wireless mesh networks (WMNs) have emerged as a promising technology that provides low‐cost broadband access to the Internet for fixed and mobile wireless end users. An orthogonal evolution in computer networking has been the rise of peer‐to‐peer (P2P) applications such as P2P data sharing. It is of interest to enable effective P2P data sharing in this type of networks. Conventional P2P data sharing systems are not cognizant of the underlying network topology and therefore suffer from inefficiency. We argue for dual‐layer mesh network architecture with support from wireless mesh routers for P2P applications. The main contribution of this paper is P2PMesh: a topology‐aware system that provides combined architecture and efficient schemes for enabling efficient P2P data sharing in WMNs. The P2PMesh architecture utilizes three schemes: (i) an efficient content lookup that mitigates traffic load imbalance at mesh routers; (ii) an efficient establishment of download paths; and (iii) a data transfer protocol for multi‐hop wireless networks with limited capacity. We note here that the path establishment and data transfer schemes are specific to P2P traffic and that other traffic would use routes determined by the default routing protocol in the WMN. Simulation results suggest that P2PMesh has the potential to improve the performance of P2P applications in a wireless multi‐hop setting; specifically, we focused on data sharing, but other P2P applications can also be supported by this approach. Copyright © 2011 John Wiley & Sons, Ltd.     

On the resilience of P2P botnet footprints in the presence of legitimate P2P traffic

Botnet is a distributed platform for illegal activities severely threaten the security of the Internet. Fortunately, although their complicated nature, bots leave some footprints during the C&C communication that have been utilized by security researchers to design detection mechanisms. Nevertheless, botnet designers are always trying to evade detection systems by leveraging the legitimate P2P protocol as C&C channel or even mimicking legitimate peer‐to‐peer (P2P) behavior. Consequently, detecting P2P botnet in the presence of normal P2P traffic is one of the most challenging issues in network security. However, the resilience of P2P botnet detection systems in the presence of normal P2P traffic is not investigated in most proposed schemes. In this paper, we focused on the footprint as the most essential part of a detection system and presented a taxonomy of footprints utilized in behavioral P2P botnet detection systems. Then, the resilience of mentioned footprints is analyzed using three evaluation scenarios. Our experimental and analytical investigations indicated that the most P2P botnet footprints are not resilient to the presence of legitimate P2P traffic and there is a pressing need to introduce more resilient footprints.     

Adaptive video protection in large scale peer‐to‐peer video streaming over mobile wireless mesh networks

Because video streaming over mobile handheld devices has been of great interest, the necessity of introducing new methods with low implementation cost and scalable infrastructures is a strong demand of the service. In particular, these requirements are present in popular wireless networks such as wireless mesh networks (WMN). Peer‐to‐peer (P2P) networks promise an efficient scalable network infrastructure for video streaming over wired and wireless networks. Limited resources of the peers in P2P networks and high error rate in wireless channels make it more challenging to run P2P streaming applications over WMNs. Therefore, it is necessary to design efficient and improved error protection methods in P2P video streaming applications over WMNs. In this paper, we propose a new adaptive unequal video protection method specially intended for large scale P2P video streaming over mobile WMNs. Using this method, different frames have different priorities in receivers along the recovery process. Moreover, we precisely and completely evaluate different aspects related to frame protection in these networks using five important performance metrics including video distortion, late arrival distortion, end‐to‐end delay, overhead and initial start‐up delay. The results obtained from a precise simulation in OMNeT++ show that the proposed adaptive method significantly outperforms other solutions by providing better video quality on mobile wireless nodes. Copyright © 2015 John Wiley & Sons, Ltd.     

Adaptive traffic sampling for P2P botnet detection

Peer‐to‐peer (P2P) botnets have become one of the major threats to network security. Most existing botnet detection systems detect bots by examining network traffic. Unfortunately, the traffic volumes typical of current high‐speed Internet Service Provider and enterprise networks are challenging for these network‐based systems, which perform computationally complex analyses. In this paper, we propose an adaptive traffic sampling system that aims to effectively reduce the volume of traffic that P2P botnet detectors need to process while not degrading their detection accuracy. Our system first identifies a small number of potential P2P bots in high‐speed networks as soon as possible, and then samples as many botnet‐related packets as possible with a predefined target sampling rate. The sampled traffic then can be delivered to fine‐grained detectors for further in‐depth analysis. We evaluate our system using traffic datasets of real‐world and popular P2P botnets. The experiments demonstrate that our system can identify potential P2P bots quickly and accurately with few false positives and greatly increase the proportion of botnet‐related packets in the sampled packets while maintain the high detection accuracy of the fine‐grained detectors.     

