共查询到20条相似文献,搜索用时 31 毫秒
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单纯用TCP或UDP实现局域网通信存在很多不足,为了建立高效、稳定、可靠的通信。并以多媒体教学系统的软件开发为例,在Delphi平台上,运用Indy9.0组件,将UDP和TCP结合起来,实现了局域网中C/S模式的通信。首先简述TCP,UDP协议的特点,对网络中三种基本的数据传输模式进行了比较,然后介绍Indy技术,最后写出实现这种方式的关键步骤和程序。 相似文献
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TCP and UDP are considered the most popular and well known transport layer protocols to facilitate the end to end communication between two nodes in the network. TCP is used as the transport layer protocol in packet delivery and error sensitive applications, where packet loss cannot be compromised. However, low-rate TCP targeted Denial of Service (DoS) attacks exploit the retransmission timeout and congestion control features of TCP protocol. These low-rate TCP targeted Denial of Service (DoS) attacks are also called JellyFish (JF) attacks. These attacks perform the malicious activities either by delaying, or periodically dropping or mis-ordering the data packets on the route from source to destination node in the network, and cause severe degradation in end-to-end throughput in the network. JellyFish attack is further classified as JF-Delay Variance Attack, JF-Periodic Drop Attack and JF-Reorder Attack based on the type of the malicious activities being performed. JellyFish attack conforms to all existing routing and packet forwarding protocol specifications, and therefore it becomes very difficult to detect its presence in the network. In this paper, a Friendship Based JellyFish Attack Detection Algorithm (FJADA) is presented for Mobile Ad Hoc Networks, where the basic concept of friendship mechanism is added to the existing Direct Trust-based Detection (DTD) algorithm to save the valuable resources of a node in monitoring the activities of its one hop neighbours, through promiscuous mode. FJADA also minimizes the possibility of overestimating the malicious behaviour of innocent nodes due to radio transmission errors, network congestion or packet collisions. The results obtained throughout the simulation experiments clearly show the feasibility and effectiveness of the proposed detection algorithm. 相似文献
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基于端信息自适应跳变的主动网络防御模型 总被引:1,自引:0,他引:1
端信息跳变是目前主动网络防御领域的研究热点之一。该文构建了固定策略下的定时隙端信息跳变模型,分析了固定跳变周期引起的防御收益下降和跳变边界数据包丢失造成的服务损失问题。提出了基于非广延熵和Sibson熵融合的实时网络异常度量算法,在此基础上设计了端信息跳变周期和跳变空间自调整策略,构建了主动网络防御模型,提高了防御收益。给出了基于网络时延预测的跳变周期拉伸策略,保证了跳变边界的服务质量。理论分析与仿真实验结果表明了所提模型在网络防御中的有效性和良好的服务性。 相似文献
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Inspired by the spread spectrum technology for communications,the concept of end spreading was proposed to represent a piece of information of the data transmission with a sequence of multiple end information,of which each piece of end information was irrelevant to the information it conveys.Thus the covert data transmission can be performed.Further,an active cyber defense model of end information hopping and spreading was presented,in which the hopping strategy was separated from the synchronization strategy.The synchronization was accomplished by means of end information spreading for synchronous authentication of both parties,which can solve the high-speed hopping synchronization problem with high concealment requirements.The mode of generation,transmission and authentication of the spreading sequence,and the data migration strategy in the end hopping and spreading model were described in detail,and the security performance and synchronization performance were analyzed and verified experimentally.Theoretical analysis and experimental results show that the cyber defense model of end information hopping and spreading has improved the availability and confidentiality of network services under high-speed hopping and has good anti-attack performance,which is of great significance for the proactive defense application of high intensity confrontation. 相似文献
