计算机网络实验报告-实验五 探索TCP协议.doc

1陕西师范大学计算机网络实验报告实验五探索TCP协议一、实验目的1.熟悉并掌握wireshark的操作。2.通过实验分析并掌握TCP是如何进行数据传输的，及其如何实现拥塞控制、流量控制等二、实验器材1.PC机电脑一台。2下载wireshark软件并安装三、实验内容通过实验分析并掌握TCP是如何进行数据传输的，及其如何实现拥塞控制、流量控制等四、问题回答1.CapturingabulkTCPtransferfromyourcomputertoaremoteServerGothe/wiresharklabs/alice.txtandretrieveanASCIIcopyofAliceinWonderland.Storethisfile.somewhereonmycomputer.Nextgoto/wireshark-labs/TCP-wireshark-file1.html.ThenIcanseeascreenthatlookslike:2,startupWiresharkandbeginpacketcapture.Returningtobrowser,pressthe“Uploadalice.txtfile”server.StopWiresharkpacketcapture.TheWiresharkwindowlikethis:ThenopeningtheWiresharkcapturedpacketfiletcpethereal-trace-1in/wireshark-labs/wireshark-traces.zip32.Afirstlookatthecapturedtrace1.WhatistheIPaddressandTCPportnumberusedbytheclientcomputer(source)?Toanswerthisquestion,itsprobablyeasiesttoselectanHTTPmessageandexplorethedetailsoftheTCPpacketusedtocarrythisHTTPmessage,usingthe“detailsoftheselectedpacketheaderwindow”(refertoFigure2inthe“GettingStartedwithWireshark”LabifyoureuncertainabouttheWiresharkwindows).答：clientcomputer(source)：IPaddress：02ipaddressTcpportnumber4TCPportnumber：11612.WhatistheIP?OnwhatportnumberisitsendingandreceivingTCPsegmentsforthisconnection?答：theIP：IPaddress：2portnumber：803.Ifyouhavebeenabletocreateyourowntrace,answerthefollowingquestion:WhatistheIPaddressandTCPportnumberusedbyyourclientcomputer(source)?ipaddress:portnumber5答：Myclientcomputer:IPaddress:0ipaddress:TcpportnumberThenWiresharkdothis,selectAnalyze-EnabledProtocols.ThenunchecktheHTTPboxandselectOK.nowseeanWiresharkwindowthatlookslike:63.TCPBasicsAnswerthefollowingquestions；4.WhatisthesequencenumberoftheTCPSYNsegmentthatisusedtoinitiatetheTCP?WhatisitinthesegmentthatidentifiesthesegmentasaSYNsegment?答：sequencenumber:0；syn被设置为1说明是syn段。SequencenumberSynis175.WhatisthesequencenumberoftheSYNACKtotheclientcomputerinreplytotheSYN?WhatisthevalueoftheACKnowledgementfieldintheSYNACKsegment?Hdeterminethatvalue?WhatisitinthesegmentthatidentifiesthesegmentasaSYNACKsegment?答：ThesequencenumberoftheSYNACKis:0；SYNACKsegment中ACKnowledgement的值为1；ACKnowledgementnumber的值为SYN消息中sequencenumber加上1所得；SYN和Acknowledgementf都置为1说明这是一个SYNACKsegment.6.WhatisthesequencenumberoftheTCPsegmentcontainingtheHTTPPOSTcommand?NotethatinordertofindthePOSTcommand,youllneedtodigintothepack