Double‐layer P2P networks supporting semantic search and keeping scalability

In peer‐to‐peer (P2P) networks, with the aim to support semantic search and keep scalability at the same time, a novel double‐layer P2P protocol is proposed. Firstly, keywords representing resource characteristics are compressed into bloom filters and structured P2P layer is constructed. Secondly, through analyzing one's bloom filters, each node extracts its interest, which is represented by a characteristic vector V. After obtaining common interest among nodes through comparing their Vs, a small‐world model is constructed, and another unstructured P2P layer is obtained. Consequently, on the basis of the decentralized architecture, a double‐layer semantic search P2P protocol is structured. When objective resource is being located, its similarity to local interest is used to determine whether it should be located in unstructured P2P semantic layer or structured layer adaptively, which not only improves search efficiency but also supports semantic location more widely. Copyright © 2013 John Wiley & Sons, Ltd.     

Slack time–based scheduling scheme for live video streaming in P2P network

Nowadays, peer‐to‐peer network plays a significant role in data transfer and communication. The past few years have witnessed considerable growth in this area because of its inherent advantages. Peer‐to‐peer live streaming has a significant impact on video transmission over the Internet. Major factors that influence the performance of P2P live streaming are overlay construction and scheduling strategies. Although, a large number of scheduling schemes are developed but none of them is comprehensive enough to provide solutions to live streaming issues. These suffer from substantial delay and low video quality at the receiver side. In this paper, a new start‐up–based selection procedure and slack time–based scheduling scheme is proposed. The start‐up selection procedure defines the start‐up buffer location for new peer, and the scheduling scheme selects both the chunk and peers. The proposed scheduling scheme uses both push and pull priority–based strategies. The simulation results of the proposed approach demonstrates significant improvement in both the network performance and video quality at the receiver side. It is observed that playback delay, startup delay, and end‐to‐end delay in the network are reduced and quality of the video at receiver side is improved as the distortion and frame loss ratio is decreased.     

基于Web应用的网络安全漏洞发现与研究

随着Web应用系统的不断普及,越来越多的网络安全漏洞被发现,给人们的工作和生活都造成了极大的威胁。Web安全漏洞可以分成基于Web应用的网络安全漏洞和基于Web平台的网络安全漏洞两种。文章通过阐述这两种网络安全漏洞的现状及安全误区,总结几种常见的安全漏洞攻击方法,并提出有效措施以防范黑客攻击漏洞,维护网络系统的安全。     

P2broadcast: a hierarchical clustering live video streaming system for P2P networks

This work describes a novel live video streaming system for P2P networks, referred to as P2broadcast. The video streaming service has bandwidth requirements to guarantee presentation quality. Therefore, a scalable strategy to quickly find a path from a media server to a client with abundant bandwidth is very important. A common approach in the literature is the bandwidth first (BF) scheme, which allows a newcomer to adopt a BF tree traversal scheme to find its parent peer on the P2P overlay tree to retrieve the media content. The BF scheme is likely to build a deep overlay tree, resulting in long start‐up latency as the number of peers on the overlay tree grows. P2broadcast reduces start‐up latency by organizing peers into hierarchical clusters and making the overlay tree become a ‘short‐and‐wide’ tree. The hierarchical clustering structure enables a newcomer to find its parent peer among the set of peers that are more likely to provide large available bandwidth only. Limiting the set of potential parent peers not only reduces start‐up latency but also improves the system availability. Additionally, unlike the BF scheme that only concerns available bandwidth, P2broadcast utilizes a cost function to evaluate the appropriateness of a potential parent peer. The cost function considers the depth of the newcomer on the overlay tree, making the overlay tree become a short‐and‐wide tree. In addition to start‐up latency reduction, the short‐and‐wide tree feature also alleviates the service interruption probability due to the leaving or failure of a peer. Our simulation results show that P2broadcast greatly outperforms the BF scheme in terms of system availability, and achieves around 66% savings in start‐up latency and 10% decrement in service interruption probability. Copyright © 2005 John Wiley & Sons, Ltd.     

