计算机专业科技论文英文免费下载

计算机专业科技论文英文免费下载

免费下载论文的话~你就应该去找一些开源性的期刊~像（计算机科学与应用、国际航空航天科学）等等这样的~开源类的期刊都是可以免费下载和查阅的~

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一些能下载英文文献的网站都可以，比如爱学术网站，是中英文结合的，就可以下载。

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计算机专业科技论文免费下载

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计算机科学与技术专业本科生毕业论文2007年11月10日 星期六 21:43xxxxxx大学本科生毕业论文密码技术研究—密码破解院 系：计信系 专 业：计算机科学与技术专业学生班级：2005级(函授本科)姓 名：学 号：指导教师姓名：xx目 录摘要 ……………………………………………………………… 1关键词 …………………………………………………………… 1第一章 引言 …………………………………………………… 1第二章 攻击者如何及为何进行攻击 ………………………… 1第三章 攻击者闯入系统的利器 ……………………………… 2第四章 攻击者如何攻击及停止或预防 ……………………… 3第五章 结束语 ………………………………………………… 6参考文献 ……………………………………………………… 7SummaryThe valid exploitation of the password and the customer bank account is one of the biggest problems of the network Will study the password to break the solution in this thesis:How carry on some break the solution and why carry on the password to break the The attack that wants to carry on to the calculator system of the company or organization contain various form， for example:The electronics cheat， the brush-off service( DoS) attack of the smurf attack and other These attacks were design break or break off the usage of your luck camp This text discuss a kind of widely for the attack form that spread， be called the password to break the In addition return to permeate elucidation the network is how simple， aggressor how enter its method of tool and the anti- shots that network， they Keyword: Password Break the solution attack Safety Permeate Network Protection摘 要密码与用户帐户的有效利用是网络安全性的最大问题之一。在本论文将研究密码破解：如何进行一些破解以及为何进行密码破解。要对公司或组织的计算机系统进行的攻击有各种形式，例如：电子欺骗、smurf 攻击以及其它类型的拒绝服务（DoS）攻击。这些攻击被设计成破坏或中断您的运营系统的使用。本文讨论一种广为流传的攻击形式，称为密码破解。此外还将说明渗透网络是多么简单，攻击者如何进入网络、他们使用的工具以及抗击它的方法。关键词：密码 破解 攻击 安全性 渗透 网络 防护第一章 引言密码破解是用以描述在使用或不使用工具的情况下渗透网络、系统或资源以解锁用密码保护的资源的一个术语。本文将研究什么是密码破解、为什么攻击者会这样做、他们如何达到目的，以及如何保护自己免受攻击。我将简要研究攻击者自身：他们的习性和动机。通过对几种方案的研究，我将描述他们部署的一些技术、帮助他们攻击的工具以及密码破解者是如何从内部和外部侵犯公司基础结构的。在研究这样做的一些方法之前，让我们首先了解攻击者的想法并研究他们为什么想访问您的网络和系统。第二章 攻击者如何及为何进行攻击关于黑客的定义仍然争论不休。黑客可以是任何对基于计算机的技术有浓厚兴趣的人；它未必定义想进行伤害的人。词汇攻击者可用来描述恶意黑客。攻击者的另一个词汇是黑帽。安全分析师通常称为白帽，白帽分析是为防御目的而使用的密码破解。攻击者的动机差别很大。有些声明狼籍的黑客是高中生，他们在地下室里的电脑前寻找利用计算机系统的漏洞的方法。其它攻击者是寻求报复公司的心怀不满的雇员。还有另外一些攻击者完全出于寻求刺激性的挑战目的，想渗透保护良好的系统。攻击方法中密码破解不一定涉及复杂的工具。它可能与找一张写有密码的贴纸一样简单，而这张纸就贴在显示器上或者藏在键盘底下。另一种蛮力技术称为“垃圾搜寻”，它基本上就是一个攻击者把垃圾搜寻一遍以找出可能含有密码的废弃文档。当然，攻击者可以涉及更高级的复杂技术。这里是一些在密码破解中使用的更常见的技术： 字典攻击（Dictionary attack） ：到目前为止，一个简单的字典攻击是闯入机器的最快方法。字典文件被装入破解应用程序，它是根据由应用程序定位的用户帐户运行的。因为大多数密码通常是简单的，所以运行字典攻击通常足以实现目的了。 