A Comparison of Link Layer Attacks on Wireless Sensor Networks

Wireless sensor networks (WSNs) have many potential applications [1,2] and unique challenges. They usually consist of hundreds or thousands of small sensor nodes such as MICA2, which operate autonomously;conditions such as cost, invisible deployment and many application domains, lead to small size and resource limited sensors [3]. WSNs are susceptible to many types of link layer attacks [1] and most of traditional network security techniques are unusable on WSNs [3];This is due to wireless and shared nature of communication channel, untrusted transmissions, deployment in open environments, unattended nature and limited resources [1]. Therefore security is a vital requirement for these networks;but we have to design a proper security mechanism that attends to WSN’s constraints and requirements. In this paper, we focus on security of WSNs, divide it (the WSNs security) into four categories and will consider them, include: an overview of WSNs, security in WSNs, the threat model on WSNs, a wide variety of WSNs’ link layer attacks and a comparison of them. This work enables us to identify the purpose and capabilities of the attackers;furthermore, the goal and effects of the link layer attacks on WSNs are introduced. Also, this paper discusses known approaches of security detection and defensive mechanisms against the link layer attacks;this would enable IT security managers to manage the link layer attacks of WSNs more effectively.

Bluetooth Low Energy Device Identification Based on Link Layer Broadcast Packet Fingerprinting

With the rapid development of the Internet of Things(IoT),wireless technology has become an indispensable part of modern computing platforms and embedded systems.Wireless device fingerprint identification is deemed as a promising solution towards enhancing the security of device access authentication and communication process in the IoT scenario.However,the extraction of features from the network layer and its upper layers often confront restrictions from specific devices:the association with a certain wireless network and the access to the plaintext of the payload.Meanwhile,Bluetooth Low Energy(BLE)packets have been encrypted above the link layer,which makes those features difficult to extract.To tackle these problems,we introduce a novel method to identify BLE devices based on the fingerprint features in the data link layer.Initially,the BLE packets are collected through a receiver based on software-defined radio technology.Then,fields that reflect device differences in BLE broadcast packets are extracted through traffic analysis.Finally,a MultiLayer Perceptron(MLP)model is employed to recognize the category of BLE devices.An experimental result on a dataset with 15 types of BLE devices shows that the identification accuracy of the proposed method can reach 99.8%,which accomplishes better performance over previous work.

面向Link16的QualNet与虚拟机信息交互接口设计与实现

Link16是美国国防部采用的高速视距战术数据链,广泛应用于美国海军、联合部队和北约部队,针对其开展测试评估具有重要军事意义。通过硬件在环技术将Link16实物设备接入到仿真测试中,可有效提高测试结果的真实性和准确性。然而当测试场景需要进行实物设备组网测试时,仍会带来成本问题。为此,提出一种面向QualNet MAC层的Link16专属模型以及与之匹配的虚拟机信息交互接口。该模型可高逼真模拟Link16通信行为,实现Link16节点竞争接入、时隙划分、NPG分组等功能。并基于数据分布式服务实现了虚拟机交互接口,将运行在虚拟机的Link16设备模型接入QualNet测试场景。实验测试结果表明,所设计模型具有较高真实性和准确性且接口引入延时不超过1 ms,为大规模数据链网络测试提供一种新方法。

Analysis on Connectivity of Inter-Orbit-Links in a MEO/LEO Double-Layer Satellite Network

As an important scheme of future global mobile satellite communication systems to provide multimedia service, a Double-Layer Satellite Network （DLSN） with MEO satellites and LEO satellites is proposed. The Inter-Orbit-Links （IOLs） between layers is an essential factor, which affects the performances of the DLSN systems. Considering certain constellation parameters, the geometric characteristics of IOLs are described and the connectivity of MEO satellites and LEO satellites in the DLSN is analyzed. By computer simulation, the results show that IOLs should be selectively established according to certain parameters rather than the simple in-sight principle.

