Chapter2TCP/IP協(xié)議1.5TCP／／IP協(xié)議基礎(chǔ)礎(chǔ)互聯(lián)網(wǎng)協(xié)協(xié)議（IP）和傳輸控控制協(xié)議議（TCP））是互聯(lián)網(wǎng)網(wǎng)協(xié)議族族中最為為有名的的兩個(gè)協(xié)協(xié)議，其其應(yīng)用非非常廣泛泛，它能能夠用于于任何相相互連接接的計(jì)算算機(jī)網(wǎng)絡(luò)絡(luò)系統(tǒng)之之間的通通信，對(duì)對(duì)局域網(wǎng)網(wǎng)（LAN））和廣域網(wǎng)網(wǎng)（WAN））都有非常常好的效效果。1.5TCP／／IP協(xié)議基礎(chǔ)礎(chǔ)1.5..1TCP／／IP與OSI參考模型型●TCP//IP協(xié)議和OSI模型的對(duì)對(duì)應(yīng)關(guān)系系TCP／IP協(xié)議OSI模型FTP,TELNET,SMTP,RPC,SNMP,DNS,TFTP,BOOTP,HTTP應(yīng)用層TCP,UDP傳輸層IP(ICMP,IGMP),(ARP,RARP)網(wǎng)絡(luò)層1.5TCP／／IP協(xié)議基礎(chǔ)礎(chǔ)●TCP//IP的主要協(xié)協(xié)議之間間的相關(guān)關(guān)性圖中每個(gè)個(gè)封閉的的多邊形形對(duì)應(yīng)了了一個(gè)協(xié)協(xié)議，并并且位于于它所直直接使用用的協(xié)議議之上。。如SMTP依賴于TCP，，而TCP依賴于IP。1.5TCP／／IP協(xié)議基礎(chǔ)礎(chǔ)●TCP/IP的層次結(jié)結(jié)構(gòu)l．應(yīng)用層。。向用戶提提供一組組常用的的應(yīng)用程程序。2．傳輸層（（TCP和UDP））。提供應(yīng)用用程序間間的通信信，提供供了可靠靠的傳輸輸（UDP不能提供供可靠的的傳輸））等。3．網(wǎng)絡(luò)絡(luò)層（IP）。。負(fù)責(zé)數(shù)據(jù)據(jù)包的尋尋徑功能能，以保保證數(shù)據(jù)據(jù)包可靠靠到達(dá)目目標(biāo)主機(jī)機(jī)，若不不能到達(dá)達(dá)，則向向源主機(jī)機(jī)發(fā)送差差錯(cuò)控制制報(bào)文。。4．網(wǎng)絡(luò)絡(luò)接口層層。這是TCP／／IP軟件的最最低層，，負(fù)責(zé)接接收IP數(shù)據(jù)包并并通過(guò)網(wǎng)網(wǎng)絡(luò)發(fā)送送之，或或者從網(wǎng)網(wǎng)絡(luò)上接接收物理理幀，抽抽出IP數(shù)據(jù)包，，并把它它交給IP層。1.5TCP／／IP協(xié)議基礎(chǔ)礎(chǔ)1.5..2網(wǎng)網(wǎng)絡(luò)層（（IP層）將所有的的低層的的物理實(shí)實(shí)現(xiàn)隱藏藏起來(lái)，，作用是是將數(shù)據(jù)據(jù)包從源源主機(jī)發(fā)發(fā)送出去去，并且且使這些些數(shù)據(jù)包包獨(dú)立地地到達(dá)目目的主機(jī)機(jī)。在數(shù)據(jù)包包傳送過(guò)過(guò)程中，，即使是是連續(xù)的的數(shù)據(jù)包包，也可可能走過(guò)過(guò)不同的的路徑，，到達(dá)目目的主機(jī)機(jī)的順序序也會(huì)不不同于它它們被發(fā)發(fā)送時(shí)的的順序。。

1.5TCP／／IP協(xié)議基礎(chǔ)礎(chǔ)●TCP//IP數(shù)據(jù)流程程1.5TCP／／IP協(xié)議基礎(chǔ)礎(chǔ)●IP數(shù)據(jù)包一個(gè)IP數(shù)據(jù)包由由包頭和和數(shù)據(jù)體體兩部分分組成。。包頭由由20字字節(jié)的固固定部分分和變長(zhǎng)長(zhǎng)的可選選項(xiàng)成。。1.5TCP／／IP協(xié)議基礎(chǔ)礎(chǔ)●IP地址在Internet中，每一一臺(tái)主機(jī)機(jī)都有一一個(gè)唯一一的地址址，網(wǎng)關(guān)關(guān)常常有有不止一一個(gè)的地地址。地地址由兩兩部分組組成：網(wǎng)網(wǎng)絡(luò)號(hào)和和主機(jī)號(hào)號(hào)。這種種組合是是唯一的的，以使使每一個(gè)個(gè)IP地址表示示Internet中的唯——一臺(tái)主主機(jī)。所所有IP地址都是是32位位長(zhǎng)。IP地址分為為五類，，平常使使用的是是A，B，，C三類地址址地址類型地址形式AN.H.H.HBN.N.H.HCN.N.N.H1.5TCP／／IP協(xié)議基礎(chǔ)礎(chǔ)●IP層的其它它一些協(xié)協(xié)議ICMP（Internet控制信息息協(xié)議））用來(lái)傳傳送一些些關(guān)于網(wǎng)網(wǎng)絡(luò)和主主機(jī)的控控制信息息。如目目標(biāo)主機(jī)機(jī)是不可可到達(dá)的的、路由由的重定定向等。。ARP（（地址解析析協(xié)議））用來(lái)將將IP地址映射射成相應(yīng)應(yīng)的主機(jī)機(jī)MAC地址。RARP（反向地址址解析協(xié)協(xié)議）用用來(lái)將物物理地址址映射成成32位位的IP地址。1.5TCP／／IP協(xié)議基礎(chǔ)礎(chǔ)1.5..3傳傳輸層（（TCP和UDP））●TCPTCP協(xié)議，即即傳輸控控制協(xié)議議，是一一個(gè)可靠靠的、面面向連接接的協(xié)議議。它允允許在Internet上兩臺(tái)主主機(jī)間信信息的無(wú)無(wú)差錯(cuò)傳傳輸?！馯DP無(wú)連接方方式，即即UDP方式，當(dāng)當(dāng)源主機(jī)機(jī)有數(shù)據(jù)據(jù)時(shí)，就就發(fā)送。。它不管管發(fā)送的的數(shù)據(jù)包包是否到到達(dá)目標(biāo)標(biāo)主機(jī)，，數(shù)據(jù)包包是否出出錯(cuò)，收收到數(shù)據(jù)據(jù)包的主主機(jī)也不不會(huì)告訴訴發(fā)送方方是否正正確收到到了數(shù)據(jù)據(jù)，因此此，這是是一種不不可靠的的數(shù)據(jù)傳傳輸方式式。