混合攻击（Hybrid attack） ：另一个众所周知的攻击形式是混合攻击。混合攻击将数字和符号添加到文件名以成功破解密码。许多人只通过在当前密码后加一个数字来更改密码。其模式通常采用这一形式：第一月的密码是“cat”；第二个月的密码是“cat1”；第三个月的密码是“cat2”，依次类推。 蛮力攻击（Brute force attack）：蛮力攻击是最全面的攻击形式，虽然它通常需要很长的时间工作，这取决于密码的复杂程度。根据密码的复杂程度，某些蛮力攻击可能花费一个星期的时间。在蛮力攻击中还可以使用 L0phtcrack。第三章 攻击者闯入系统的利器最常用的工具之一是 L0phtCrack（现在称为 LC5）。L0phtCrack 是允许攻击者获取加密的 Windows NT/2000 密码并将它们转换成纯文本的一种工具。NT/2000 密码是密码散列格式，如果没有诸如 L0phtCrack 之类的工具就无法读取。它的工作方式是通过尝试每个可能的字母数字组合试图破解密码。这也一款网络管理员的必备的工具，它可以用来检测Windows、UNIX 用户是否使用了不安全的密码，同样也是最好、最快的Win NT/2000/XP/UNIX 管理员帐号密码破解工具。事实证明，简单的或容易遭受破解的管理员密码是最大的安全威胁之一，因为攻击者往往以合法的身份登陆计算机系统而不被察觉。另一个常用的工具是协议分析器（最好称为网络嗅探器，如 Sniffer Pro 或 Etherpeek），它能够捕获它所连接的网段上的每块数据。当以混杂方式运行这种工具时，它可以“嗅探出”该网段上发生的每件事，如登录和数据传输。这可能严重地损害网络安全性，使攻击者捕获密码和敏感数据。第四章 攻击者如何攻击及停止或预防我将首先描述两种涉及内部攻击的方案（即，在组织内部发起的攻击），然后研究涉及外部攻击的两种方案。内部攻击：内部攻击者是解密攻击最常见的来源，因为攻击者具有对组织系统的直接访问权。第一种是攻击者是心怀不满的雇员的情况。攻击者，一名经验丰富的系统管理员，在工作中遇到了问题，而拿自己管理、保护的系统发泄。示例：心怀不满的雇员JaneSmith是一名经验丰富的且在技术上有完善的记录证明的系统管理员，她被公司雇佣在深夜运行备份磁带。公司，作为一家 ISP，拥有非常庞大的数据中心，大约4000多个系统都由一个网络运营中心监控。Jane和另外两名技术人员一起工作以监控通宵备份，并且在早班之前倒完磁带。他们彼此独立工作：一名技术员负责UNIX服务器，一名技术员负责全部Novell服务器，而Jane负责Windows服务器。Jane已经工作了六个月并且是一名后起之秀。她来得很早，走得很晚，并且曾请求转到公司的另一个部门。问题是那时没有空位子。在上个月，安全分析师发现Cisco路由器和UNIX服务器上的登录尝试的数量有大幅增加。由于实现了CiscoSecureACS，所以可以对尝试进行审计，发现它们大部分出现在早上 3 点钟。怀疑产生了，但作为一名安全分析师，不能在没有证据的情况下到处指证。一名优秀的安全分析师从深入研究问题着手。您发现攻击出自高手，并且出现在Jane当班期间，正好在她完成倒带任务之后，在日班小组到来之前，她有一个小时的时间学习和阅读。所以公司决定请夜班经理夜晚监督Jane。三个星期的严密监督之后，发现攻击已经停止了。怀疑是正确的，正是Jane试图登录到Cisco路由器和UNIX服务器中。因此，一名优秀的安全分析师还需要使用一种好的审计工具（如 Tacacs+）来记录攻击。Tacacs+是由诸如CiscoSecureACS之类的应用程序所使用的协议，该协议强制授权、可计帐性和认证（简称 AAA）。如果具有授权，则需要对请求访问的人进行授权以访问系统。如果具有认证，则需要对访问资源的用户进行认证以验证他们是否有访问的权利和权限。如果同时被授权和认证会发生什么呢？必须具有可计帐的。单独计算登录数通过强制攻击者保持可计帐的、被认证及被授权，从而解决了许多密码破解问题。接下来，将给出一个仍广泛使用的攻击示例，它就在网下嗅探密码。可以研究一下网络主管的 Cisco 路由器和交换机是如何被公司中的 Help Desk 技术人员破解的。示例：HelpDesk技术人员Tommy 被雇佣担任 Help Desk 技术员，他和下班后的 Help Desk 人员一起工作。下班后的 Help Desk 人员由大约 10 名技术员组成，他们负责公司需要在下班期间支持的 8 个远程站点。Tommy 总是带着他的笔记本电脑上班。当经理问及此事时，Tommy 解释说他用其休息时间准备一个认证考试。这似乎是无害的并得到了批准，尽管公司对在未经公司安全检查就从外部将机器带入公司网络的行为有一条公司内的安全制度。最终，一个监视器捕获了 Tommy 在离开一间小配线房时在手臂下藏着某些东西。但由于无人报告丢失任何东西，无法证明 Tommy 犯了什么错。当 Help Desk 经理询问 Tommy 为什么出现在配线房时，他说误把配线房当成了休息室。公司安全经理 Erika 看到了由负责大楼安全的门卫提交的报告。她想知道 Tommy 在配线房干什么，并且对 Tommy 向 Help Desk 经理的回答感到怀疑。检查配线房时，她发现从其中一个配线板上垂下一根被拔下的接线电缆以及一个空的集线器端口。当她将电缆插回去时，链路灯还是不亮，这意味着这是一个死端口。电缆管理员 Velcro 将所有其它电缆都整齐地捆绑在一起。凭着 Erika 多年经验以及对安全利用的敏锐意识，她确切地知道发生了什么。Erika 假设 Tommy 在未被发现的情况下将其笔记本电脑带入了配线房。他很有可能寻找集线器上的一个死端口，然后插上安装了包嗅探器的笔记本电脑，该嗅探器可以不加选择地拾取网段上的通信量。稍后他返回取走了电脑（被监视器捕捉到），在保存捕捉文件后拿回家进行分析。使用公司的安全制度，她找到 Tommy 并说明了所有非法进入公司的个人财产（如笔记本电脑和掌上电脑）都需要进行检查。