NAT--网络地址转换技术在路由器中的实现

由于现行IP地址标准——IPv4的限制,INterbet面临着IP地址空间短缺的问题,从ISP申请并给每个客户端分配一个合法IP地址是不现实的。NAT(Network Address Translation)技术能较好解决现阶段IPV4地址短缺的问题。本文将针对NAT的作用及NAT的实现方法：静态地址转换技术、动态地址转换技术和端口地址转换技术进行详细阐述。     

简述NAT-网络地址转换

NAT（网络地址转换）通过将写在IP包上的未经注册的地址替换为合法的、已获注册的IP地址来解决地址冲突的问题。也就是说：在内部网络中使用内部地址,通过NAT把内部地址翻译成合法的IP地址,在Internet上使用,其具体做法是,给内部网络主机分配保留IP地址,在内部网络与Internet交接点设置NAT和一个由少量合法IP地址组成的IP地址池,在进行NAT转换时,将IP包内的地址域用合法的IP地址来替换,就可以解决大量内部主机用少量的IP地址访问互联网的需求了。 1 NAT分类 NAT技术有三种类型：静态NAT(static NAT)、ANT池(po…     

NAT技术在局域网中的应用

随着网络互联规模的不断扩大,全局IP地址短缺问题日益严重,NAT技术可有效地缓解IP地址空间枯竭的速度。本文深入分析了三种NAT技术的实现原理,在此基础上,以华为路由器为例说明其在局域网中的应用及具体配置方法。     

SIP与NAT工作冲突模型

SIP是一个应用层控制协议,NAT是私网IP地址和公网IP地址相互转换的一种技术,两者在网络上的使用都比较广泛。本文着重介绍了SIP与NAT协同工作时的冲突问题以及探讨了初步的解决方法。     

NAT技术在校园内部网络中的应用

采用NAT技术,可以使校园内部大量私有地址的计算机通过少数合法的IP地址上互联网,从而扩展互联网的能力,缓解IP地址不足的问题。通过在Cisco2611路由器上使用NAT技术,实现二级院系小型计算机网络上的所有计算机能同时上Internet,提高了学院计算机网络的应用效率。     

网络地址转换技术的实现与发展

网络地址转换（NAT）技术是解决当前Internet网络IP地址匮乏的一种有效手段，同时又是一项网络国界安全防范措施，本文在分析了NAT基本原理基础上，详细阐述了NAT网关的注册地址分配策略、路由策略、IP数据的修改以及安全和加密等技术细节，给出了NAT在网络层的实现策略，包括TCP／IP驱动系统的结构、IP协议在Linux中的实现和NAT技术在IP层的实现，最后，文章展望了NAT技术的发展趋势：端口地址转换PAT和NAT的跨主干网技术。     

在Windows 2000 Server中配置NAT

从公用地址和专用地址出发，引出使用NAT的必要性，进而讲述了NAT的工作原理及在Win2000 Senver中安装的方法，重点阐述了通过Win2000 Server自带的NAT来实现如何让一个专用网络中的所有主机共享一个公用IP上互联网进行通信，以及如何让一台公网上的主机去访问专用网络中一台主机。     

IPSec与NAT协同工作的一种解决方案

Internet网络层安全协议IPSEC和网络地址协议NAT不兼容,这严重限制了IPSEC的应用范围.解决的方法必须是既能使IPSEC数据流穿越NAT,又不必修改路由器和NAT,部署方便.本文分析了现有解决方案的局限性,对IETF(因特网工程任务组)提出的基于UDP封装的IPSec穿越NAT方案进行了改进,提出了一种新的封装格式,即封装整个IPSec数据报,将主机自身的IP地址一同进行封装,经过UDP封装后,其源地址被更改为原始IP地址,保护了原始IP地址和端口号,了IPSec报文对NAT设备的透明穿越.该方案通过对IPSec协议的扩展,有效地支持了IPSec数据流传输路径中的NAT转换.     

IPSec与NAT的冲突问题及其解决方案研究

分析了网络安全协议IPSec和网络地址转换协议NAT之间的冲突问题,并对IETF提出的现有UDP封装草案进行了改进,提出了一种新的封装格式,将主机自身的IP地址一同进行封装,以解决不兼容问题.从NAT网关内部发往NAT网关外部的数据包,在经过UDP解封装后,其源地址被更改为原始IP地址,因此目标主机的IP层以上各层将以原始地址为目的地址进行通信.利用改进后的UDP封装方案,实现了IPSec报文对NAT设备的透明穿越.该方案通过对IPSec协议的扩展,有效地支持了IPSec数据流传输路径中的NAT转换.     

局域网地址转换技术的应用

随着Internet的飞速发展，IPV4下可用的IP地址越来越少，NAT（网络地址翻译）技术的实现除了能解决IP地址紧张的问题外，还可以完成隔离外网、保护局域网安全以及负载平衡等功能。本文主要介绍了网络地址转换技术的实现过程，并对NAT的负载均衡能力、加密与安全、优缺点等问题进行了需要分析。     

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     

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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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has