操作系统实验报告 时间片轮转调度算法

“网络协议分析”实验4实验名称：用Ethereal研究DNS和HTTP协议实验目的：通过对捕获分组的分析和研究，加深对DNS协议和HTTP协议的工作原理和实现过程的理解。实验环境：连网PC机，Ethereal网络协议分析软件实验步骤：安装Ethereal网络协议分析器。打开Ethereal软件菜单中的Help->Contents，可学习Ethereal的使用方法。开始捕获分组之前，清空客户端Web浏览器的高速缓存和DNS的高速缓存（命令为：ipconfig/flushdns）。（想一想，为什么？在Capture->Option里选择网卡类型；取消捕获分组的“混杂模式”设置捕获过滤器为：“host本机IP”，这样Ethereal就会只捕获从本机发出的和发往本机的分组。点击Start启动协议分析器，用Ethereal捕获从本机发出和发往本机的分组。在Web浏览器中输入URL（如,等，网页较简单）。网页显示出来后，过一会儿停止捕获。将跟踪文件保存在一个文件中。实验结果分析：1.在跟踪列表框中找出请求网页时发出的DNS查询报文和回答报文，找出发起TCP连接的三次握手报文，找出HTTP请求报文和响应报文。174.518474202.1^6.2.175202.1^6.0.16HTTPGET』HTTP』LI4.5203284.5203544.5894134.604779266675757575DNSTCPTCPTCPstandardquery[MalformedPacker]http>1509[ACK]seq=lAck=288win=[TCPsegmentofareassernbledPDU][TCPsegmentofareassernbledPDU]224.60481675202.196.O.lhTCP1509>http[ACK]seq=238Ack=2921\4.6065264.606702667575TCPTCP75202.196.O.lhTCP264.591558675274.608439675TCPTCP284.608477756TCP4.6085704.593452667575TCPTCP314.59347475202.196.O.lhTCP324.609855675[TCPsegmentofareassembledPDU][TCPsegmentofareassembledPDU]1509[TCPsegmentofareassemb-!edPDU][TCPsegmentofareassembledPDU]1509Ittp[ACK：15pq=238Ack=3761[TCPsegmentofareassernb-!edPDU][TCPsegmentofareassembledPDU]1509>http[ACK]Seq=238Ack=llh01HTTPHTTP/1.1200OK(text/html)2.在协议框中找出各层协议，观察各层协议，并对照教材中DNS查询/回答报文结构和HTTP请求/响应报文结构对这些应用层报文进行分析，找出2.uunid.11iNd.mt±iLem<qut±iyjT「ansactionID:0xc4a6□Flags:0x0100(standard.0000=0....=Questions:1Answerrr.s:0query)Response:Messageisaqueryopcode:standardquery(O'；iTruncated:MessageisnottruncatedRecursiondesired:doqueryrecursivelyz:reserved(O')Non-authenticareddataok：:Non-authenticareddataisunacceptab-!eAuthorityrrs:0Addirionalrrs:0BQueries旦mmi~Li,已:typeA,匚~1日5?inName:Type:A(Hostaddress)Class:INCOx0001)Transactionid:0xc4a6QFlags:0x8580(standard.0000=0000=Questions:1Answerrrs:2queryresponse,noerror')F-esponse:MessageisaresponseOpcode:Standardquery(0~)Authoritafive:serverisanauthorityfordomainTruncated:MessageisnottruncatedRecursiondesired:doqueryrecursivelyRecursionavai1able:servercandorecursivequeriesz:reserved(0)Answerauthenticated:Answer/authorityportionwasnotauthenticReplycode:noerror(口)Authorityrrs:2AdditionalRRs:2EQueries□:typeA,classinName:mai1.zzlj"IType:ACHostaddress^)class:in(0x0001)日HypertextTransrerProtocoI日GET/HTTF'/l.lVXnRequestMethod:getRequesturi:/Requesrversion:http/1.1Accept:^/^\r\nAccept-Language:zh-cn\r\nUEEF—AgEni：:叫匚1云311日./4.口(ciSTipmtibla;匚wind□对§nt5.1;TridEnt/a.口；.NETa.Oi匚；.netAccept-Encoding:gzip,def1ate\r\nHost:\r\nconnecrion:Keep-Alive\r\n\r\n0HypertextTransterProtocoI日HTTP/1.1200OK\r\nRequestversi□n:http/1.1ResponseCode:200server:theproxy/0.5.37\r\nDate:Fri,27May201100:40:15GMT\r\ncontent-Type:text/html;charset=utf-8\r\nTransfer-Encoding:chunk:ed\r\nconnection:keep-alive\r\.nExpires:Thu,01Jan197000:00:00GMT\r\nHTTPchunked「已5口匚|门5已Cache-Control:no-store,no-cache,must-revalidate,max-age=0\r\nftagrna:no-cache\r\ncontent-Language:zh-cN\r\nset-cookie:zm_test=true\r\n\r\n©Line-basedtextdata:rext/htm"l3.你的主机所用的DNSHTTPchunked「已5口匚|门5已DNS请求报文和应答报文的ID号一样吗？是什么？一样，0xc4a6你所请求网站的规范名是什么？DNS服务器对你的域名解析请求在应答中给出了几个可用的IP地址？都是什么？2个，6,7和DNS服务器通信时，你的客户机使用的端口号是多少？DNS服务器使用的端口号是多少？64384,53你所请求Web服务器的IP地址是什么？其域名有几个层次(参看教材127页)？64个如果请求一个存在/不存在的网页，Web服务器分别会应答什么？……等等。请自己在所获取的分组中找到尽可能多的信息。IZJnIilIIL-iIIr：-.t!L-iit!|-juiit:-Datachunk(3846octets^chunksize:3846octetsData(3S46bytesChunkboundary-Datachunk(4096octets^chunksize:4096octetsDataC4096bytesMDatachunk(4030MDatachunk(4030octets^Chunksize:4030octets4.点击statistic下的summary，查看跟踪记录的统计概要。Name:Length:Format:C:\DocumentsandSettingsluseiA^面墙艮文la17679byteslibpcap(tcpdump,Ethereal,etc.)Packetsizelimit:TimeFirstpacket:Lastpacket:Elapsed:65535bytes2011-05-2708:32:372011-05-2708:32:4200:00:05CaptureInterface:Intel(R)82567LM-3GigabitNetworkConnection(Microsoft'sPacketScheduler)FileCapturefilter:host75Droppedpackets:unknownDisplayDisplay