IP实验 41212022 刘佳乐

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1、计算机网络实验报告班级：计算机科学与技术一班姓名：刘佳乐学号：41212022一．实验目的：1.利用wireshark分析IP协议，学习了解IP数据包。2.学习IP报文段的各领域。二．实验器材：1.接入Internet的计算机主机；2.抓包工具wireshark三.实验内容：1.SelectthefirstICMPEchoRequestmessagesentbyyourcomputer,andexpandtheInternetProtocolpartofthepacketinthepacketdetailswindow.WhatistheIPaddress

2、ofyourcomputer?Answer:MycomputerIPaddressis10.136.98.148.2.WithintheIPpacketheader,whatisthevalueintheupperlayerprotocolfield?答：在IP包头部，上层协议区域的值是1。3.HowmanybytesareintheIPheader?HowmanybytesareinthepayloadoftheIPdatagram?Explainhowyoudeterminedthenumberofpayloadbytes.答：IP头部有20个字节，I

3、P数据包的有效载荷是56-20=36个字节。4.HasthisIPdatagrambeenfragmented?Explainhowyoudeterminedwhetherornotthedatagramhasbeenfragmented.答：没有分片，因为Flags和Fragmentoffset都为0。Next,sortthetracedpacketsaccordingtoIPsourceaddressbyclickingontheSourcecolumnheader;asmalldownwardpointingarrowshouldappearnext

4、tothewordSource.Ifthearrowpointsup,clickontheSourcecolumnheaderagain.SelectthefirstICMPEchoRequestmessagesentbyyourcomputer,andexpandtheInternetProtocolportioninthe“detailsofselectedpacketheader”window.Inthe“listingofcapturedpackets”window,youshouldseeallofthesubsequentICMPmessage

5、s(perhapswithadditionalinterspersedpacketssentbyotherprotocolsrunningonyourcomputer)belowthisfirstICMP.UsethedownarrowtomovethroughtheICMPmessagessentbyyourcomputer.5.WhichfieldsintheIPdatagramalwayschangefromonedatagramtothenextwithinthisseriesofICMPmessagessentbyyourcomputer?答：T

6、TL，首部检验和，标识等一直在不断变化。6.Whichfieldsstayconstant?Whichofthefieldsmuststayconstant?Whichfieldsmustchange?Why?答:不变的有：版本号、首部长度、服务类型、标志、偏移、上层协议，源目的和IP地址。必须保持不变的是：版本号、源目的和IP地址必须改变的是：标识和首部检验和。7.DescribethepatternyouseeinthevaluesintheIdentificationfieldoftheIPdatagramNext(withthepacketssti

7、llsortedbysourceaddress)findtheseriesofICMPTTL-exceededrepliessenttoyourcomputerbythenearest(firsthop)router.答：每一个IP数据报头部的标识号都不一样，每次加1。eg:8.WhatisthevalueintheIdentificationfieldandtheTTLfield?答：.Identification字段值为0，TTL字段的值是255。9.DothesevaluesremainunchangedforalloftheICMPTTL-exce

8、ededrepliessenttoyourcomputerbyth