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1、《計算機(jī)網(wǎng)絡(luò)基礎(chǔ)》課程報告基于Wireshark的TCP和UDP報文分析院系:班級:學(xué)號:姓名:教師:2012年11月4日9目錄一TCP連接時的三次握手··································3二TCP連接釋放時的四次握手······························5三UDP報文分析··········································73.1UDP報文結(jié)構(gòu)······································73.2UDP檢驗和的計算·····
2、····························7四結(jié)束語···············································99一、TCP連接時的三次握手TCP協(xié)議為終端設(shè)備提供了面向連接的、可靠的網(wǎng)絡(luò)服務(wù)。TCP在交換數(shù)據(jù)報文段之前要在發(fā)送方和接收方之間建立連接。客戶是連接的發(fā)起者,服務(wù)器是被動打開和客戶進(jìn)行聯(lián)系。具體的過程如下所述。第一次握手:客戶發(fā)送SYN=1,seq=0的TCP報文給服務(wù)器Ps:客戶的TCP向服務(wù)器發(fā)出連接請求報文段,其首部中的同步位SYN=1。序號seq=0,表明報文中未攜帶數(shù)據(jù)
3、。報文如下:源端口號:56644(56644)目的端口號:http(80)[Streamindex:0]Sequencenumber:0(relativesequencenumber)Headerlength:32bytesFlags:0x02(SYN)000.........=Reserved:Notset9...0........=Nonce:Notset....0.......=CongestionWindowReduced(CWR):Notset.....0......=ECN-Echo:Notset......0.....=Urg
4、ent:Notset.......0....=Acknowledgement:Notset........0...=Push:Notset.........0..=Reset:Notset..........1.=Syn:Set...........0=Fin:NotsetWindowsize:8192Checksum:0x1030[validationdisabled]Options:(12bytes)第二次握手:服務(wù)器發(fā)送SYN=1,ACK=1,seq=0的TCP報文給客戶Ps:服務(wù)器的TCP收到客戶發(fā)來的連接請求報文段后,如同意,則發(fā)
5、回確認(rèn)。服務(wù)器在確認(rèn)報文段中應(yīng)使SYN=1,使ACK=1。序號seq=0,表明報文中未攜帶數(shù)據(jù)。報文如下:源端口號:http(80)目的端口號:56644(56644)[Streamindex:0]Sequencenumber:0(relativesequencenumber)Acknowledgementnumber:1(relativeacknumber)Headerlength:32bytesFlags:0x12(SYN,ACK)000.........=Reserved:Notset...0........=Nonce:Notset
6、....0.......=CongestionWindowReduced(CWR):Notset.....0......=ECN-Echo:Notset......0.....=Urgent:Notset.......1....=Acknowledgement:Set........0...=Push:Notset.........0..=Reset:Notset..........1.=Syn:Set...........0=Fin:NotsetWindowsize:5840Checksum:0x54f6[validationdisabl
7、ed]Options:(12bytes)第三次握手:客戶發(fā)送ACK=1的TCP報文給服務(wù)器Ps:客戶收到報文段后向服務(wù)器給出確認(rèn),其ACK=1。客戶的TCP通知上層應(yīng)用進(jìn)程,連接已經(jīng)建立。服務(wù)器的TCP收到主機(jī)客戶的確認(rèn)后,也通知其上層應(yīng)用進(jìn)程,TCP連接已經(jīng)建立。9報文如下:源端口號:56644(56644)目的端口號:http(80)[Streamindex:0]Sequencenumber:1(relativesequencenumber)Acknowledgementnumber:1(relativeacknumber)Header
8、length:20bytesFlags:0x10(ACK)000.........=Reserved:Notset...0........=Nonce:Notset....0..