局域网毕业论文文献翻译中英文对照

1、 外文资料及中文译文院系名称 信息科学与技术学院 学生姓名 学生学号 _ 200503013098 专业班级 _ 计科03- 7 指导教师 外文资料出处：计算机世界报 第03期 c20a lan may be created based on a peering or a client-server. small lans are of ten created based on a simple peering relationship. users may share resources and communicate with one another on a peer network,

2、but no single computer controls a peer network, and peer network users do not typically centralize files on one machine. as a rule, peer networks tend to lack organization and adequate security controls.the client-server architecture is usually used for sever controls network access and network reso

3、urces. clients request resources from the server, and the server provides resources to clients. servers may range in complexity from mainframes to pcs. clients may range in complexity from pcs to display to terminals (dts). client-server networks provide strong central security, centralized file org

4、anization and storage, and centralized data preservation. compared to a peer network, a client-server network requires more centralized and specialized administration.along with the rapid scientific and technological development, computer use in production as a proportion growing, increasingly play

5、a decisive role in the ministry, the office has computers, greatly facilitate the departments work, another demand gradually reveal themselves. that is the single transmission of information between. computer networks should be established as soon as possible on the agenda. establish computer networ

6、ks main purpose is to realize a resource sharing that all network users can enjoy the computer systems of all or part of the resources.lan are currently used to broadcast the technical basis for ethernet, any two nodes of communication between the data packet is not only these two nodes by the card

7、receipt, were also at the same ethernet to the nodes of a network card by the interception, as long as hackers access to the ethernet nodes for an interception, can capture the ethernet in the data packet and all its packet analysis solution, thereby stealing critical information, this is the ethern

8、et inherent security risks. in fact, many on the internet free of the hacking tools are put ethernet interception as the most fundamental means. a firewall is a network device that enforces security policy for network traffic. the term originates from firewall, a fireproof wall used as a barrier to

9、prevent the spread of fire. an internet firewall creates a barrier between separate networks by imposing a point of control that traffic needs to pass before it can reach a different network. a firewall may limit the exposure of hosts to malicious network traffic, e.g., remote adversaries attempting

10、 to exploit security holes in vulnerable applications, by preventing certain packets from entering networks protected by the firewall.when inspecting a network packet, a firewall decides if it should drop or forward the packet. the decision is based on a firewalls security policy and its internal st

11、ate. before forwarding a packet, a firewall may modify the packets content. packet inspection may occur at several different layers: (1)the link layer provides physical addressing of devices on the same network. firewalls operating on the link layer usually drop packets based on the media access con

12、trol (mac) addresses of communicating hosts. (2)the network layer contains the internet protocol (ip) headers that support addressing across networks so that hosts not on the same physical network can communicate with each other. (3)the transport layer provides data flows between hosts. on the inter

13、net, the transmission control protocol (tcp) and the user datagram protocol (udp) are used for this purpose. most firewalls operate at the network and transport layer. tcp provides reliable data flow between hosts. udp is a much simpler but unreliable transport protocol. (4)the application layer con

14、tains application specific protocols like the hypertext transfer protocol (http). inspection of application specific protocols can be computationally expensive because more data needs to be inspected and more states are required. a firewall is a piece of software or hardware that helps screen out ha

15、ckers, viruses, and worms that try to reach your computer over the internet. if you are a home user or small-business user, using a firewall is the most effective and important first step you can take to help protect your computer. it is important to have a firewall and antivirus software turned on

16、before you connect to the internet. if your computer is not protected when you connect to the internet, hackers can gain access to personal information on your computer. they can install code on your computer that destroys files or causes malfunctions. they can also use your computer to cause proble

17、ms on other home and business computers connected to the internet. a firewall helps to screen out many kinds of malicious internet traffic before it reaches your system. some firewalls can also help to prevent other people from using your computer to attack other computers without your knowledge. us

18、ing a firewall is important no matter how you connect to the internet dial-up modem, cable modem, or digital subscriber line (dsl or adsl). the firewall product main bastion of the mainframe, packet-filtering router, application layer gateway (proxy), and circuit gateway, shielding mainframe firewal

19、ls, and other mainframe-type places. although the firewall is to protect the network from hacker attacks effective means, but there are clearly inadequate: unable to prevent outside the firewall through other means of attack, not prevent defection from within and not attentive to the customers who b