Electron Communication Between Electrode and Dye-Linked L-Proline Dehydrogenase in Organized Layer-by-Layer Multilayer Film

Multilayer film was fabricated on an electrode surface by alternate layer-by-layer（LBL） adsorption of polycationic redox polymer（PEI-Fc） and dye-linked L-proline dehydrogenase（L-proDH）.The electrochemistry of the PEI-Fc/L-proDH multilayer modified electrode was investigated by cyclic voltammetry,and the enzyme catalysis mediated by the redox polymer was studied in a solution containing L-proline.It was observed that electron communication between L-proDH and the electrode was achieved with the help of PEI-Fc.A mathematical expression for the current response was evaluated based on the Michaelis-Menten kinetics mode,and the calculated currents fitted well with the experimental data.The kinetic analysis indicates that only a small fraction of the immobilized enzyme was efficiently electrically wired by the redox polymer.

Link-16数据链分层模型分析

针对多种数据链之间标准不统一、交互困难的问题,在开放式系统互联(OSI)模型的基础上,提出一种数据链的通用模型。分析Link-16数据链的消息标准、时隙分配方式和通信协议,使用通用模型对Link-16数据链进行建模;通过研究Link-16数据链工作过程中的入网技术、同步技术、时隙接入技术和网络成员之间微小时间差的捕获技术,给出Link-16数据链端机的同步原理和入网方法;结合Link-16数据链的具体相关参数,给出通用模型的物理层和链路层的具体实现方法。

受干扰的Link-16链路层仿真分析

从Link-16信号的实际传输和处理过程的角度出发,介绍了该信号的特征、参数和处理模型,通过Simulink软件对受到干扰的Link-16链路层进行了仿真,该链路层的仿真模型包括信源模块、干扰模块、信道模块、信宿模块和质量评估模块。仿真结果表明,随着干扰功率和干扰距离的渐变,误码率会发生跃变,发生跃变时的干扰功率为最低有效干扰功率,也就是最佳有效干扰功率,功率过小不能形成有效干扰,而功率过大只会造成浪费。

浅谈DLSW（DatalinkswitchingPlus）在网络配置中的应用

本文描述DLSw＋及．其设计和配置DLSw＋网络。标准的DLSW关键特性和在DLSw＋中增强特性。通过了解DLSW的基本原理及其配置方法可以简化网管人员的工作步骤，提高工作效率。

Improved AODV Routing Protocol Based on Link Stability and Channel Switching

Ad hoc on-demand distance vector( AODV) routing is one of the typical reactive routing protocols of vehicular ad hoc networks( VANET). Considering link stability and channel switching can greatly improve the QoS of protocols,in this paper,we propose a novel routing protocol: optimized cross-layer AODV( CL_ AODV) designed for VANET. It utilizes the frame transmission efficiency( FTE),path bandwidth in media access control( MAC) layer and signal-to-noise ratio( SNIR) in physical( PHY) layer to improve the link stability. In other words,it can increase packet delivery ratio effectively. In addition,end-to-end delay will be decreased based on the channel switching. According to the simulation,it is shown that the packet delivery ratio of CL_AODV is almost up to 99% and the highest compared to AODV and muti-constrained QoS AODV( MQ_ AODV). The delay of CL_AODV is almost half of MQ_ AODV's and 1 /3 of AODV's.Meanwhile,CL_AODV has the highest routing overhead or energy consuming. Because of the feature of VANET,the disadvantage can be ignored.

Investigation on Avian Leukosis Virus Subgroup A in Layers in Guizhou Province of China

A total of 273 serum samples were collected from 10 layer breeding farms in Guizhou Province and detected by enzyme-linked immunosorbent assay. The positive rate of antibodies against avian leukosis virus reached 14.64%. Then the samples from cases of hemangioma in one of the 10 breeding farms were detected by polymerase chain reaction, and the diagnosis indicated that the hemangioma was caused by avian leukosis virus subgroup A.

Pt Deposition on Anode Enhances the Performance of Dye-Sensitized Solar Cell with Non-Cross-Linked Gel Electrolyte

We fabricated dye-sensitized solar cells with non-cross-linked fluorinated gel electrolyte. The application of fluorinated gel to electrolyte is a challenging issue at present. The gelation of the electrolyte is of importance in order to solve the problem in the durability of the cell. We investigated, in this article, the effect of Pt deposition on the anode of the cell. The Pt was deposited by means of a DC sputtering technique. The studies showed that the deposition time strongly affected both open voltage and short-circuit current of the cell. The adaptive thickness of the Pt layer was determined to be 10 nm for the non-cross-linked fluorinated gel electrolyte cells.

