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Computer NetworkFundamentalsPPTCourseware Engli•Introduction•Network Components•Network TopologiesCATALOGUE•Network Protocol目录•Network Security•Conclusion01IntroductionDefinition of Computer NetworkSummaryDetailsThe definitionof acomputer networkis asystem A computer networkis asystem thatinsists ofthatallows multiple computers toconnect andmultiplecomputersconnected throughexchangeinformation communicationchannels Thesecomputers canexchangeinformation,share resources,andperform taskscollaboratively Networks can beclassifiedas localarea networksLANs orwidearea networks WANs,depending on the size andscope of the connectionClassificationof Computer Networks•Summary:Computer networkscan be classified basedon theirsize,scope,and topology•Details:Networks can beclassifiedas localarea networksLANs orwide area networksWANsbased ontheirsizeandscope LANstypically covera smallgeographic area,such as an officeor abuilding,while WANscovera largerarea,such asmultiple buildingsor evenentire countiesNetworkscanalso beclassified basedon their topology,such asstar,ring,mesh,or busnetworksThe Importance ofComputer Networks•Summary:Computer networksplay acritical rolein todayssociety,facility communication,information exchange,and collaboration•Details:Computer networkshave becomean integralpart ofmodern life,connecting peopleacross theglobeand enablingthe exchangeof informationat unexpectedspeeds Networksallow individualsand businessestocollaborate,share dataand resources,and improveproductivity Theyalso facilitatecommunication,allowingpeople tostay connectedwith friendsand familyfar awayIn addition,computer networksare essentialforaccessing andsharing information,making iteasier toaccess thelatest news,research,and educationalresources02Network ComponentsHardwareComponents01Transmission Media02Coaxial cables:used forhigh speedLANs03Twisted paircables:used fortelephone linesandmost commonEthernet cablesHardwareComponents•Fiber opticalcables:used forlongdistance transmissionsand highspeedLANsHardware ComponentsNetworkInterface CardsNICsThese areexpansion cardsthat areinstalled intopersonal computerstoenable themto send and receivedata overa networkHardwareComponents•They containa networkcontrollerthat handlesthephysical layerof theOSImodelHardware ComponentsHubs,Switches,and Hubsare simpledevices Switchesare moreRouters connectdifferentRouters thatconnect multipleadvanced devicesthat networksand forwardnodestogether andlearn thephysical datapackets betweenbroadcastevery messageaddresses of the differentnetworks basedtheyreceive toall otherconnected nodesand onthe destinationIPconnected nodesonly sendmessages toaddressthe destinationnodeSoftware ComponentsNetworkOperating SystemNOSA NOSis asoftware programthat controlsthe basicoperations ofacomputer networkSomeexamples ofNOSs areWindows Server,Linux,and NovellNetworkSoftware ComponentsClientServer SoftwareClientsoftware isresponsible forsending andreceiving data fromother computers onthenetworkServer softwareprovides resources to clientsoftware requests,suchas sharedfiles,printers,or internetconnectivitySoftware ComponentsProtocolSoftware01Protocol softwareis aset ofrules that govern how02computersona networksendandreceive dataSomecommon protocolsare TCP/IP,HTTP,FTP,SMTP,and03POP303Network TopologiesBus Topology在此添加您的文本17字在此添加您的文本16字BusTopology:A lineartopology whereall devicesEasy to expand byadding dropcables to the mainareconnected toa singlecable busand buscommunicationsockets betweendevices onthe bus在此添加您的文本16字在此添加您的文本16字Characteristics Singlepoint of failure:if thebus fails,all devicesaredisconnected在此添加您的文本16字在此添加您的文本16字Simple to install and configure Limiteddistance:Physical lengthofthebus limitsthe number ofdevicesStar TopologyStarTopology:Each deviceis connecteddirectly Characteristicstoa centralhub orswitchEasy to install:each deviceconnects directlyto theCentral pointoffailure:if thehub orswitch fails,central pointall deviceslose connectionEasyto troubleshoot:checking the