由于 Tommy 本不该带入他的笔记本电脑，所以将它交给了 Erika。经过仔细检查，Erika 发现了跟踪译码。经过对 Sniffer Pro 分析器十六进制窗格的严格检查，在窗格的右边清晰地显示了 ASCII 数据。当连接到配线房的交换机时，Tommy 通过 telnet 会话连接在运行配置。由于 telnet 协议是不安全的且通过明文发送，所以很容易看到密码“cisco”。这是最基本的安全性原则之一：不要使用产品名称作为密码。外部攻击：外部攻击者是那些必须透过您的“深度防御”试图闯入您系统的人。他们做起来并不象内部攻击者那样容易。第一种是一种很常见的外部攻击形式，称为网站涂改。这一攻击使用密码破解来渗透攻击者想破坏的系统。另一个可能的密码破解攻击是攻击者尝试通过社交工程（Social Engineering）获取密码。社交工程是哄骗一个毫无疑虑的管理员向攻击者说出帐户标识和密码的欺骗方法。让我们对这两种方案都研究一下。示例一：网站主页涂改。通常只要通过利用未正确设置其权限的 Internet Information Server (IIS) 就可以完成。攻击者只要转至工作站并尝试使用 HTML 编辑工具攻击 IIS 服务器。当试图通过因特网连接到该站点时，攻击者使用一个密码发生器工具（如 L0phtCrack），它启动对服务器的蛮力攻击。示例二：社交工程骗局。不需要工具而破解密码的骗局称为社交工程攻击。Jon 是一家大公司的新任安全分析师。他的首要工作是测试公司的安全状态。他当然要让管理层知道他将要做什么（这样，他自己就不会被当成攻击者）。他想知道要闯入网络而不使用任何工具的难度如何。他尝试两个单独但破坏性相同的攻击。作为大公司的新雇员，很多人还不认识 Jon，这使他能容易地完成第一个社交工程攻击。他的第一个目标是 Help Desk。Jon 给 Help Desk 打了一个常规电话，作为假想的远程用户要求密码重设。由于 Jon 知道公司的命名约定是用户的名字加上其姓的第一个字母，他已经有了他需要的一半信息。CIO 的名字是 Jeff，他的姓是 Ronald，因此他的登录标识是 JeffR。这条信息可以从公司的电话目录中轻易地得到。Jon 假装成 CIO 打电话给 Help Desk 并要求密码重设，因为忘记了密码。Help Desk 技术人员每天都要重设上百次被遗忘的密码，然后回电让请求者知道其新密码，这对于他们来说是常规工作。5 分钟后，Help Desk 技术人员给 Jon 回电话，告诉他新的密码是“friday”，因为恰好是星期五。5 分钟之内，Jon 就进入了服务器上 CIO 的共享文件及其电子邮件了。Jon 的下一个社交工程攻击涉及他的一个好朋友，此人为当地电话公司工作。Jon 在他休假时借了他的衣服、皮带和徽章。Jon 穿着他的新衣服进入公司存放所有灾难恢复路由器和服务器的另一部分场地。这个硬件包含公司的所有当前数据的有效副本并且认为是机密。Jon 穿着他的电信制服走入场地安全办公室，然后说明他是由本地交换运营商（Local Exchange Carrier (LEC)）派来的，因为看来电路从电话公司形成了回路。他需要被允许进入数据中心，这样他可以检查在 Smart Jack 上是否有任何警报。现场管理员陪同 Jon 到数据中心，甚至没有检查他的标识。一旦进入，管理员明智地站在一边，这样 Jon 开始了他的测试。几分钟后，Jon 通知管理员他必须打电话给办公室并请他们再运行一些测试，以便能断开到 Smart Jack 的回路并尝试故障诊断。Jon 让管理员知道这将花费 45 分钟，因此管理员向 Jon 提供了他的呼机号，并请在 Jon 完成时呼他以让他出来。Jon 现在成功地排除了他和数据中心沿墙的机架上排列的 30 台服务器之间的唯一障碍。Jon 现在有几个不同的机会。他可以转至每个服务器，然后查找未加锁的控制台或者他可以将其笔记本电脑插入开放端口并开始嗅探。由于他确实想知道自己能走多远，所以决定查找开放的控制台。花 5 分钟查看所有 KVM 槽后，他发现 Windows NT 服务器是作为域的备份域控制器（Backup Domain Controller）运行的。Jon 从包中拿出一张 CD，然后将它放入服务器的 CD 托盘。他将 L0phtCrack 安装到公司域的 BDC 上，然后运行字典攻击。5 分钟之内，产生了如下密码：Yankees。它表明首席管理员是一个纽约 Yankee 迷。他现在已经有了对公司最重要的信息的访问权。如何预防攻击：依照下列方法进行检查，可以使密码破解更加困难。1、进行审查。确保没有将密码贴在监视器或键盘底下。 2、设置哑帐户。除去 administrator（或 admin）帐户，或将其设置为陷阱并对其尝试进行审查。3、使用难以猜测的密码，永远不要让控制台处于解锁状态。 4、备份是必需的以防不测。也要保护备份，否则也可能遭到损坏。 5、防止垃圾搜寻。不要乱扔敏感信息；撕碎它或把它锁起来。 6、检查标识并讯问不认识的人。7、加强认识。确保不受社交工程的侵害。 8、安装可靠的防火墙及杀毒软件。第五章 结束语本论文中，我描述了攻击者动机之后的某些心理以及用来破解密码的一些低技术和高技术方法。看到了几种攻击方案，包括由经验丰富的管理员、技术人员和外部故意破坏者对大公司发起的攻击。了解了密码破解者如何在内部和外部使用技术攻击您的基础结构。最后，提供了有关如何适当保护自己和系统避免可能受到密码破解攻击的一些想法。参考文献[1] 《电脑报2003年合订本》；西南师范大学出版社[2] 《电脑报2004年合订本》；西南师范大学出版社[3] 《电脑报2005年合订本》；西南师范大学出版社[4] 《电脑报2006年合订本》；西南师范大学出版社[5] 《电脑迷2004年合订版》；西南交通大学出版社[6] 《电脑迷2005年合订版》；西南交通大学出版社[7] 《电脑迷2006年合订版》；西南交通大学出版社[8] 《黑客奇技赢巧大搜捕》；电脑报社发行部