P2P网络Peer访问Web Service的研究和实现

文章首先简要介绍了P2P网络和Web Service的技术背景,接着提出了P2P网络与Web Service集成的思想,为此提出Web Service Broker的概念,从而实现P2P网络Peer透明访问Web Service。     

Access control mechanism using flexible multi‐layer structure for mesh‐based P2P live streaming systems

When thousands of new peers seek to join the peer‐to‐peer (P2P) system within a very short time (i.e., the so‐called flash crowd event), most of the peers suffer a long startup delay as a result of peer over‐competition. Accordingly, recent studies have proposed a slot‐based user access control (UAC) mechanism, which periodically admits a certain number of new peers to the system, and a user batch join (UBJ) mechanism, which preconstructs the new peers into a fixed‐size tree structure before peer join process. However, in the UAC mechanism, it is difficult to determine the optimal time slot length; while in the UBJ mechanism, it is difficult to determine the optimal tree size. Accordingly, the present study proposes a structured access control (SAC) mechanism, in which the new‐arriving peers are preconstructed to a flexible multilayer structure to overcome the limitation of a fixed‐size tree structure, and the number of peers in each layer of the structure is determined based on a consideration of the remaining upload bandwidth of the P2P system. Based on the assumption of a heterogeneous upload bandwidth capability of the peers, an analytical model is derived to describe the growth behavior of a P2P system with access control. It is shown that the simulation results for the growth rate of a P2P system based on the SAC mechanism are in good agreement with those obtained from the analytical model. In addition, the simulation results show that the SAC mechanism outperforms the UAC and UBJ mechanisms in terms of a more rapid system growth and a shorter average startup delay. Copyright © 2016 John Wiley & Sons, Ltd.     

GaMe‐PLive: a new game theoretic mechanism for P2P live video streaming

GaMe‐PLive is a game theoretical framework for peer‐to‐peer live video streaming. Prevention of free‐riding and minimization of loss rate in video data transmission are the important objectives of the proposed framework. GaMe‐PLive is also extremely evasive about overhead of extra control messages exchange. At first, a static game with complete information between peers is described, which models the peer's interactive decision process for acceptance/rejection of a video chunk request. All peers repeatedly play this game during video playback periodically. Afterwards, the proposed game is analyzed to obtain a Nash equilibrium, which determines a peer's best strategic response for participation in the video chunk distribution. It will be proved that by applying some simple and feasible conditions, the desired objectives can be reached. The experimental results reveal that the proposed system has been successful in detecting free‐riders with negligible false negative and false positive rate. Also, tolerable loss chunk percentage has been satisfied in all performed tests. Besides, an interesting social norm emerges in GaMe‐PLive: Less participation leads to more missing chunks. GaMe‐PLive will be proven to be quite resistant against cheating peers. The proposed framework displays high performance even if there is not a video server with high upload bandwidth. Copyright © 2015 John Wiley & Sons, Ltd.     

Credit risk assessment of P2P lending platform towards big data based on BP neural network

Peer-to-peer (P2P) lending platform plays a significant role in modern financial systems. However, due to improper supervision, credit risk is inevitable. In this paper, we analyze the traditional financial risk and information technology risk of P2P lending platform. In order to evaluate the performance of assessment algorithms, we present a BP neural network-based algorithm for lending risk assessment. To achieve our task, we crawled large-scale lending data for 2015–2019. Logistic regression is used to compare with BP neural network method. Experimental results show that BP neural network-based algorithm outperforms traditional Logistic regression algorithm and the proposed method can effectively reduce investor risk.     

A distributed adaptive landmark clustering algorithm based on mOverlay and learning automata for topology mismatch problem in unstructured peer‐to‐peer networks

Peer‐to‐peer networks are overlay networks that are built on top of communication networks that are called underlay networks. In these networks, peers are unaware of the underlying networks, so the peers choose their neighbors without considering the underlay positions, and therefore, the resultant overlay network may have mismatches with its underlying network, causing redundant end‐to‐end delay. Landmark clustering algorithms, such as mOverlay , are used to solve topology mismatch problem. In the mOverlay algorithm, the overlay network is formed by clusters in which each cluster has a landmark peer. One of the drawbacks of mOverlay is that the selected landmark peer for each cluster is fixed during the operation of the network. Because of the dynamic nature of peer‐to‐peer networks, using a non‐adaptive landmark selection algorithm may not be appropriate. In this paper, an adaptive landmark clustering algorithm obtained from the combination of mOverlay and learning automata is proposed. Learning automata are used to adaptively select appropriate landmark peers for the clusters in such a way that the total communication delay will be minimized. Simulation results have shown that the proposed algorithm outperforms the existing algorithms with respect to communication delay and average round‐trip time between peers within clusters. Copyright © 2015 John Wiley & Sons, Ltd.     