central pointExpansion islimited bythe numberof portsonreviews allconnected devicesthecentraldeviceRing Topology在此添加您的文本17字在此添加您的文本16字Ring Topology:Devices areconnected ina closedComplex toinstall andconfigureloop,data travelsin onedirection aroundthe ring在此添加您的文本16字在此添加您的文本16字Characteristics Difficulttoexpandwithout disruptingthe ring在此添加您的文本16字在此添加您的文本16字High faulttolerance:if asegment fails,the ringcan Highcost dueto specializedequipment requiredstilloperateMesh TopologyMeshTopology:Each deviceis connectedto Characteristicsmultipleother devices,forming a network ofconnectednodesHigh faulttolerance:multiple pathsbetween Complextoinstalland configuredevicesHighcost dueto cablesand connectionsrequired Scalabilitycanbelimited bythenumberofdevices andconnectionsHybrid TopologyHybridTopology:A combinationoftwo ormore topologies,used toleveragetheir prospectiveadvantagesMayrequire specializedequipment Characteristicsorsoftware supportfor differenttopologiesComplextoinstallandconfigureFlexibility indesign:combinescharacteristics ofdifferenttopologies04Network ProtocolTCP/IP ProtocolSuiteThe TCP/IP protocolsuite is the TCPis aconnection orientedcoreprotocol ofthe Internet,protocol thatprovides reliableconsistingof Transmissiondata transmissionservices,Control ProtocolTCP,Network ensuringthat datais transmittedProtocolIP,and otherauxiliary VSin theorder itis sent.protocols.TCP/IP ProtocolSuiteIP is anetworklayer protocolAuxiliary protocolsinclude Addressresponsiblefor transmittingdatafromResolution ProtocolARP,Reverseone networknode toanother.Address ResolutionProtocol RARP,Dynamic HostConfiguration ProtocolDHCP,etc.HTTP Protocol01Hypertext Transfer Protocol HTTP is aprotocol used totransfer hypertextsuch asweb pages.02HTTPis a statelessprotocol,which meansthat the server willnotmaintain astate forevery request.03HTTP alsosupports arequest/response model,where the clientsends arequest to the serverand theserver returnsa response.04The maincharacteristics ofthe HTTPprotocol includesimplicity,speed,flexibility,connectionlessness,and statelessness.DNS ProtocolThe DNS protocol is used to queryIP addresses输入Domain NameSystem DNSisaservice that02标题and otherrelated informationcorresponding toconvertsdomain namesinto IPaddresses.domain names.0103TheDNSprotocoliscrucial forthe normalDNSservers aredistributed globallyandoperation ofthe Internet,as itallows users to04organized througha hierarchicalstructure,withaccess websitesthrough memorabledomainthe rootserver beingthe top-level server.names.FTP ProtocolFileTransferProtocolFTP isusedtotransfer FTPuses aclient/server architecture,wherefiles overanetwork.the clientinteracts withtheserverthroughFTP commands.FTP supportstwo modes:active modeand TheFTP protocolis widelyused inscenariospassive mode.In activemode,theclientsuch asfile downloading,uploading,andsends datatotheserver;In passivemode,synchronization,and isa commonfilethe serversends datatotheclient.transfer methodontheInternet.05Network SecurityFirewalls•Firewall definition:A firewallisanetwork securitysystem usedtoblock unauthorizedaccess anddata transmission.It canpreventexternal threatsfrom enteringthe internalnetwork whileallowinglegitimate networktraffic topass through.•Firewall types:According totheir workingprinciples andapplication scenarios,firewalls canbe dividedintopacket filteringfirewalls,proxy serverfirewalls,and statefuldetection firewalls.•Firewall deployment:Firewalls areusually deployedat thenetwork entranceasasecurity barrierbetween theinternaland externalnetworks.It canfilter andfilter networktraffic basedon presetsecurity policies.•Limitations offirewalls:Although firewallsare animportant componentof network security,they cannotfullyprevent allnetwork threats.It isnecessary tocombine othersecurity measures,such asintrusion detectionsystems,encryption technologies,etc.,to improvenetwork securityprotection capabilities.Encryption Techniques•Definition of encryption:Encryption isthe processof convertingplaintextinformation intociphertext usinga specificalgorithm toprotectthe confidentialityand integrityof data.Only thosewho holdthecorrect keycan decryptand readthe originaldata.