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Information literacy Knowing how to find data from several sources， select relevant material， analyse and organise it into a form that can be used to make Computers have become the tools people use to access and manage Information technologists are people who analyse and design the What is a computer? Tradition definitions of computers include • A machine that accepts data and processes it into use • A computer is a binary， digital， electronic， stored program • While a computer is commonly a digital machine， analogue machine do An electronic device， operating under the control of instructions stored in its own memory unit， that can accept data (input)， process data arithmetically and logically， produce results (output) from the processing and stores results for future Many computers receive and send data (communicate) across networks LAN and W A computer system consists of hardware and What is hardware? Hardware Hardware is physical devices or components that can be physically handled – you can thou Input Devices Input devices convert data that humans collect into coded electrical signals that a computer can The central processing unit The electronic processing takes place in the CPU The CPU consists of • A control unit that controls all of the computer’s functions and an • Arithmetic and logical unit (ALU) that performs any calculation Memory Memory holds all programs and What is RAM currently open? Data (notes) Word processor OS Output devices Output devices convert the computer’s electronic signals back into information Secondary storage devices These devices store programs and data The programs and data are not necessarily (or likely to be) in current E DVD CD Communication devices These devices enable a computer to connect to another List the six different type of hardware? Secondary storage(external)， input， processor， output ， memory， C Name eight pieces of hardware USB， keyboard， monitor， screen， RAM， ROM， VDU， M The system unit and peripheral devices The system unit is the computer Peripheral devices are any devices around the outside， or in other words， plugged into the (back of) the Peripheral devices include the key board， mouse， printer， joy stick and Peripheral devices are any devices around the outside， or in other words， plugged into the (back of) the Peripheral devices include the keyboard， mouse， printer， joy stick and What else does a computer have? Software Software is a computer program ，which is a detailed set of instructions that directs a computer to perform the tasks necessary to process data into These instructions are written in languages that computer can Software includes computer games， a word processing packing， an accounting package， amongst Definition of a computer system • A computer system is the configuration of hardware and software， functioning together， to process data into useful information， in order to achieve a purpose for a human What is data? • Data is raw facts， be they numbers， words， images and sounds， that can be input into a Mary a name is a piece of data What is information? • Information is processed data， that has meaning and is John is a list of names who scored an A grade on an exam John A Chai A Pam A Commodore $23 500 Magna $21 500 Falcon $19 800 The system unit contains the • Motherboard • CPU • Memory • Other electronics It is where the computer program instructions are executed and the data is manipulatedThe Processor CPU The CPU interprets and carries out basic instructions that operate the computer， the CPU contain the • Control unit and the • Arithmetic logic unit Control unit The control unit directs and coordinates the computer’s For every single instruction， the control unit repeats four basic operations， • Fetching • Decoding • Executing • Storing CPU speed The CPU’s speed may be measured in MIPS The number of millions of instructions per second Arithmetic/logic unit The ALU performs all calculations， which involve • Arithmetic operations 2+3 • Comparison operations age>=17 • Logical operations pass Processing instructions A CPU may begin executing a second machine cycle before completing the first-referred to as Current CPU’s can pipeline up to 4 Storage within the CPU Registers temporarily hold data and The computer’s clock A System clock is necessary to control the timing of all computer Each tick of the clock is referred to as a clock Clock speed is the speed at which a processor executes A hertz is one cycle per second and a megahertz is 1024 by1024 and a gigahertz is 1024 by 1024 Memory Memory is the temporary storage place for data and (program) Memory is measured in • Kilobytes 1024 bytes 2^10 • Megabytes 1024* 1024 bytes 2^20 • Gigabytes 1024*1024*1024 bytes 2^30 Representation of data Digital computers are built from many small electronic Each circuit， at any point of time can be turned OFF or ON Hence these devices are called two state Binary Digit 0and 1 Each off or on digital value is called a bit， short for binary A 1 bit computer would be able to distinguish between two values-characters， symbols or Hardly sufficient for the characters on the keyboard Bits Characters 1 2 2 4 3 8 4 16 5 32 6 64 7 128 8 256