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随着计算机技术,网络技术,通信技术的迅速发展,越来越多的网络信息走入了大众的生活,对网络信息的传输设计和实现技术要求也越来越高。论文研究基于VC的UDP网络编程的设计与实现,并采用异步传输技术实现了一个简单的UDP Server。 相似文献
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IP多播是一类重要的基于IP的应用,支持很多业务。无线接入系统使用灵活,作为IP网络的最后一跳,对组网寻址、服务质量构成影响;鉴于无线接入系统存在带宽有限、传输质量逊于有线方式等不足,所以在寻址方面通过合理的无线链路多播机制与IP多播寻址进行映射,在传输质量方面,通过对有线分组进行分片、ARQ、流控等机制,弥补UDP协议无流控、无确认等缺陷,以期提高服务质量。 相似文献
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IP 网络通过连接全球大量的网络设备给人类带来了便利,但网络面临持续性的安全和隐私问题令人担忧。由于网络缺乏内生安全的设计,IP地址伪造、隐私泄露、中间人攻击、分布式拒绝服务(DDoS)攻击等顽固安全问题难以根治,传统的补丁式解决方案补不胜补。在研究IP网络面临的各类安全威胁及相关安全技术的基础上,剖析了IP网络固有的安全缺陷,提出了具有内生安全特性的网络架构,包括具有内生安全的隐私ID/Loc、安全验证和审计协议、跨域联合防御机制等,能够为端到端通信保驾护航。 相似文献
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Design of next generation high throughput satellite communication system based on beam-hopping 总被引:1,自引:0,他引:1
Beam-hopping technology provides a basis for flexible allocation and efficient utilization of satellite resources,and it is considered as a key technology of the new generation of high-throughput satellite.With the goal of service-driven,efficient utilization of resources and on-demand coverage of hot spots area,from the aspects of system architecture,communication system,working mechanism,resource allocation method and beam-hopping pattern design,user access strategy,air interface protocol design and system workflow,a top-down feasibility and technical foundation was provided for the design of a new generation of high-throughput satellite communication system based on beam hopping.Finally,it meet the requirements of flexible and mobile information service for the space-earth integration network,as well as the demand of the space-based backbone network with high reliability and large capacity transmission. 相似文献
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为提高UDP网络通信的可靠性,设计了一个基于STM32F429和W5500的嵌入式双网冗余UDP通信模块,硬件上设计了相互热备份双网冗余电路,软件上采用了时间片轮询方法,通过读取W5500状态数据发现网络故障,并设计了快速可靠的切换策略,实现了两路网络的切换,切换时间小于10ms,该设备在实际应用过程中,工作稳定可靠。 相似文献
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差分跳频通信中的关键技术分析 总被引:1,自引:0,他引:1
介绍了近年来扩频通信的一种全新通信体制——差分跳频通信的原理,阐述了其与普通跳频通信的区别,重点分析了差分跳频通信所需解决的两个关键技术:G函数设计和接收信号检测技术。最后指出了差分跳频通信的应用前景和发展方向。 相似文献
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《中国邮电高校学报(英文版)》2014
Network address hopping (NAH) proposed a mechanism to enhance data protection in communications across untrusted networks. It spread the data stream of a communication session across multiple channels, which tried to obstruct information interception in the first place by obscuring the fact that communication takes place between certain end-points. However, the time-stamped packets between two peers would provide a hint for correlating the intercepted packets in case the encryption of the counter got compromised. Furthermore, due to synchronization, the Internet Protocol version 6 (IPv6) addresses pair of the channel ends would appear and disappear strictly, which would perform time-relevance character. A Network-based hopping communication mechanism (NetHop) is proposed in this paper. The address hopping function is deployed on the network side instead of endpoint, which can support secure hopping communication function for universal endpoints without any restriction of Operating System or hardware. By using IPv6 to IPv6 network address translation (NAT), NetHop fully exploits the superiority of IPv6 huge address space. The hopping addresses are generated by hash function and the hopping addresses pair can be chosen randomly. Consequently, NetHop performs better on randomness and concealment than channel-rule NAH. 相似文献