20、rought the threat, able to completely prevent transmission of the virus has infected software or documents, and can not prevent data-driven attacks. since 1986 digital companies in the united states to install the internet world, a commercial fire wall system, the concept of a firewall after firewal

21、l technology has made rapid development. dozens of domestic and foreign companies launched the function of the firewall is not the same product range. 5 firewall at the network layer security system at the bottom of belonging to the network layer security technology areas. in this layer, the busines

22、s-to-security system raised of the question: whether all the ip can visit to the enterprises internal network? if the answer is yes, is illustrated in internal network has no network layer take preventive measures. as the internal network and external public network between the first barrier firewal

23、l is the first by the peoples attention to the network security products in one. although theoretically, firewall network security at the bottom, the network responsible for the security authentication and transmission, but with network security technology development and application of the network

24、changes, modern technology has gradually firewall to the network layer other than the safety level, not only to complete the traditional firewall filtering tasks, but also for the various networks to provide the corresponding security services. in addition there is many other firewall products are m

25、oving towards data security and user authentication, anti-virus and hacker intrusion direction. smes in the specific network environment, in addition to hiv and the birthright of transmissibility, enforceability, and conventional destructive virus in common, but also have some other features: 1. fas

26、ter rate of infection the spread of the virus must be some means for the complete closure of the single case; the virus is not from one computer to another computer transmission of. but the simple enterprise network environment, the spread of the virus can fully use the media, simple and rapid adopt

27、ion of the internal network, the virus can spread rapidly, for example: common in the 100 m office network, as long as one is exposed workstations, can be in the tens of seconds to the same network of several hundred computers infected all. 2. wide spread infection of a particular lan client taiwan,

28、 and the client can also further infection of other network client (including servers) infected with the virus and the client can further infection more client (including a computer outside the lan) so many cross-infection, the virus spread in the network, in addition to speed, its spread is quite a

29、mazing. 3. dissemination in the form of complex and diverse network forms of transmission of the virus before we have already done a presentation here would not elaborate on the but with computer viruses innovation, i believe there will be even more we can not predict the form of dissemination. 4. d

30、ifficult to eradicate single of computer viruses can sometimes through anti-virus and virus deleted documents to resolve. if that does not work, such as low-level disk formatting can measure the complete removal of the virus. network, as long as they have a workstation could not cleanse, the whole n

31、etwork can be re-infected with the virus, have just completed a work of the anti-virus workstations, it may be another virus internet workstations are infected. therefore, to deal with the single form of anti-virus, the lan will be more pronounced, felt helpless. 5. devastating smes office network i

32、s mainly for enterprise services. virus attacks, the network will not only affect their normal work, and even more frightening is that it would collapse the network, damage to the computer network, so that work was ruined. 6. sexual sparks it can be described as the hidden nature of the virus on the

33、 network extension, the network conditions for the virus to stimulate the diversification, it is the internal clock, the date and user name, it can also be a network of communication and so on. an hiv virus in accordance with the procedures designers, at the request of a workstation outbreak and spr

34、ead to the entire network. 7. potential in the network, once infected with the virus, even if the virus has been eliminated, the potential danger is enormous. according to the companys network statistics, the virus has been removed, 85% of the 30 days will be re-infection. enterprises still using si

35、ngle version of anti-virus software virus defense at the same time, virus has in various forms through the lan to spread quickly, and they attacked the client, server, and gateway, almost all pervasive. it is not exaggerating to say, we can easily make the entire lan gridlock, should we really have

36、to sit until death?although the prospect of using virus technology to simplify the task of delivering patches and software updates is tempting, the dangers can outweigh the benefits when the process is too automated. for example, the improved windows update feature in windows xp now allows patches a

37、nd updates to be downloaded automatically, although installation is still at the users discretion. trojan horses, worms, and other malicious code forms have proven to be incredibly successful at paralyzing e-mail systems and internet providers. it is therefore only logical to conceive of ways to use

38、 them for productive purposes, much as the bible exhorts its readers to beat their swords into plowshares and their spears into pruning hooks. granted, it would be wonderful if it administrators could distribute patches and software updates to desktops and servers as quickly as an e-mail virus can s

39、pread from one machine to the next. but is such a magic wand really a good idea? well, maybe not exactly. after all, unlike the human immune system, which produces defenses, or antibodies, automatically, the computer must wait for a human to analyze samples of a computer virus, prepare antidotes and