海外英语杂志欢迎投稿，详情见我的空间

Information literacy Knowing how to find data from several sources， select relevant material， analyse and organise it into a form that can be used to make Computers have become the tools people use to access and manage Information technologists are people who analyse and design the What is a computer? Tradition definitions of computers include �6�1 A machine that accepts data and processes it into use �6�1 A computer is a binary， digital， electronic， stored program �6�1 While a computer is commonly a digital machine， analogue machine do An electronic device， operating under the control of instructions stored in its own memory unit， that can accept data (input)， process data arithmetically and logically， produce results (output) from the processing and stores results for future Many computers receive and send data (communicate) across networks LAN and W A computer system consists of hardware and What is hardware? Hardware Hardware is physical devices or components that can be physically handled – you can thou Input Devices Input devices convert data that humans collect into coded electrical signals that a computer can The central processing unit The electronic processing takes place in the CPU The CPU consists of �6�1 A control unit that controls all of the computer’s functions and an �6�1 Arithmetic and logical unit (ALU) that performs any calculation Memory Memory holds all programs and What is RAM currently open? Data (notes) Word processor OS Output devices Output devices convert the computer’s electronic signals back into information Secondary storage devices These devices store programs and data The programs and data are not necessarily (or likely to be) in current E DVD CD Communication devices These devices enable a computer to connect to another List the six different type of hardware? Secondary storage(external)， input， processor， output ， memory， C Name eight pieces of hardware USB， keyboard， monitor， screen， RAM， ROM， VDU， M The system unit and peripheral devices The system unit is the computer Peripheral devices are any devices around the outside， or in other words， plugged into the (back of) the Peripheral devices include the key board， mouse， printer， joy stick and Peripheral devices are any devices around the outside， or in other words， plugged into the (back of) the Peripheral devices include the keyboard， mouse， printer， joy stick and What else does a computer have? Software Software is a computer program ，which is a detailed set of instructions that directs a computer to perform the tasks necessary to process data into These instructions are written in languages that computer can Software includes computer games， a word processing packing， an accounting package， amongst Definition of a computer system �6�1 A computer system is the configuration of hardware and software， functioning together， to process data into useful information， in order to achieve a purpose for a human What is data? �6�1 Data is raw facts， be they numbers， words， images and sounds， that can be input into a Mary a name is a piece of data What is information? �6�1 Information is processed data， that has meaning and is John is a list of names who scored an A grade on an exam John A Chai A Pam A Commodore $23 500 Magna $21 500 Falcon $19 800 The system unit contains the �6�1 Motherboard �6�1 CPU �6�1 Memory �6�1 Other electronics It is where the computer program instructions are executed and the data is manipulatedThe Processor CPU The CPU interprets and carries out basic instructions that operate the computer， the CPU contain the �6�1 Control unit and the �6�1 Arithmetic logic unit Control unit The control unit directs and coordinates the computer’s For every single instruction， the control unit repeats four basic operations， �6�1 Fetching �6�1 Decoding �6�1 Executing �6�1 Storing CPU speed The CPU’s speed may be measured in MIPS The number of millions of instructions per second Arithmetic/logic unit The ALU performs all calculations， which involve �6�1 Arithmetic operations 2+3 �6�1 Comparison operations age>=17 �6�1 Logical operations pass Processing instructions A CPU may begin executing a second machine cycle before completing the first-referred to as Current CPU’s can pipeline up to 4 Storage within the CPU Registers temporarily hold data and The computer’s clock A System clock is necessary to control the timing of all computer Each tick of the clock is referred to as a clock Clock speed is the speed at which a processor executes A hertz is one cycle per second and a megahertz is 1024 by1024 and a gigahertz is 1024 by 1024 Memory Memory is the temporary storage place for data and (program) Memory is measured in �6�1 Kilobytes 1024 bytes 2^10 �6�1 Megabytes 1024* 1024 bytes 2^20 �6�1 Gigabytes 1024*1024*1024 bytes 2^30 Representation of data Digital computers are built from many small electronic Each circuit， at any point of time can be turned OFF or ON Hence these devices are called two state Binary Digit 0and 1 Each off or on digital value is called a bit， short for binary A 1 bit computer would be able to distinguish between two values-characters， symbols or Hardly sufficient for the characters on the keyboard Bits Characters 1 2 2 4 3 8 4 16 5 32 6 64 7 128 8 256

Web Application Development Based on ASP and Access Database - Web Design of

计算机专业科技论文免费

提供一份计算机专业本科毕业论文，供写作参考。计算机网络在电子商务中的应用摘要：随着计算机网络技术的飞进发展，电子商务正得到越来越广泛的应用。由于电子商务中的交易行为大多数都是在网上完成的， 因此电子商务的安全性是影响趸易双方成败的一个关键因素。本文从电子商务系统对计算机网络安全，商务交易安全性出发，介绍利用网络安全枝术解决安全问题的方法。关键词：计算机网络，电子商务安全技术一． 引言近几年来．电子商务的发展十分迅速 电子商务可以降低成本．增加贸易机会，简化贸易流通过程，提高生产力，改善物流和金流、商品流．信息流的环境与系统 虽然电子商务发展势头很强，但其贸易额所占整个贸易额的比例仍然很低。影响其发展的首要因素是安全问题．网上的交易是一种非面对面交易，因此“交易安全“在电子商务的发展中十分重要。可以说．没有安全就没有电子商务。电子商务的安全从整体上可分为两大部分．计算机网络安全和商务交易安全。计算机网络安全包括计算机网络设备安全、计算机网络系统安全、数据库安全等。其特征是针对计算机网络本身可能存在的安全问题，实施网络安全增强方案．以保证计算机网络自身的安全性为目标。商务安全则紧紧围绕传统商务在Interne'(上应用时产生的各种安全问题．在计算机网络安全的基础上．如何保障电子商务过程的顺利进行。即实现电子商务的保密性．完整性．可鉴别性．不可伪造性和不可依赖性。二、电子商务网络的安全隐患1窃取信息：由于未采用加密措施．数据信息在网络上以明文形式传送．入侵者在数据包经过的网关或路由器上可以截获传送的信息。通过多次窃取和分析，可以找到信息的规律和格式，进而得到传输信息的内容．造成网上传输信息泄密2．篡改信息：当入侵者掌握了信息的格式和规律后．通过各种技术手段和方法．将网络上传送的信息数据在中途修改 然后再发向目的地。这种方法并不新鲜．在路由器或者网关上都可以做此类工作。3假冒由于掌握了数据的格式，并可以篡改通过的信息，攻击者可以冒充合法用户发送假冒的信息或者主动获取信息，而远端用户通常很难分辨。4恶意破坏：由于攻击者可以接入网络．则可能对网络中的信息进行修改．掌握网上的机要信息．甚至可以潜入网络内部．其后果是非常严重的。三、电子商务交易中应用的网络安全技术为了提高电子商务的安全性．可以采用多种网络安全技术和协议．这些技术和协议各自有一定的使用范围，可以给电子商务交易活动提供不同程度的安全保障。1．防火墙技术。防火墙是目前主要的网络安全设备。防火墙通常使用的安全控制手段主要有包过滤、状态检测、代理服务 由于它假设了网络的边界和服务，对内部的非法访问难以有效地控制。因此．最适合于相对独立的与外部网络互连途径有限、网络服务种类相对集中的单一网络(如常见的企业专用网) 防火墙的隔离技术决定了它在电子商务安全交易中的重要作用。目前．防火墙产品主要分为两大类基于代理服务方式的和基于状态检测方式的。例如Check Poim Fi rewalI-140是基于Unix、WinNT平台上的软件防火墙．属状态检测型 Cisco PIX是硬件防火墙．也属状态检测型。由于它采用了专用的操作系统．因此减少了黑客利用操作系统G)H攻击的可能性：Raptor完全是基于代理技术的软件防火墙 由于互联网的开放性和复杂性．防火墙也有其固有的缺点(1)防火墙不能防范不经由防火墙的攻击。例如．如果允许从受保护网内部不受限制地向外拨号．一些用户可以形成与Interne'(的直接连接．从而绕过防火墙：造成一个潜在的后门攻击渠道，所以应该保证内部网与外部网之间通道的唯一性。(2)防火墙不能防止感染了病毒的软件或文件的传输．这只能在每台主机上装反病毒的实时监控软件。(3)防火墙不能防止数据驱动式攻击。当有些表面看来无害的数据被邮寄或复制到Interne'(主机上并被执行而发起攻击时．就会发生数据驱动攻击．所以对于来历不明的数据要先进行杀毒或者程序编码辨证，以防止带有后门程序。2．数据加密技术。防火墙技术是一种被动的防卫技术．它难以对电子商务活动中不安全的因素进行有效的防卫。因此．要保障电子商务的交易安全．就应当用当代密码技术来助阵。加密技术是电子商务中采取的主要安全措施，贸易方可根据需要在信息交换的阶段使用。目前．加密技术分为两类．即对称加密／对称密钥加密／专用密钥加密和非对称加密／公开密钥加密。现在许多机构运用PKI(punickey nfrastructur)的缩写．即 公开密钥体系”)技术实施构建完整的加密／签名体系．更有效地解决上述难题．论文其他部分请参考下面的网址：

