探究解决局域网内DHCP冲突问题

随着计算机科学技术的快速发展,计算机通信网络和Internet已经成为工作、生活和学习必不可少的组成部分。在局域网管理中,网络管理员普遍使用DHCP进行网络配置,确保能够安全、可靠、方便地进行动态IP地址分配。然而如果在同一个局域网中,由于各种原因存在多个非法的DHCP服务时,会造成DHCP服务冲突,从而发生了计算机获取不了正确的IP地址,无法正确上网的问题。为了解决上述问题,该人通过使用Cisco Packet Tracer软件来模拟DHCP产生冲突的现象,通过技术分析探究产生DHCP冲突的原因,进而提出解决DHCP冲突的解决方法。     

一种对IP地址分配的监测管理方法和实现

采用DHCP服务器自动分配IP地址,是解决IP地址不足的有效途径.但是,即使在采用DHCP的环境中,IP地址冲突的情形仍偶有发生,因为用户仍可手动设定自己计算机的IP地址,不理会DHCP所分配的网段,这种情况在校园网络屡见不鲜.文章提出一种IP地址指派的监测机制,通过SNMP网络管理协议至路由器设备检查网络中IP地址的使用情形,并通过DHCP日志文件的分析,找出违反规定使用IP地址的计算机,解决IP地址盗用与地址冲突的问题,可以有效降低网管人员的负担.     

基于DHCP Snooping的校园网ARP防范研究

针对校园网普遍存在的ARP攻击、私设DHCP服务器和IP地址冲突等问题,经过分析ARP攻击原理,并结合本院实例给出了基于DHCP Snooping的校园网ARP防范解决方案。     

IP地址冲突怎么办？如何解决IP地址冲突？

在同一个局域网里如果有两个用户同时使用了相同的IP地址,或者一个用户已经通过DHCP得到了一个IP地址。而此时又有其他用户以手工分配方式设定了与此相同的IP地址,这将造成IP地址冲突,并会令其中一个用户无法正常使用网络。     

基于DHCP Snooping的校园网ARP防范研究

针对校园网普遍存在的ARP攻击、私设DHCP服务器和IP地址冲突等问题,经过分析ARP攻击原理,并结合本院实例给出了基于DHCP Snooping的校园网ARP防范解决方案。     

DDoS攻击的检测与溯源探析

分布式拒绝服务攻击是当前流行的网络攻击手段之一,影响力巨大。本文主要探讨了DDoS攻击的检测方法和IP溯源技术,重点分析3种DDoS检测方法:流量、日志、数据包分析法,提出了运用数据包切片标记实现对伪造IP攻击溯源的方法。通过搭建分布式DDoS攻击实验环境,综合应用流量监控、日志分析和数据包切片标记的方法实现了对DDoS的IP溯源。通过反复实验测试,证明方法的可行性、准确率可达90%。     

基于IP DHCP Snooping的大型局域网安全策略研究

本文针对公司内部局域网存在的IP地址冲突和ARP攻击这两大类问题。在对问题的发生原因进行深入的挖掘和分析之后,提出使用IP DHCP Snooping、DAI（Dynamic ARP Inspection）和IPSG（IP Source Guard）技术。对局域网管理进行优化,从根本上解决了这两大问题。     

DHCP客户端在ARM下的设计与实现

为了解决嵌入式设备无法自动获取或释放IP的问题,针对ARM9（S3C2440）嵌入式开发板,在Fedora操作系统上,配置了交叉编译环境,编写了动态主机配置协议（DHCP）客户端程序代码。利用交叉编译环境对其进行编译,将编译成功产生的程序移植到以ARM9开发板为核心的嵌入式操作系统上。测试结果表明,该软件可以在ARM9处理器的Linux和Android嵌入式操作系统上运行,在嵌入式设备开机时,软件自动运行,广播发送报文寻找DHCP服务器,自动获取IP后,动态配置嵌入式设备的IP及各项网络参数。     

基于Wireshark的DHCP协议工作流程研究

DHCP是用于动态分配IP地址的网络协议,Wireshark是截取和分析网络数据包的工具软件.为研究学习DHCP协议的工作流程,并为后续的网络攻防研究打下基础,设计了一个实验.在虚拟机环境下模拟了DHCP服务器为客户端动态分配IP的过程,并通过Wireshark对DCHP数据包进行截取与分析.     

无法登录宽带猫管理页面

Q使用宽带猫(Modem)连接到路由器,输入192.168.1.1后打开的总是路由器的管理页面,无法登录到宽带猫的管理页面。请问如何才能同时登录到这两个设备的管理页面?A可以分别连接这两个设备,之后将猫和路由器设置为同一网段但是不同的IP,例如路由器是192.168.1.1,猫是192.168.1.2。注意,路由器的DHCP不要和猫的IP冲突(只在猫或者路由器上启用DHCP)。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate