計(jì)算機(jī)網(wǎng)絡(luò)實(shí)驗(yàn)報(bào)告-ICMP

PAGE－PAGE1－陜西師范大學(xué)計(jì)算機(jī)網(wǎng)絡(luò)實(shí)驗(yàn)報(bào)告實(shí)驗(yàn)七ICMP一、實(shí)驗(yàn)?zāi)康?.熟悉并掌握wireshark的操作。2．分析ICMP協(xié)議。二、實(shí)驗(yàn)器材1.PC機(jī)電腦一臺(tái)。2．下載wireshark軟件并安裝三、實(shí)驗(yàn)內(nèi)容及問(wèn)題回答1.ICMPandPing打開(kāi)wireshark開(kāi)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(jī)的IP地址為：3目的主機(jī)的IP地址為：532.WhyisitthatanICMPpacketdoesnothavesourceanddestinationportNumbers答：從課本可知，ICMP用于主機(jī)和路由器彼此交互網(wǎng)絡(luò)層信息。ICMP報(bào)文有一個(gè)類(lèi)型字段和一個(gè)編碼字段，用來(lái)表示特定的消息被接收。因?yàn)樗芙忉屗邢?，所以ICMP到應(yīng)用層不需要端口號(hào)。3.Examineoneofthepingrequestpacketssentbyyourhost.WhataretheICMPtypeandcodenumbers?WhatotherfieldsdoesthisICMPpackethave?Howmanybytesarethechecksum,sequencenumberandidentifierfields?類(lèi)型和編碼字段類(lèi)型和編碼字段ICMP類(lèi)型：8（回顯請(qǐng)求）ICMP編碼：0ICMP報(bào)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(lèi)型和編碼字段類(lèi)型和編碼字段ICMP類(lèi)型：0（回顯回答）ICMP編碼：0ICMP報(bào)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(kāi)wireshark開(kāi)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(jī)IP地址：3目的地主機(jī)IP地址：496.IfICMPsentUDPpacketsinstead(asinUnix/Linux),wouldtheIPprotocolnumberstillbe01fortheprobepackets?Ifnot,whatwoulditbe?答：如果ICMP發(fā)送UDP數(shù)據(jù)報(bào)，IP協(xié)議號(hào)應(yīng)該為0x11.十進(jìn)制為17，表明交給UDP。7.ExaminetheICMPechopacketinyourscreenshot.IsthisdifferentfromtheICMPpingquerypacketsinthefirsthalfofthislab?Ifyes,howso?ICMP請(qǐng)求回顯報(bào)文ICMP請(qǐng)求回顯報(bào)文答：ICMP回顯數(shù)據(jù)報(bào)與ping請(qǐng)求數(shù)據(jù)報(bào)有相同的字段。8.ExaminetheICMPerrorpacketinyourscreenshot.IthasmorefieldsthantheICMPechopacket.Whatisincludedinthosefields?其中的ICMP字段其中的IP字段ICMP錯(cuò)誤數(shù)據(jù)報(bào)其中的ICMP字段其中的IP字段ICMP錯(cuò)誤數(shù)據(jù)報(bào)答：ICMP錯(cuò)誤數(shù)據(jù)報(bào)包括;所有IP字段和原來(lái)的ICMP字段。9.ExaminethelastthreeICMPpacketsreceivedbythesourcehost.HowarethesepacketsdifferentfromtheICMPerrorpackets?Whyaretheydifferent?類(lèi)型碼和編碼都為0類(lèi)型碼和編碼都為0答：最后三個(gè)ICMP數(shù)據(jù)報(bào)類(lèi)型碼都為0，是回顯回答，而不是11（TTL過(guò)期），它不同于錯(cuò)誤報(bào)文段是引文數(shù)據(jù)報(bào)在TTL過(guò)期之前已經(jīng)全部送往目的地。10.Withinthetracertmeasurements,istherealinkwhosedelayissignificantlylongerthanothers?RefertothescreenshotinFigure4,istherealinkwhosedelayissignificantlylongerthanothers?Onthebasisoftherouternames,canyougu