Link-16模型与抗干扰性能分析

在介绍Link-16的帧结构和物理层技术的基础上,给出了Link-16发送端模型,对各个模块进行了详细的说明,并对其进行了MATLAB仿真分析。其后对Link-16在对抗跟踪式干扰、部分频带干扰以及宽带压制干扰时的抗干扰性能进行了分析。

Synchronizability of Two-Layer Cluster Ring Networks

Multilayer network is a frontier direction of network science research. In this paper, the cluster ring network is extended to a two-layer network model, and the inner structures of the cluster blocks are random, small world or scale-free. We study the influence of network scale, the interlayer linking weight and interlayer linking fraction on synchronizability. It is found that the synchronizability of the two-layer cluster ring network decreases with the increase of network size. There is an optimum value of the interlayer linking weight in the two-layer cluster ring network, which makes the synchronizability of the network reach the optimum. When the interlayer linking weight and the interlayer linking fraction are very small, the change of them will affect the synchronizability.

阿尔茨海默病的多层脑网络链路预测重构

功能脑网络的构建工作是阿尔茨海默病辅助诊断中的基础任务.针对基于全频域的单层网络构建方法难以处理小频段间的异质性特征以及脑网络中可能存在错误边或缺失边的问题,提出一种基于多层网络链路预测的功能脑网络模型.利用多层网络框架使节点间存在多个频段描述下的连接关系,并设计融合层间相似性和节点重要性的局部相似性指标,进而基于多层网络拓扑结构进行链路预测,以重构网络结构.实验结果表明,与当前先进的脑网络模型相比,该模型在阿尔茨海默病分类诊断中性能表现更好,证明所提模型能有效提升网络表达的精准性,且在计算机辅助诊断中具有良好的应用价值.

煤沥青交联改性处理对碳结构的影响

沥青基炭制品的碳结构高度依赖前驱体沥青的性质。采用化学交联的方法对沥青进行改性处理时,尽管化学交联的反应机理为亲电取代反应,但交联剂、催化剂的种类不同,沥青改性程度存在差异,进而影响炭制品结构。以中低温煤沥青为原料,探索3种交联剂(对苯二甲醇(PXG)、苯甲醛(BA)、对苯二甲酰氯(TPC))、5种催化剂(对甲苯磺酸、浓硫酸、浓硝酸、浓盐酸、硼酸)对沥青交联改性后炭制品结构的影响。通过TG-DTG、FT-IR研究交联改性后沥青热稳定性及沥青官能团的变化;借助XRD、Raman表征改性后沥青炭制品的微观结构差异。结果表明:交联剂和催化剂的存在促进了沥青分子的交联,有效阻止了热转化过程中轻组分挥发,提高了沥青的结焦值、软化点、热稳定等指标。以PXG为交联剂,沥青支链上亚甲基CH_(2)的H不易被取代;而以硼酸为催化剂时,支链末端甲基上的H易被取代;以BA为交联剂,取代氢的位置明显发生在芳香环上;以TPC为交联剂、浓硫酸为催化剂时,交联产品的C=0官能团含量增加,说明在这种组合下,TPC参加反应较多。无论与哪种交联剂相结合,浓盐酸为催化剂时,交联反应更易促进苯环上和支链上的C—H键发生取代反应。经过交联改性后的沥青,炭化过程中分子间较强的π-π相互作用减弱,有效阻止碳有序结构的形成,碳无序结构含量I_(D)/I_(G)增大。同时碳微晶层间距d_(002)明显增加,有序堆积平均堆积高度L_(c)减小,芳香层数降低,说明化学交联不仅影响有序碳结构排列,还可抑制碳微晶结构发育。其中硼酸作为催化剂时,催化效果更理想。获得的炭制品d_(002)在同组产品中最大。PXG、硼酸组合与沥青发生交联时,所得碳材料的d_(002)达0.377 nm。本研究为进一步定向调控和构筑沥青基碳材料奠定基础。

