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1、1Computernetworksandsecurity2OutlineNetworkOverviewDefinitionTheInternetThenandNowNetworkorganizationOSIModelCategoriesofNetworksConnectingDevicesTheInternetandTCP/IPProtocolSecurity3ObjectivesUnderstandtherationalefortheexistenceofnetworks.Distinguishbetweenthethre
2、etypesofnetworks:LANs,MANs,andWANs.UnderstandtheOSImodelandTCP/IP.ListdifferentconnectingdevicesandtheOSIlayersinwhicheachdeviceoperates.Definevirusandexplainhowitworks.Definefouraspectsofsecurityinanetwork:privacy,authentication,integrity,andnonrepudiation.4Datacom
3、municationsDatacommunications,thetechnologythatenablescomputerstocommunicate,isdefinedasthetransmissionoftext,numeric,voiceorvideodatafromonemachinetoanother.5DatacommunicationsTherearethefourcomponentsofdatacommunications:Sender:thecomputerthatissendingthemessage.R
4、eceiver:thecomputerreceivingthemessage.Channel:themediathatcarriesortransportsthemessage.Thiscouldbetelephoneline,coaxialcable,microwavesignal,orfiberoptic.Protocol:therulesthatgoverntheorderlytransferofthedatasent.6UsesofcommunicationsEmailVoicemailFaxVideoconferen
5、cingTelecommutingGlobalPositioningSystem(GPS)SharedResourcesOnlineServicesRefer7TelecommutingTelecommutingisaworkarrangementinwhichemployeesworkawayfromacompany’sstandardworkplace,butcommunicatewiththeofficeusingsomecommunicationstechnology.Atelecommuteroftenworksat
6、homeandconnectstothemainoffice’snetworkusingapersonalcomputerequippedwithcommunicationssoftwareandacommunicationsdevice.8GlobalPositioningSystemAglobalpositioningsystem(GPS)consistsofoneormoreearth-basedreceiversthatacceptandanalyzesignalssentbysatellitesinordertode
7、terminethereceiver’sgeographiclocation.AGPSreceivercanbehandheldormountedonanobjectsuchasanautomobile,boat,airplane,farmandconstructionequipment,oracomputer.AGPSoftenisusedtolocateapersonorobject;ascertainthebestroutebetweentwopoint;monitorthemovementofapersonorobje
8、ct;orcreateamap.9CommunicationschannelCommunicationschannelisthecommunicationspathbetweentwodevices.Acommunicationschanneliscomposedofoneo