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Web Application Development Based on ASP and Access Database - Web Design of

Information literacy Knowing how to find data from several sources， select relevant material， analyse and organise it into a form that can be used to make Computers have become the tools people use to access and manage Information technologists are people who analyse and design the What is a computer? Tradition definitions of computers include • A machine that accepts data and processes it into use • A computer is a binary， digital， electronic， stored program • While a computer is commonly a digital machine， analogue machine do An electronic device， operating under the control of instructions stored in its own memory unit， that can accept data (input)， process data arithmetically and logically， produce results (output) from the processing and stores results for future Many computers receive and send data (communicate) across networks LAN and W A computer system consists of hardware and What is hardware? Hardware Hardware is physical devices or components that can be physically handled – you can thou Input Devices Input devices convert data that humans collect into coded electrical signals that a computer can The central processing unit The electronic processing takes place in the CPU The CPU consists of • A control unit that controls all of the computer’s functions and an • Arithmetic and logical unit (ALU) that performs any calculation Memory Memory holds all programs and What is RAM currently open? Data (notes) Word processor OS Output devices Output devices convert the computer’s electronic signals back into information Secondary storage devices These devices store programs and data The programs and data are not necessarily (or likely to be) in current E DVD CD Communication devices These devices enable a computer to connect to another List the six different type of hardware? Secondary storage(external)， input， processor， output ， memory， C Name eight pieces of hardware USB， keyboard， monitor， screen， RAM， ROM， VDU， M The system unit and peripheral devices The system unit is the computer Peripheral devices are any devices around the outside， or in other words， plugged into the (back of) the Peripheral devices include the key board， mouse， printer， joy stick and Peripheral devices are any devices around the outside， or in other words， plugged into the (back of) the Peripheral devices include the keyboard， mouse， printer， joy stick and What else does a computer have? Software Software is a computer program ，which is a detailed set of instructions that directs a computer to perform the tasks necessary to process data into These instructions are written in languages that computer can Software includes computer games， a word processing packing， an accounting package， amongst Definition of a computer system • A computer system is the configuration of hardware and software， functioning together， to process data into useful information， in order to achieve a purpose for a human What is data? • Data is raw facts， be they numbers， words， images and sounds， that can be input into a Mary a name is a piece of data What is information? • Information is processed data， that has meaning and is John is a list of names who scored an A grade on an exam John A Chai A Pam A Commodore $23 500 Magna $21 500 Falcon $19 800 The system unit contains the • Motherboard • CPU • Memory • Other electronics It is where the computer program instructions are executed and the data is manipulatedThe Processor CPU The CPU interprets and carries out basic instructions that operate the computer， the CPU contain the • Control unit and the • Arithmetic logic unit Control unit The control unit directs and coordinates the computer’s For every single instruction， the control unit repeats four basic operations， • Fetching • Decoding • Executing • Storing CPU speed The CPU’s speed may be measured in MIPS The number of millions of instructions per second Arithmetic/logic unit The ALU performs all calculations， which involve • Arithmetic operations 2+3 • Comparison operations age>=17 • Logical operations pass Processing instructions A CPU may begin executing a second machine cycle before completing the first-referred to as Current CPU’s can pipeline up to 4 Storage within the CPU Registers temporarily hold data and The computer’s clock A System clock is necessary to control the timing of all computer Each tick of the clock is referred to as a clock Clock speed is the speed at which a processor executes A hertz is one cycle per second and a megahertz is 1024 by1024 and a gigahertz is 1024 by 1024 Memory Memory is the temporary storage place for data and (program) Memory is measured in • Kilobytes 1024 bytes 2^10 • Megabytes 1024* 1024 bytes 2^20 • Gigabytes 1024*1024*1024 bytes 2^30 Representation of data Digital computers are built from many small electronic Each circuit， at any point of time can be turned OFF or ON Hence these devices are called two state Binary Digit 0and 1 Each off or on digital value is called a bit， short for binary A 1 bit computer would be able to distinguish between two values-characters， symbols or Hardly sufficient for the characters on the keyboard Bits Characters 1 2 2 4 3 8 4 16 5 32 6 64 7 128 8 256