HPSIN: a new hybrid P2P spatial indexing network

Geographic information system(GIS)is increasingly managing very large sets of data,hence a centralized data index may not always provide the most scalable solution.Recently,the peer to peer(P2P)networks have become very popular for sharing information in a totally decentralized manner.In this paper,a new hybrid P2P spatial indexing network(HPSIN)is proposed,which combines distributed quad-tree with distributed Hash table(DHT)based Chord network to maintain both query efficiency and system load balance.In addition,a simple theoretical model based on opened queueing network for HPSIN is established.Assuming each peer as M/M/1 queueing processor in the model,fundamental characteristics of the system is captured,and expression of average query delay is obtained in close form.The theoretical analysis and numerical computing results show that there exists an optimum point of tradeoff between efficiency and load balance.By setting a proper value of start index level ls for different network scale and query rate,HPSIN will achieve the minimum overall query delay,therefore,can adapt to different P2P application environments.     

Peer-to-Peer multimedia sharing based on social norms

Designing incentive schemes for Peer-to-Peer (P2P) multimedia sharing applications, where the participating peers find it in their self-interest to contribute resources rather than to “free-ride”, is challenging due to the unique features exhibited by such networks: large populations of anonymous peers interacting infrequently, asymmetric interests of peers, network errors, multiple concurrent transactions, low-cost implementation requirements, etc. In this paper, to address these challenges, we design and rigorously analyze a new family of incentive protocols that utilizes social norms. In the proposed protocols, each peer maintains a reputation reflecting its past behaviors in the P2P system (i.e. whether the peers have followed or not the social strategy prescribed by the social norm), and the social norm rewards and punishes peers depending on their reputations. We first define the concept of a sustainable social norm, under which no peer has an incentive to deviate from the social strategy prescribed by the protocol. We then formulate the problem of designing optimal social norms, which selects the social norm that maximizes the network performance among all sustainable social norms. In particular, we prove that, given the P2P network and peers' characteristics, social norms can be designed such that it becomes in the self-interest of peers to contribute their contents to the network rather than to free-ride. We also investigate the impact of various punishment schemes on the social welfare as well as how should the optimal social norms be designed if altruistic and malicious peers are active in the network. Our results show that optimal social norms are capable of deterring free-riding behaviors and providing significant improvements in the sharing efficiency of multimedia P2P networks.     

P2P业务流量特性及其对Web业务的影响

近年来各种P2P应用不断出现及演进,P2P应用正逐渐成为下一代互联网的杀手级应用。但同时P2P消耗了Internet的大部分带宽,造成了网络技术服务商(ISP)接入网络的拥塞,从而使传统Internet应用性能受到严重影响。从P2P流数量、服务器负载、网络瓶颈点分布、往返时间(RTT)的异构特性等方面可以看出,P2P流量消耗了巨大的网络带宽,影响了传统Internet业务的性能,增加了运营成本。利用P2P流量和Web流量的集成模型,可以量化分析P2P流对Web流的影响,使网络运营商可以在网络瓶颈点对P2P连接数进行优化和调整,从而有效地控制P2P流量。NS2仿真结果较好地验证了该模型的有效性。     

An efficient anonymous communication protocol for peer-to-peer applications over mobile ad-hoc networks

An efficient anonymous communication protocol, called MANET Anonymous Peer-to-peer Communication Protocol (MAPCP), for P2P applications over mobile ad-hoc networks (MANETs) is proposed in this work. MAPCP employs broadcasts with probabilistic-based flooding control to establish multiple anonymous paths between communication peers. It requires no hop-by-hop encrypt ion/decryption along anonymous paths and, hence, demands lower computational complexity and power consumption than those MANET anonymous routing protocols. Since MAPCP builds multiple paths to multiple peers within a single query phase without using an extra route discovery process, it is more efficient in P2P applications. Through analysis and extensive simulations, we demonstrate that MAPCP always maintains a higher degree of anonymity than a MANET anonymous single-path routing protocol in a hostile environment. Simulation results also show that MAPCP is resilient to passive attacks     

X‐Region: A framework for location privacy preservation in mobile peer‐to‐peer networks

While enjoying various LBS (location‐based services), users also face the threats of location privacy disclosure. This is because even if the communications between users and LBS providers can be encrypted and anonymized, the sensitive information inside LBS queries may disclose the exact location or even the identity of a user. The existing research on location privacy preservation in mobile peer‐to‐peer (P2P) networks assumed that users trust each other and directly share location information with each other. Nonetheless, this assumption is not practical for most of the mobile P2P scenarios, for example, an adversary can pretend to be a normal user and collect the locations of other users. Aiming at this issue, this paper presents x‐region as a solution to preserve the location privacy in a mobile P2P environment where no trust relationships are assumed amongst mobile users. The main idea is to allow users to share a blurred region known as x‐region instead of their exact locations so that one cannot distinguish any user from others inside the region. We propose a theoretical metric for measuring the anonymity property of x‐region, together with three algorithms for generating an x‐region, namely, benchmark algorithm, weighted expanding algorithm, and aggressive weighted expanding algorithm. These algorithms achieve the anonymity and QoS requirements with different strategies. Our experiments verify the performance of the algorithms against three key metrics. Copyright © 2013 John Wiley & Sons, Ltd.