Smart WLAN Discovery for Power Saving of Dual‐Mode Terminals

Dual‐mode terminals (DMTs) equipped with cellular and WLAN interfaces have become popular in recent years. Users of DMTs can enjoy high‐speed WLAN Internet access and wide area Internet access to cellular networks. However, a DMT may consume power inefficiently when discovering a WLAN with inherently limited service coverage. In this letter, we propose to use smart WLAN discovery (SWD) to minimize the power consumption required for WLAN discovery. To minimize the power consumption of a DMT, an SWD DMT activates its WLAN interface only when the DMT transfers data within the WLAN coverage area. The simulation results of SWD show an improved power‐saving performance compared to previous WLAN discovery schemes.     

A reconstructing approach to end‐to‐end network traffic based on multifractal wavelet model

This paper studies the reconstructing method of end‐to‐end network traffic. Due to the development of current communication networks, our networks become more complex and heterogeneous. Meanwhile, because of time‐varying nature and spatio‐temporal correlations of the end‐to‐end network traffic, to obtain it accurately is a great challenge. We propose to exploit discrete wavelet transforms and multifractal analysis to reconstruct the end‐to‐end network traffic from time–frequency domain. First, its time–frequency properties can be characterized in detail by discrete wavelet transforms. And then, we combine discrete wavelet transforms and multifractal analysis to reconstruct end‐to‐end network traffic from link loads. Furthermore, our method needs to measure end‐to‐end network traffic to build the statistical model named multifractal wavelet model. Finally, simulation results from the real backbone networks suggest that our method can reconstruct the end‐to‐end network traffic more accurately than previous methods. Copyright © 2013 John Wiley & Sons, Ltd.     

S2‐Net: Machine reading comprehension with SRU‐based self‐matching networks

Machine reading comprehension is the task of understanding a given context and finding the correct response in that context. A simple recurrent unit (SRU) is a model that solves the vanishing gradient problem in a recurrent neural network (RNN) using a neural gate, such as a gated recurrent unit (GRU) and long short‐term memory (LSTM); moreover, it removes the previous hidden state from the input gate to improve the speed compared to GRU and LSTM. A self‐matching network, used in R‐Net, can have a similar effect to coreference resolution because the self‐matching network can obtain context information of a similar meaning by calculating the attention weight for its own RNN sequence. In this paper, we construct a dataset for Korean machine reading comprehension and propose an S²‐Net model that adds a self‐matching layer to an encoder RNN using multilayer SRU. The experimental results show that the proposed S²‐Net model has performance of single 68.82% EM and 81.25% F1, and ensemble 70.81% EM, 82.48% F1 in the Korean machine reading comprehension test dataset, and has single 71.30% EM and 80.37% F1 and ensemble 73.29% EM and 81.54% F1 performance in the SQuAD dev dataset.     

P2P网络管理系统信息模型的设计与实现

为满足基于P2P的网络管理体系结构中管理节点间的协作需求,提出了一种基于语义Web服务和XML的网络管理信息模型.利用P2P通信和语义Web服务,可实现网管服务的分布式注册,服务的统一描述和基于能力的服务检索;利用XML来制订网络管理服务调用的标准,可以实现服务的跨域自动调用.原型实现和运行测试表明,利用提出的模型框架,异构网络管理系统可以通过节点间的服务调用和信息共享实现管理任务的协作.     

Network coding based on hyper‐edge decomposition for wireless network with link failures

This paper is concerned with the construction of network coding for wireless network with link failures. Based on hyper‐edge decomposition, for the wireless network, we first construct the hyper‐edge graph, where each node represents one hyper‐edge (consisting of multiple adjacent edges transmitting the same information) of the wireless network. Then we present a heuristic coloration method for the hyper‐edge graph, and a network coding vector allocation scheme based on maximum distance separable code is proposed to effectively overcome some link failures. Copyright © 2014 John Wiley & Sons, Ltd.     