Information literacy Knowing how to find data from several sources， select relevant material， analyse and organise it into a form that can be used to make Computers have become the tools people use to access and manage Information technologists are people who analyse and design the What is a computer? Tradition definitions of computers include �6�1 A machine that accepts data and processes it into use �6�1 A computer is a binary， digital， electronic， stored program �6�1 While a computer is commonly a digital machine， analogue machine do An electronic device， operating under the control of instructions stored in its own memory unit， that can accept data (input)， process data arithmetically and logically， produce results (output) from the processing and stores results for future Many computers receive and send data (communicate) across networks LAN and W A computer system consists of hardware and What is hardware? Hardware Hardware is physical devices or components that can be physically handled – you can thou Input Devices Input devices convert data that humans collect into coded electrical signals that a computer can The central processing unit The electronic processing takes place in the CPU The CPU consists of �6�1 A control unit that controls all of the computer’s functions and an �6�1 Arithmetic and logical unit (ALU) that performs any calculation Memory Memory holds all programs and What is RAM currently open? Data (notes) Word processor OS Output devices Output devices convert the computer’s electronic signals back into information Secondary storage devices These devices store programs and data The programs and data are not necessarily (or likely to be) in current E DVD CD Communication devices These devices enable a computer to connect to another List the six different type of hardware? Secondary storage(external)， input， processor， output ， memory， C Name eight pieces of hardware USB， keyboard， monitor， screen， RAM， ROM， VDU， M The system unit and peripheral devices The system unit is the computer Peripheral devices are any devices around the outside， or in other words， plugged into the (back of) the Peripheral devices include the key board， mouse， printer， joy stick and Peripheral devices are any devices around the outside， or in other words， plugged into the (back of) the Peripheral devices include the keyboard， mouse， printer， joy stick and What else does a computer have? Software Software is a computer program ，which is a detailed set of instructions that directs a computer to perform the tasks necessary to process data into These instructions are written in languages that computer can Software includes computer games， a word processing packing， an accounting package， amongst Definition of a computer system �6�1 A computer system is the configuration of hardware and software， functioning together， to process data into useful information， in order to achieve a purpose for a human What is data? �6�1 Data is raw facts， be they numbers， words， images and sounds， that can be input into a Mary a name is a piece of data What is information? �6�1 Information is processed data， that has meaning and is John is a list of names who scored an A grade on an exam John A Chai A Pam A Commodore $23 500 Magna $21 500 Falcon $19 800 The system unit contains the �6�1 Motherboard �6�1 CPU �6�1 Memory �6�1 Other electronics It is where the computer program instructions are executed and the data is manipulatedThe Processor CPU The CPU interprets and carries out basic instructions that operate the computer， the CPU contain the �6�1 Control unit and the �6�1 Arithmetic logic unit Control unit The control unit directs and coordinates the computer’s For every single instruction， the control unit repeats four basic operations， �6�1 Fetching �6�1 Decoding �6�1 Executing �6�1 Storing CPU speed The CPU’s speed may be measured in MIPS The number of millions of instructions per second Arithmetic/logic unit The ALU performs all calculations， which involve �6�1 Arithmetic operations 2+3 �6�1 Comparison operations age>=17 �6�1 Logical operations pass Processing instructions A CPU may begin executing a second machine cycle before completing the first-referred to as Current CPU’s can pipeline up to 4 Storage within the CPU Registers temporarily hold data and The computer’s clock A System clock is necessary to control the timing of all computer Each tick of the clock is referred to as a clock Clock speed is the speed at which a processor executes A hertz is one cycle per second and a megahertz is 1024 by1024 and a gigahertz is 1024 by 1024 Memory Memory is the temporary storage place for data and (program) Memory is measured in �6�1 Kilobytes 1024 bytes 2^10 �6�1 Megabytes 1024* 1024 bytes 2^20 �6�1 Gigabytes 1024*1024*1024 bytes 2^30 Representation of data Digital computers are built from many small electronic Each circuit， at any point of time can be turned OFF or ON Hence these devices are called two state Binary Digit 0and 1 Each off or on digital value is called a bit， short for binary A 1 bit computer would be able to distinguish between two values-characters， symbols or Hardly sufficient for the characters on the keyboard Bits Characters 1 2 2 4 3 8 4 16 5 32 6 64 7 128 8 256

海外英语杂志欢迎投稿，详情见我的空间