缓冲层的两大攻击

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1、CHAPTER14MitigatingLayer2AttacksUnlikehubs,switchescannotregulatetheflowofdatabetweentheirportsbycreatingalmost“instant”networksthatcontainonlythetwoenddevicescommunicatingwitheachother.Dataframesaresentbyendsystems,andtheirsourceanddestinationaddressesarenotchanged

2、throughouttheswitcheddomain.Switchesmaintaincontent-addressablememory(CAM)lookuptablestotrackthesourceaddresseslocatedontheswitchports.Theselookuptablesarepopulatedbyanaddress-learningprocessontheswitch.Ifthedestinationaddressofaframeisnotknownoriftheframereceivedb

3、ytheswitchisdestinedforabroadcastaddress,theswitchforwardstheframeoutallports.Withtheirabilitytoisolatetrafficandcreatethe“instant”networks,switchescanbeusedtodivideaphysicalnetworkintomultiplelogicalorVLANsthroughtheuseofLayer2trafficsegmentation.VLANsenablenetworka

4、dministratorstodividetheirphysicalnetworksintoasetofsmallerlogicalnetworks.Liketheirphysicalcounterparts,eachVLANconsistsofasinglebroadcastdomainisolatedfromotherVLANsandworkbytaggingpacketswithanidentificationheaderandthenrestrictingtheportsthatthetaggedpacketscanb

5、ereceivedontothosethatarepartoftheVLAN.ThetwomostprevalentVLANtaggingtechniquesaretheIEEE802.1qtagandtheCiscoInter-SwitchLink(ISL)tag.ThischapterdiscussesLayer2attacks,mitigations,bestpractices,andfunctionality.“DoIKnowThisAlready?”QuizThepurposeofthe“DoIKnowThisAl

6、ready?”quizistohelpyoudecidewhetheryoureallyneedtoreadtheentirechapter.Ifyoualreadyintendtoreadtheentirechapter,youdonotnecessarilyneedtoanswerthesequestionsnow.The11-questionquiz,derivedfromthemajorsectionsin“FoundationTopics”sectionofthechapter,helpsyoudetermineh

7、owtospendyourlimitedstudytime.Table14-1outlinesthemajortopicsdiscussedinthischapterandthe“DoIKnowThisAlready?”quizquestionsthatcorrespondtothosetopics.280Chapter14:MitigatingLayer2AttacksTable14-1“DoIKnowThisAlready?”FoundationTopicsSection-to-QuestionMappingFounda

8、tionTopicsSectionQuestionsCoveredinThisSectionTypesofAttacks1–10FactorsAffectingLayer2MitigationTechniques11CAUTIONThegoalofself-assessmentistoga