基于Gnutella协议的P2P网络中DoS攻击防御机制

对基于Gnutella协议的P2P计算网络实施DoS攻击的特征进行了详细分析,通过设置攻击容忍度和防御起点,提出了一种简单的基于特征的DoS攻击防御策略,运用基于贝叶斯推理的异常检测方法发现攻击,使系统能根据DoS攻击的强弱,自适应调整防御机制,维持网络的服务性能.仿真结果表明,本文提出的防御策略能有效的防御恶意节点对网络发动的DoS攻击,使网络服务的有效性达到98%,正常请求包被丢弃的平均概率为1.83%,预防机制平均时间开销仅占网络总开销的6.5%.     

A compressive sensing‐based network tomography approach to estimating origin–destination flow traffic in large‐scale backbone networks

A traffic matrix can exhibit the volume of network traffic from origin nodes to destination nodes. It is a critical input parameter to network management and traffic engineering, and thus it is necessary to obtain accurate traffic matrix estimates. Network tomography method is widely used to reconstruct end‐to‐end network traffic from link loads and routing matrix in a large‐scale Internet protocol backbone networks. However, it is a significant challenge because solving network tomography model is an ill‐posed and under‐constrained inverse problem. Compressive sensing reconstruction algorithms have been well known as efficient and precise approaches to deal with the under‐constrained inference problem. Hence, in this paper, we propose a compressive sensing‐based network traffic reconstruction algorithm. Taking into account the constraints in compressive sensing theory, we propose an approach for constructing a novel network tomography model that obeys the constraints of compressive sensing. In the proposed network tomography model, a framework of measurement matrix according to routing matrix is proposed. To obtain optimal traffic matrix estimates, we propose an iteration algorithm to solve the proposed model. Numerical results demonstrate that our method is able to pursuit the trace of each origin–destination flow faithfully. Copyright © 2014 John Wiley & Sons, Ltd.     

Performance analysis of a P2P‐enabled TDD‐CDMA network with intra‐cell spatial resource reuse

In this paper a scheme of intra‐cell spatial resource reuse is proposed for a peer‐to‐peer (P2P) enabled TDD‐CDMA system to increase the system capacity via only software update. On account of the new interference scenario in our scheme, a more accurate model of signal to interference and noise ratio (SINR) is deduced and analyzed instead of using the conventional equation. As demonstrated by our system‐level simulations, the capacity is significantly improved by reusing the same radio resource among different P2P transmitters within a single cellular cell in the spatial domain. Furthermore, we employ critical values of SINR target observed from simulation results to indicate whether the P2P‐enabled system is resource‐restricted or interference‐restricted for a certain application scenario. By means of a hexagon‐padding plan, the relation between co‐channel reuse distance and single‐hop distance is also pointed out to help to apply our scheme to a real implementation. Copyright © 2008 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.     

Mitigating file‐sharing misbehavior with movement synchronization to increase end‐to‐end availability for delay sensitive streams in vehicular P2P devices

When dealing with wireless connectivity in a mobile peer‐to‐peer (MP2P) environment, there are many concerns about the offered efficiency and availability of the requested resources and concerns about practicality considerations. These considerations deal with the movement and deployment of continuous connectivity. The intermittent connectivity is a major factor for object sharing misbehavior because it aggravates the connectivity and reliability. MP2P environments are in need of specialized placement algorithms where structured index‐centric solutions will be able to provide efficiency and object location determination over intermittent connectivity and communication. Replication of any requested object and redundancy face the requests' failures because they create severe duplications, and aggravate the capacity of the end‐to‐end path. This work proposes a framework that enables mitigation between the file sharing misbehavior in contrast to the movement synchronization, and it quantifies the parameters that affect the end‐to‐end efficient transmission by taking into consideration the synchronization between moving peers to assign the requested resources in the end‐to‐end path. Resilience metrics are introduced to enable reliability in cooperative file sharing procedure. The proposed scheme considers synchronization and assignment of the moving mobile Infostation peer with certain object indices to a certain vehicle via a synchronized cooperative scheme where the file sharing process is performed through the message ferry mobile peer. In addition, a resource assignment cooperation engine is developed taking into consideration the social cooperation model and the end‐to‐end capacity of the relay path. The proposed resource exchange apparatus for file chunks' migration is performed to enable delay sensitive streaming. The proposed model is evaluated through experimental simulation taking measures for the throughput and the reliability offered and for the robustness for sharing resources of any capacity in dynamically changing MP2P wireless environments under synchronized movements. Copyright © 2012 John Wiley & Sons, Ltd.