1.5TCP／／IP協(xié)議基礎(chǔ)礎(chǔ)EarlyprotocolsuiteUniversalIntroductiontoTCP/IPHostInternetTCP//IPHostTCP//IP協(xié)議棧7654325432ApplicationPresentationSessionTransportNetworkDataLinkPhysical1ApplicationTransportInternetDataLinkPhysical1應(yīng)用層Overview*UsedbytherouterApplicationTransportInternetDataLinkPhysicalFileTransfer-TFTP**-FTP**-NFSE-Mail-SMTPRemoteLogin-Telnet**-rlogin**NetworkManagement-SNMP**NameManagement-DNS*傳輸層OverviewTransmissionControlProtocol((TCP)UserDatagramProtocol((UDP)ApplicationTransportInternetDataLinkPhysical面向連接接、可靠靠的無(wú)連接，，不可靠靠的TCP傳輸控制制協(xié)議面向連接接的先建立連連接，后后傳數(shù)據(jù)據(jù)通過(guò)三次次握手建建立連接接可靠的發(fā)送數(shù)據(jù)據(jù)后，必必須等待待確認(rèn)后后才繼續(xù)續(xù)發(fā)送等不到確確認(rèn)，會(huì)會(huì)重傳數(shù)數(shù)據(jù)電話TCPSegmentFormatSourceport((16))Destinationport(16)Sequencenumber((32)Headerlength((4))Acknowledgementnumber(32)Reserved((6)Codebits((6))Window((16)Checksum((16))Urgent((16)Options(0or32ifany)Data(varies))20BytesBit0Bit15Bit16Bit31PortNumbersTCPPortNumbersFTPTransportLayerTELNETDNSSNMPTFTPSMTPUDPApplicationLayer2123255369161RIP520TCPPortNumbersSourcePortDest.Port…HostA102823…SPDPHostZTelnetZDest.port=23..SendpackettomyTelnetapplication.SendSYN(seq=100ctl==SYN)SYNreceivedHostAHostBTCP三次握手手1SendSYN(seq=100ctl==SYN)SYNreceivedSendSYN,ACK(seq=300ack==101ctl=syn,,ack)HostAHostBSYNreceived12TCPThreeWayHandshake/OpenConnectionSendSYN(seq=100ctl==SYN)SYNreceivedSendSYN,ACK(seq=300ack==101ctl=syn,,ack)Established(seq=101ack==301ctl=ack))HostAHostB123SYNreceivedTCPThreeWayHandshake/OpenConnectionTCPSimpleAcknowledgmentWindowsize==1SenderReceiverTCPSimpleAcknowledgmentWindowsize==1SenderReceiverSend1Receive1TCPSimpleAcknowledgmentWindowsize==1SenderReceiverSend1Receive1ReceiveACK2SendACK2TCPSimpleAcknowledgmentWindowsize==1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2TCPSimpleAcknowledgmentWindowsize==1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3TCPSimpleAcknowledgmentWindowsize==1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3Send3Receive3Windowsize==1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3Send3Receive3ReceiveACK4SendACK4TCPSimpleAcknowledgmentTCPSequenceandAcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#SourceDest.Seq..Ack..102823101Ijustsent#10.TCPSequenceandAcknowledgmentNumbersIjustgot#10,nowIneed#11.SourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.10Seq..1Ack..102823SourceDest.11Seq..1Ack..Ijustsent#10.TCPSequenceandAcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.11Seq..2Ack..102823SourceDest.10Seq..1Ack..102823SourceDest.11Seq..1Ack..Ijustgot#10,nowIneed#11.Ijustsent#11.TCPSequenceandAcknowledgmentNumbersSourcePortDest.Port…Sequence#Acknowledgement#102823SourceDest.11Seq..2Ack..102823SourceDest.10Seq..1Ack..102823SourceDest.11Seq..1Ack..102823SourceDest.12Seq..2Ack..Ijustgot#11,nowIneed#12.Ijustsent#11.TCPWindowingSenderReceiverTCPWindowingWindowsize==3Send2SenderReceiverWindowsize==3Send1Windowsize==3Send3Windowsize==3Send2TCPWindowingSenderWindowsize==3Send1Windowsize==3Send3ACK3Windowsize==2Packet3isDroppedReceiverWindowsize==3Send2TCPWindowingSenderWindowsize==3Send1Windowsize==3Send3ACK3Windowsize==2Packet3isDroppedWindowsize==3Send4Windowsize==3Send3ReceiverWindowsize==3Send2TCPWindowingSenderWindowsize==3Send1Windowsize==3Send3ACK3Windowsize==2Packet3isDroppedWindowsize==3Send4Windowsize==3Send3ACK5Windowsize==2ReceiverUDP用戶數(shù)據(jù)據(jù)報(bào)協(xié)議議面向無(wú)連連接發(fā)送數(shù)據(jù)據(jù)之前不不需要建建立連接接直接發(fā)送送不可靠沒(méi)有發(fā)送送確認(rèn)沒(méi)有重傳傳機(jī)制（（由上層層協(xié)議控控制糾錯(cuò)錯(cuò)重傳））Segment尺寸小，，發(fā)送速速度快傳呼，短信NosequenceoracknowledgmentfieldsUDPSegmentFormatSourceport((16))Destinationport(16)Length((16)Data(ifany))1Bit0Bit15Bit16Bit31Checksum((16))8Bytes網(wǎng)絡(luò)層（（IP）OverviewOSI網(wǎng)絡(luò)層對(duì)對(duì)應(yīng)TCP//IPinternet層InternetProtocol((IP))InternetControlMessageProtocol((ICMP)AddressResolutionProtocol((ARP)ReverseAddressResolutionProtocol(RARP)ApplicationTransportInternetDataLinkPhysicalIP層的主要要協(xié)議IP協(xié)議-------InternetProtocol控制數(shù)據(jù)據(jù)的路由由與轉(zhuǎn)發(fā)發(fā)ICMP協(xié)議-----Internet控制消息息協(xié)議測(cè)試網(wǎng)絡(luò)絡(luò)連通性性的協(xié)議議，返回回目的不不可到達(dá)達(dá)、Echo、超時(shí)等消消息Ping，Trcert，PathpingARP協(xié)議-----地地址解析析協(xié)議RARP協(xié)議-----反反向地址址解析協(xié)協(xié)議IPDatagramVersion(4)DestinationIPAddress(32)Options(0or32ifany)Data(variesifany)1Bit0Bit15Bit16Bit31HeaderLength((4))Priority&&TypeofService(8)TotalLength((16)Identification((16))Flags(3)Fragmentoffset((13)Timetolive((8))Protocol((8)Headerchecksum((16)SourceIPAddress((32))20BytesDeterminesdestinationupper-layerprotocolProtocolFieldTransportLayerInternetLayerTCPUDPProtocolNumbersIP176InternetControlMessageProtocolApplicationTransportInternetDataLinkPhysicalDestinationUnreachableEcho(Ping)OtherICMP1AddressResolutionProtocol172..16..3.1172..16..3.2IP:172.16.3..2==????IneedtheEthernetaddressof176.16.3..2.AddressResolutionProtocol172..16..3.1172..16..3.2IP:172.16.3..2==????Iheardthatbroadcast.Themessageisforme.HereismyEthernetaddress.IneedtheEthernetaddressof.AddressResolutionProtocol172..16..3.1IP:172.16.3..2Ethernet:0800.0020.1111172..16..3.2IP:172.16.3..2==????Iheardthatbroadcast.Themessageisforme.HereismyEthernetaddress.IneedtheEthernetaddressof.AddressResolutionProtocolMapIPEthernetLocalARP172..16..3.1IP:172.16.3..2Ethernet:0800.0020.1111172..16..3.2IP:172.16.3..2==????Iheardthatbroadcast.Themessageisforme.HereismyEthernetaddress.IneedtheEthernetaddressof.ReverseARPEthernet:0800.0020.1111IP==????WhatismyIPaddress??ReverseARPEthernet:0800.0020.1111IP==????WhatismyIPaddress??Iheardthatbroadcast.YourIPaddressis172.16.3..25..ReverseARPEthernet:0800.0020.1111IP:172.16.3..25Ethernet:0800.0020.1111IP==????WhatismyIPaddress??Iheardthatbroadcast.YourIPaddressis172.16.3..25..ReverseARPMapEthernetIPEthernet:0800.0020.1111IP:172.16.3..25Ethernet:0800.0020.1111IP==????WhatismyIPaddress??Iheardthatbroadcast.YourIPaddressis172.16.3..25..