40、 vaccines for that specific situation, and only then apply the cure. this observation alone would seem to discredit the idea of a “digital immune system” that the security community has tossed around during the past few years, but theres an even more important point to consider. similar to the way t

41、hat autoimmune diseases turn the body s own defenses against itself, so could one turn a viruslike software delivery system against its own computers. although it would be difficult to monkey with the digital certificates that would conceivably be used to identify trusted patches, its not impossible

42、 to subvert the certificate issuing system.viruses, worms, and trojan horses are programs created by hackers that use the internet to infect vulnerable computers. viruses and worms can replicate themselves from computer to computer, while trojan horses enter a computer by hiding inside an apparently

43、 legitimate program, such as a screen saver. destructive viruses, worms, and trojan horses can erase information from your hard disk or completely disable your computer. others dont cause direct damage, but worsen your computers performance and stability.antivirus programs scan email and other files

44、 on your computer for viruses, worms, and trojan horses. if one is found, the antivirus program either quarantines (isolates) it or deletes it entirely before it damages your computer and files.because new viruses are identified every day, its important to select an antivirus program with an automat

45、ic update capability. when the antivirus software is updated, it adds new viruses to its list of viruses to check for, helping to protect your computer from new attacks. if the list of viruses is out of date, your computer is vulnerable to new threats. updates usually require an annual subscription

46、fee. keep the subscription current to receive regular updates.tips for using email and the web safely:(1)use caution when opening email attachments. email attachments (files attached to email messages) are a primary source of virus infection. never open an attachment from someone you dont know. if y

47、ou know the sender but were not expecting an attachment, verify that the sender actually sent the attachment before you open it. see when to trust an email message and avoiding email viruses.(2)guard your personal information carefully. if a website asks for a credit card number, bank information, o

48、r other personal information, make sure that you trust the website and verify that its transaction system is secure. (3)use the phishing filter in internet explorer. phishing is the practice of creating fraudulent email messages and websites in order to trick computer users into revealing personal o

49、r financial information. the fraudulent email message or website appears to be from a trusted source, such as a bank, credit card company, or reputable online merchant. the phishing filter helps detect phishing websites to protect you from scams.(4)be careful when clicking hyperlinks in email messag

50、es. hyperlinks (links that open websites when you click them) are often used as part of phishing and spy ware scams, but they can also transmit viruses. (5)only install add-ons from websites that you trust. web browser add-ons, including activex controls, allow web pages to display things like toolb

51、ars, stock tickers, video, and animation. however, add-ons can also install spy ware or other malicious software. if a website asks you to install an add-on, make sure that you trust it before doing so. 中文译文局域网可以基于对等式网络中，用户可以彼此共享资源和进行交流，但没有一台计算机对整个网络进行控制，对等式网络的用户一般也不将文件集中在一台机器上，通常对等网络往往缺少组织性和足够的安全控制

52、。客户机-服务器结构经常用于大型局域网或对安全性要求很高的局域网中。在客户机服务网络中，服务器控制网络的访问和网络的资源。客户机向服务器请求资源，服务器向客户机提供资源，从类型机到pc机，服务器的复杂程度各不相同。从pc机到显示终端（dts），客户机的复杂程度也不相同。客户机服务器网络提供强大的中央安全控制，集中对文件进行组织和存储，并集中对数据进行保护。与对等网络相比，客户机服务器网络需要更多的集中管理和专门管理。目前局域网上都是采用以广播为技术基础的以太网，任何两个节点之间的通信数据包不仅被这两个节点的网卡所接收，也同时被处于同一以太网上的任一节点的网卡所截取，黑客只要接入以太网上的任一节

53、点进行侦听，就可以捕获发生在这个以太网上的所有数据包并对其进行解包分析，从而窃取关键信息，这就是以太网所固有的安全隐患。事实上，internet上的很多免费的黑客工具都是把以太网侦听作为其最基本的手段。防火墙是一种网络设备，为网络的交通执行安全政策。这一术语来源于防火墙，防火墙作为防止火势蔓延的一道屏障。一个互联网防火墙造成障碍之间的单独网络设定点，控制交通需求，以通过才能达到不同网络。防火墙可以限制暴露主机恶意网络流量，例如，远程对手企图利用安全漏洞易受申请防止某些数据包进入网络保护的防火墙。当考察了网络数据包时，防火墙决定是否应该减少或转发数据包，这项决定是基于防火墙的安全策略及其内部状态

