計算機網(wǎng)絡實驗報告-ICMP

PAGE－PAGE1－陜西師范大學計算機網(wǎng)絡實驗報告實驗七ICMP一、實驗目的1.熟悉并掌握wireshark的操作。2．分析ICMP協(xié)議。二、實驗器材1.PC機電腦一臺。2．下載wireshark軟件并安裝三、實驗內(nèi)容及問題回答1.ICMPandPing打開wireshark開始抓包在widows命令下輸入ping–n10www.ust.hk待ping程序終止，停止wireshark抓包1.WhatistheIPaddressofyourhost?WhatistheIPaddressofthedestinationhost?源和目的IP地址。源和目的IP地址。我的主機的IP地址為：3目的主機的IP地址為：532.WhyisitthatanICMPpacketdoesnothavesourceanddestinationportNumbers答：從課本可知，ICMP用于主機和路由器彼此交互網(wǎng)絡層信息。ICMP報文有一個類型字段和一個編碼字段，用來表示特定的消息被接收。因為它能解釋所有消息，所以ICMP到應用層不需要端口號。3.Examineoneofthepingrequestpacketssentbyyourhost.WhataretheICMPtypeandcodenumbers?WhatotherfieldsdoesthisICMPpackethave?Howmanybytesarethechecksum,sequencenumberandidentifierfields?類型和編碼字段類型和編碼字段ICMP類型：8（回顯請求）ICMP編碼：0ICMP報文其他字段包括：checksum(2字節(jié))、identifier（2字節(jié)）、sequencenumber（2字節(jié)）、sequencenumber(LE)、datafields.4.Examinethecorrespondingpingreplypacket.WhataretheICMPtypeandcodenumbers?WhatotherfieldsdoesthisICMPpackethave?Howmanybytesarethechecksum,sequencenumberandidentifierfields?類型和編碼字段類型和編碼字段ICMP類型：0（回顯回答）ICMP編碼：0ICMP報文其他字段包括：checksum(2字節(jié))、identifier（2字節(jié)）、sequencenumber（2字節(jié)）、sequencenumber(LE)、datafields.2.ICMPandTraceroute1.打開wireshark開始抓包2.在widows命令下輸入tracertwww.inria.fr3.待tracert程序終止，停止wireshark抓包截圖如下：5.WhatistheIPaddressofyourhost?WhatistheIPaddressofthetargetdestinationhost?答：我的主機IP地址：3目的地主機IP地址：496.IfICMPsentUDPpacketsinstead(asinUnix/Linux),wouldtheIPprotocolnumberstillbe01fortheprobepackets?Ifnot,whatwoulditbe?答：如果ICMP發(fā)送UDP數(shù)據(jù)報，IP協(xié)議號應該為0x11.十進制為17，表明交給UDP。7.ExaminetheICMPechopacketinyourscreenshot.IsthisdifferentfromtheICMPpingquerypacketsinthefirsthalfofthislab?Ifyes,howso?ICMP請求回顯報文ICMP請求回顯報文答：ICMP回顯數(shù)據(jù)報與ping請求數(shù)據(jù)報有相同的字段。8.ExaminetheICMPerrorpacketinyourscreenshot.IthasmorefieldsthantheICMPechopacket.Whatisincludedinthosefields?其中的ICMP字段其中的IP字段ICMP錯誤數(shù)據(jù)報其中的ICMP字段其中的IP字段ICMP錯誤數(shù)據(jù)報答：ICMP錯誤數(shù)據(jù)報包括;所有IP字段和原來的ICMP字段。9.ExaminethelastthreeICMPpacketsreceivedbythesourcehost.HowarethesepacketsdifferentfromtheICMPerrorpackets?Whyaretheydifferent?類型碼和編碼都為0類型碼和編碼都為0答：最后三個ICMP數(shù)據(jù)報類型碼都為0，是回顯回答，而不是11（TTL過期），它不同于錯誤報文段是引文數(shù)據(jù)報在TTL過期之前已經(jīng)全部送往目的地。10.Withinthetracertmeasurements,istherealinkwhosedelayissignificantlylongerthanothers?RefertothescreenshotinFigure4,istherealinkwhosedelayissignificantlylongerthanothers?Onthebasisoftherouternames,canyougu