網(wǎng)絡(luò)中唯唯一路由選擇擇的依據(jù)據(jù)LocationisrepresentedbyanaddressIP地址172..18..0.2172..18..0.1172..17..0.2172..17..0.1172..16..0.2172..16..0.1SADAHDRDATA192..168.1..0192..168.1..1IPAddressing255255255255DottedDecimalMaximumNetworkHost32bitsIPAddressing255255255255DottedDecimalMaximumNetworkHost128643216842111111111111111111111111111111111Binary32bits1891617242532128643216842112864321684211286432168421IPAddressing255255255255DottedDecimalMaximumNetworkHost12864321684211111111111111111111111111111111110101100000100000111101011001100Binary32bits172

16122204ExampleDecimalExampleBinary1891617242532128643216842112864321684211286432168421ClassA:ClassB:ClassC:ClassD:MulticastClassE:ResearchIPAddressClassesNetworkHostHostHostNetworkNetworkHostHostNetworkNetworkNetworkHost8bits8bits8bits8bitsIPAddressClasses1ClassA:Bits:0NNNNNNNHostHostHost891617242532Range((1-126))1ClassB:Bits:10NNNNNNNetworkHostHost891617242532Range((128-191)1ClassC:Bits:110NNNNNNetworkNetworkHost891617242532Range((192-223)1ClassD:Bits:1110MMMMMulticastGroupMulticastGroupMulticastGroup891617242532Range((224-239)HostAddresses172..16..2.1172..16..3.10172..16..12..1210.1.1..110.250..8.1110.180..30..118E1172..161212NetworkHost..NetworkInterface172..16..0.010.0.0..0E0E1RoutingTable172..16..2.1E011111111DeterminingAvailableHostAddresses17216001010110000010000000000000000000016151413121110987654321NetworkHost000000000000000111111111111111111111111111111110......000000000000001111111101123655346553565536-...265534N2N-2=216-2==65534IPAddressClassesExerciseAddressClassNetworkHost10.2.1..1128..63..2.100201..222.5..64192..6.141..2130..113.64.16256..241.201.10IPAddressClassesExerciseAnswersAddressClassNetworkHost10.2.1..1128..63..2.100201..222.5..64192..6.141..2130..113.64.16256..241.201.10ABCCBNonexistent10.0.0..0128..63..0.0201..222.5..0192..6.141..0130..113.0..00.2..1.10.0..2.1000.0..0.640.0..0.20.0..64..16Network172..16..0.0AddressingwithoutSubnets172..16..0.1172..16..0.2172..16..0.3…....172..16..255.253172..16..255.254NetworkAddressingwithSubnets172..16..1.0172..16..2.0172..16..3.0172..16..4.0SubnetAddressing172..16..2.200172..16..2.2172..16..2.160172..16..2.1172..16..3.5172..16..3.100172..16..3.150E0172..16NetworkNetworkInterface172..16..0.0172..16..0.0E0E1NewRoutingTable2160Host..172..16..3.1E1SubnetAddressing172..16..2.200172..16..2.2172..16..2.160172..16..2.1172..16..3.5172..16..3.100172..16..3.150172..16..3.1E0E1172..162160NetworkHost..NetworkInterface172..16..2.0172..16..3.0E0E1NewRoutingTableSubnetSubnetMask1721600255255002552552550IPAddressDefaultSubnetMask8-bitSubnetMaskNetworkHostNetworkHostNetworkSubnetHostAlsowrittenas““/16”where16representsthenumberof1sinthemask.Alsowrittenas““/24”where24representsthenumberof1sinthemask.11111111111111110000000000000000DecimalEquivalentsofBitPatterns1 000 000 0==1281 100 000 0==1921 110 000 0==2241 111 000 0==2401 111 