54、。在转发包以前，防火墙可以修改数据包的内容。包检查可能发生在几个不同的层次：（1）链路层在同一网络提供物理处理设备。防火墙运行在链路层，往往使得包难于与体访问控制(mac)地址的主机沟通。（2）网络层包含的互联网协议(ip)报头，支持解决跨网络，使主机不在相同的物理网络上也与对方沟通。（3）运输层提供了数据流之间的主机。在因特网上传输控制协议(tcp)和用户数据报协议(udp协议)是用于这一目的。大多数防火墙运行在网络和传输层。tcp协议在主机之间提供可靠的数据流，udp协议是一个非常简单，但不可靠的传输协议。（4）应用层包含应用特定的协议，像超文本传输协议(http)，可以统计昂贵的特定应用

55、协议的检查，因为更多的数据需要加以检查，并有更多的国家所需。防火墙是一个软件或硬件，有助于筛选出黑客，病毒与蠕虫，设法让你的电脑接入因特网。如果你是一位家庭用户或小型企业用户，使用防火墙是最有效和最重要的第一步，它可以帮助您保护计算机。它是重要的，是有一个防火墙和防毒软体开启，然后连接到互联网上的。 如果你的电脑是没有保障，当您连接到互联网，黑客在您的计算机上可获取个人资料。他们可以安装程序码输入电脑，销毁档案或导致故障。其他家用和商用电脑连接上互联网，他们也可以使您的电脑造成问题。在到达你的系统之前，防火墙有助于筛选出多种恶意网络流量。没有你的知识，部分防火墙也能防止其他人使用你的电脑攻击其

56、他电脑。使用防火墙重要的是你是怎样连接到互联网拨号调制解调器，电缆调制解调器，或数字订户线路(dsl或adsl的)。目前的防火墙产品主要有堡垒主机、包过滤路由器、应用层网关(代理服务器)以及电路层网关、屏蔽主机防火墙、双宿主机等类型。虽然防火墙是目前保护网络免遭黑客袭击的有效手段，但也有明显不足：无法防范通过防火墙以外的其它途径的攻击，不能防止来自内部变节者和不经心的用户们带来的威胁，也不能完全防止传送已感染病毒的软件或文件，以及无法防范数据驱动型的攻击。自从1986年美国digital公司在internet上安装了全球第一个商用防火墙系统，提出了防火墙概念后，防火墙技术得到了飞速的发展。国内

57、外已有数十家公司推出了功能各不相同的防火墙产品系列。防火墙处于5层网络安全体系中的最底层，属于网络层安全技术范畴。在这一层上，企业对安全系统提出的问题是：所有的ip是否都能访问到企业的内部网络系统?如果答案是“是”，则说明企业内部网还没有在网络层采取相应的防范措施。作为内部网络与外部公共网络之间的第一道屏障，防火墙是最先受到人们重视的网络安全产品之一。虽然从理论上看，防火墙处于网络安全的最底层，负责网络间的安全认证与传输，但随着网络安全技术的整体发展和网络应用的不断变化，现代防火墙技术已经逐步走向网络层之外的其他安全层次，不仅要完成传统防火墙的过滤任务，同时还能为各种网络应用提供相应的安全服务

58、。另外还有多种防火墙产品正朝着数据安全与用户认证、防止病毒与黑客侵入等方向发展。在中小型企业网络的特定环境下，病毒除了与生俱来的可传播性、可执行性、破坏性等常规病毒的共性外，还具有一些其他的特点：1、感染速度快病毒的传播必须要一定的途径，在完全封闭的单机情况下，病毒是无法从一台计算机传给另一台计算机的。不过在企业简单的网络环境下，病毒的传播可以利用充分的介质，通过简单而快速的内部网络，病毒可以迅速地传播，举个例子：在常见的100m办公网络内，只要有一台工作站染毒，就可在几十秒钟内将同一网络中的数百台计算机全部感染。2、扩散面广病毒感染了局域网中某一台客户机，而客户机又可以进一步感染网络中的其他客户机（也包括服务器），而感染了病毒的客户机又可以更进一步的感染更多客户机（也包括了局域网以外的计算机）如此反复交叉感染