数据包的拦截与过滤研究与实现

数据包的拦截与过滤广泛应用于信息安全产品的研发中,如防火墙、入侵检测系统、病毒防范等。本文介绍了NDIS驱动程序结构,给出NDIS中间驱动程序实现网络数据包的拦截方法;并实现了一个基于规则的过滤算法,在过滤算法中引入了一个分层框架。     

IPv6下DoS/DDoS SYN Flood入侵和攻击的检测

在网络安全状况划分的前提下,分析SYN Flood半连接攻击的形式和特点.为了防范这种使网络资源耗尽的攻击,提出Ipv6下跟踪三次握手的SYN Flood入侵和攻击的检测方法,对系统实现的数据结构进行设计与论证.最后在"一个广播的局域网"的问题规模下对该系统的有效性进行测试.结果表明,模拟检测系统能够将含错误数据的数据包丢弃,将分片的数据包重新组合成完整的数据包.     

基于NDIS-HOOK与SPI的个人防火墙设计

当前个人网络安全产品中,个人防火墙是一个非常重要的网络安全产品。利用NDIS-HOOK与SPI相结合在Windows下设计了一个基于NDIS-HOOK与SPI的个人防火墙。其中,在应用层利用SPI进行封包来过滤各种应用程序,而在核心层利用NDIS-HOOK来过滤各种非Socket通信的数据包,实现底层的数据包的捕获,从而能更好地过滤数据。     

包过滤系统中关键字过滤的实现及其性能分析

一般的包过滤系统仅对IP(Internet Protocol)地址、端口类型等项目进行过滤。笔者提出了对数据包中的数据按照关键字进行过滤的方法，并基于KMP(Kunth—Morris—Pratt)关键字匹配算法，对该系统进行了相应的性能测试。在测试环境下，得出网络吞吐量为75％，1000字节长的数据帧的平均过滤时延约为100μs等一系列测试数据。通过对过滤时延的分析及网络吞吐量的调试结果表明，该方案所设计的系统性能基本能够满足实际要求。     

基于高速网络环境的Snort主动包过滤预处理器研究

提出一种Snort主动包过滤预处理插件,在高速网络环境下,通过主动丢弃对检测误报率影响较小的数据包减轻系统负载,避免Snort在超负荷运行情况下的随机丢包现象。由于异常数据包主要来自于每个网络流前面的一定数量的数据包。因此,该预处理器实时地监控Snort的负载变化,当检测引擎负载超过一定阈值时,主动过滤掉网络流后面的正常数据包。实验表明,使用主动包过滤预处理器并采用一定的Snort调整行为可以在保证较低误报率的前提下有效降低Snort的漏报率,提高系统的检测效率。     

一种高效的安全数据包过滤算法

基于网络编码技术,通过计算收到的数据包的线性相关性来判断其是否为非创新包,并检测它们是否为污染包,以阻止恶意节点的攻击行为,提出一个抗熵攻击和污染攻击的数据包过滤算法.分析和实验结果表明,给出的数据包过滤算法安全,并且能有效减少网络负载、提高传输效率.     

利用VC++编程实现防火墙数据包过滤

随着计算机网络深入社会、经济、国防、科技与文教等各个领域 ,计算机系统的安全问题正变得日益复杂和突出 .资源共享和网络分部更增加了网络收到威胁和攻击的可能性 ,于是基于包过滤加状态检测的防火墙系统成为保护网络安全的工具 .文中介绍一种集数据包过滤、日志、代理服务于一体的复合型防火墙系统 ,着重论述利用 VC 编程技术实现数据包过滤的软件方法 .     

Ipv4与Ipv6转换技术的研究

随着Internet网络在全球范围内的迅速扩大,应用日益增加,IP地址即将耗尽的矛盾更加突出,同时为解决Ipv4的设计缺陷,国际互联网工程任务组开发了新一代Internet协议Ipv6,但由于Ipv4与Ipv6之间存在着很大的差异,同时存在众多基于Ipv4协议的网络及应用,因此,要用新的Ipv6代替旧的Ipv4必然存在一个过渡时期。针对上述问题我们对Ipv4和IPv6的转换技术进形象了分析和研究。     

Linux内核Netfilter包过滤防火墙的设计与实现

讨论并分析了Netfilter的功能框架、工作原理及数据包过滤的实现机制,研究了在Netfilter框架中如何扩展用户自定义的可装载内核模块,开发并实现了IPv4协议下基于IP和端口的数据包过滤防火墙功能.深入学习和研究Netfilter框架及其可扩展性,该研究也为构建特定用户安全需求的防火墙系统提供借鉴.     

基于Linux系统实现透明网桥式安全接入点

针对同络接入点的安全性这一特定领域，本文旨在通过混合利用ebtables和iptables的网络过滤机制，构建一个基于Linux平台的透明网桥式的安全接入点。该接入点主机系统不仅能够作为一个透明网桥实现异构LAN之阍的桥接功能，同时还作为一个防火墙可根据用户的自定义安全策略，实施对于数据帧和数据包的双重过滤，因此可有效增强接入点的安全性。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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