100 0==2481 111 110 0==2521 111 111 0==2541 111 111 1==2551286432168 42116NetworkHost17200101011001111111110101100000100001111111100010000000000000000000010100000000000000000000000000010SubnetMaskwithoutSubnets172..16..2.160255..255.0..0NetworkNumberSubnetsnotinuse——thedefaultNetworknumberextendedbyeightbitsSubnetMaskwithSubnets16NetworkHost172..16..2.160255..255.255.017220101011001111111110101100000100001111111100010000111111110000001010100000000000000000000000000010SubnetNetworkNumber128192224240248252254255SubnetMaskwithSubnets((cont..)NetworkHost172..16..2.160255..255.255.192101011001111111110101100000100001111111100010000111111110000001010100000110000001000000000000010SubnetNetworknumberextendedbytenbits161722128NetworkNumber128192224240248252254255128192224240248252254255SubnetMaskExerciseAddressSubnetMaskClassSubnet172..16..2.1002255..255.255.0255..255.240.0255..255.255.0SubnetMaskExerciseAnswersAddressSubnetMaskClassSubnet172..16..2.1002255..255.255.0255..255.240.0255..255.255.0BAA172..16..2.0BroadcastAddresses172..16..1.0172..16..2.0172..16..3.0172..16..4.0172..16..3.255(Directedbroadcast))255..255.255.255(Localnetworkbroadcast)X172..16..255.255(Allsubnetsbroadcast))AddressingSummaryExample16172216010101100000100001010000000000010HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.19241AddressingSummaryExample1010110011111111000100001111111111111111101000001100000000000010HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.19212161722160AddressingSummaryExample1010110011111111000100001111111111111111101000001100000000000010HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.1921237161722160AddressingSummaryExample101011001111111100010000111111111111111110100000110000001000000000000010HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.1921234161722160AddressingSummaryExample10101100111111110001000011111111111111111010000011000000100000000000001010111111HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.192123456161722160AddressingSummaryExample1010110011111111000100001111111111111111101000001100000010000000000000101011111110000001HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.192123456161722160AddressingSummaryExample101011001111111100010000111111111111111110100000110000001000000000000010101111111000000110111110HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.1921234567161722160AddressingSummaryExample101011001111111110101100000100001111111100010000111111110000001010100000110000001000000000000010101011000001000000000010101111111010110000010000000000101000000110101100000100000000001010111110HostMaskSubnetBroadcastLastFirst172..16..2.160255..255.255.19212345678161722160AddressingSummaryExample101011001111111110101100000100001111111100010000111111110000001010100000110000001000000000000010101011000001000000000010101111111010110000010000000000101000000110101100000100000000001010111110HostMaskSubnetBroadcastLas