面向6G通信的多层低轨卫星网络路由算法

在面向6G的移动通信网络中,低轨卫星网络(LEO,Low Earth Orbit)运行高度低、时延小,可大范围部署实现全球广域低时延通信。当前低轨卫星星座正朝着多层轨道面发展,多层轨道的跨层链路增加了数据传输路径,但跨层轨间链路的频繁通断,增大了多层LEO网络层间路由选择的难度。为此提出了一种面向6G移动通信的多层LEO卫星网络路由算法。首先建立跨层链路,面向端到端传输时延和可靠性需求,分析影响跨层轨间链路频繁通断的因素,基于LEO卫星网络虚拟位置思想,选择卫星节点对建立可靠跨层链路;然后实现路由选择,基于所建立的跨层星间链路,采用时空演化图模型刻画动态网络拓扑,设计最短路径算法计算最佳传输路径。最后,构建三层卫星网络场景对所提算法进行仿真验证。结果表明,相对于现有方法,所提算法在端到端时延和可靠性均有明显提升。

融合Inception与SE-Attention的加密流量移动业务识别

移动设备通常接入无线局域网,并依赖WiFi加密协议对网络中数据链路层流量进行加密,以维护通信安全。然而,现有加密流量识别方法主要针对网络层及以上的流量载荷进行分析,无法有效识别链路层加密流量的移动业务类别。针对该问题,提出了一种在WiFi加密场景下基于链路层流量的移动业务识别方法。通过被动嗅探WiFi数据帧,提取链路层中可用的流量侧信道特征,将流量数据转换为二维直方图矩阵。融合Inception网络和SE-Attention机制,提出识别模型——SE-Inception,旨在更好地捕捉到流量数据帧分布特征中的细节和全局信息,突出对重要特征的关注,以提高识别准确率。文中采用真实数据集进行实验验证,结果表明该方法在WiFi加密场景下可有效识别链路层加密流量的移动业务类别,平均准确率可达98.29%,相比于已有的识别方法具有更优的性能。

舰船网络通信接口数据传输功耗预测模型

针对舰船网络环境复杂,通信接口数据传输功耗预测精度过低的问题,设计舰船网络通信接口数据传输功耗预测模型。由传输层、网络层、数据链路层等组成舰船网络通信数据传输模型,舰船网络通信接口位于数据链路层作为光导纤维媒介,进行舰船网络的数据传输。舰船网络通信接口数据传输的总功耗,由动态功耗、空闲功耗以及泄露功耗组成。利用指数平均预测算法,引入微分调节因子,构建数据传输功耗预测模型。利用权重系数衡量通信接口功耗预测真实值与预测值的偏离程度,实现舰船网络通信接口功耗的精准预测。模型测试结果表明,该模型能够有效预测舰船网络通信接口数据传输功耗,数据传输功耗预测的均方误差低于0.04。

面向卫星互联网的链路层加密系统设计

全球卫星通信行业进入卫星互联网发展阶段,面对复杂多变的国际政治格局环境及日益严峻的网络攻击挑战,卫星互联网安全至关重要。针对上述问题创新性地构建了卫星互联网网络模型,分析卫星互联网海量用户、空间开放、网络互联、网络拓扑高动态等特点带来的卫星互联网空间链路安全风险。基于“适度防护、应密尽密”的原则,设计一套卫星互联网链路层加密系统,该系统架构灵活适配卫星互联网网络架构、运营模式、应用场景特征等。特别是面向卫星互联网海量用户不同需求,优化加密通信协议;针对卫星互联网网络节点多、高动态的特点重点对链路层加密系统密钥管理功能进行设计,保障卫星互联网业务全流程应用过程中的业务数据和关键管理信息安全传输,显著提升卫星互联网空间链路的安全防护水平。基于中星26号卫星实测验证本系统在全业务流程、不同数据类型的加密能力,结果表明本加密系统可对业务数据和关键信息加密。

移动PI-HMIPv6快速切换技术及仿真分析

本文主要探究了移动PI-HMIPv6快速切换技术的基本原理和运行流程。采用对照试验方法,使用网络仿真器NS-2软件搭建仿真环境,设定好仿真参数后,对比了MIPv6、HMIPv6和PI-HMIPv6三种协议下移动节点的切换时延。仿真结果表明,移动节点无论是在域内切换还是在域间切换,PI-HMIPv6的切换时延均维持在300~500 ms之间,明显低于MIPv6和HMIPv6。由此可得,移动PI-HMIPv6快速切换技术能够将切换时延维持在较低水平,满足了通信业务的实时性要求。