•Common encryptiontypes:According tothe usageof encryptionkeys,encryption canbe dividedintosymmetric encryption and publickey encryption.Symmetric encryptionuses thesame keyfor encryptionanddecryption,while publickey encryptionuses differentkeys forencryptionanddecryption operations.•The applicationof encryptionin networks:In networkcommunication,encryption technologyis widelyused toprotectthe confidentialityof data,such asthe SSL/TLS protocolusedtosecure thetransmission ofonlinetransactions andlogin credentials.•The challengeofencryptiontechnology:With theimprovement ofcomputing powerand thedevelopment ofpasswordanalysis technology,encryption algorithmsneed toconstantly evolveand updateto copewith newthreatsand challenges.Viruses andWords•Definition ofComputer Virus:Acomputervirus isa malicioussoftwareprogram thatcan replicateitself andspread betweencomputers,typically infectingthe systemby attachingto otherprograms orfiles.•The transmissionmode of viruses:viruses canspread throughvarious channelssuch asemail attachments,network sharing,and removablestorage devices.Once infected,the virusmay damagesystem files,stealpersonal information,or causeother damage.•Introduction toWorm Virus:A wormvirus isa typeofvirusthat spreadsindependently ofthe hostprogram.Itspreads byscanning vulnerabilitiesin thenetwork,similar tothe waybacteria inthe biologicalworld reproduce.•Preventive measures:The key to preventingvirus andworm infectionsis totake aseries ofsecurity measures,such asinstalling antivirussoftware,regularly updatingsystem andapplication securitypatches,and notopeningemails andlinks fromunknown sourcesat will.Social EngineeringAttacks•Social engineeringattack definition:Social engineeringattack isa typeofattack thatutilizes theweaknesses ofhuman psychologyand socialbehavior.Attackers obtainsensitive information or manipulatethebehavior ofvictims throughdeception,inducement,and othermeans.•Common socialengineering techniques,such asimpersonation,setting upphishing websites,and creatingemergencysituations,are usedto lurevictims intoleaking personalinformationorperforming maliciousoperations.•Measures toprevent socialengineering attacks:Improving usersecurity awarenessisthekeytopreventingsocial engineering attacks,including educatinguserstoidentify suspiciousinformation andlinks,handlingpersonal privacyinformation withcaution,and nottrusting requestsfrom strangers.•The harmof socialengineeringattacks:Social engineeringattacks oftenbypass technicalprotection measuresbecausethey exploitweaknesses inhuman psychologyand socialbehavior.Therefore,preventing socialengineeringattacks requiresmultiple efforts,including improvingpersonal securityawareness andstrengtheningnetworksecurityeducation.06ConclusionSummary ofthe MainPoints•ImportanceofComputerNetworks:Computer networkshave becomeintegralto business,entertainment,and communication,makingunderstanding theirfundamental principles•Networking Components:The coursecovered theessential componentsof computer networks,including routes,switches,and hubs•Policies andStandards:An overviewofthevarious protocolsand standardsthatgoverncomputernetworkswasprovided•Security Considerations:Important securitymeasures andbest practicesto ensurenetwork integrityand dataprotectionwere discussedFutureTrends inComputerNetworks•5G andBeyond:The evolutionof fifthgeneration5G wirelesstechnologyand itspotential impacton computernetworks,includinghigher datarates andlower latency•Cloud Computing:The increasingtrend ofmoving computingresourcestothe cloud,along withthe associatedchallengesand opportunities•IoT andSmart Devices:The integrationof internetconnected devicesand sensorsinto computernetworks,leading tomore intelligentsystems anddata drivendecision making•AI andMachine Learningin Networks:The potentialfor artificialintelligence AIand machinelearning tooptimizenetwork performance,detect anomalies,and improvesecurityTHANKS感谢观看。