网络安全lec0

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1、NetworkSecurity（网络安全原理与技术）Instructor:DiWu（吴迪）SunYat-SenUniversityIntroduction1QuestionComputerSecurityDifference?NetworkSecuritySunYat-SenUniversityIntroduction2AnswerComputerSecurityProtectdataitself.EspeciallyforasharedcomputersystemNetworkSecurityProtectda

2、tatransmissionSunYat-SenUniversityIntroduction3NetworksunderattackWhhatcanbbewrong?Howarecomputernetworksvulnerable?Whataresomeofthemoreprevalentattackstoday?Acknowledgement:PartoftheslidesareadoptedfromProf.KeithRoss’lecturenotes.SunYat-SenUniversityIntroduc

3、tion4ThebadguyscanputmalwareintoyourhostviatheInternetWeconnectourhhoststothheInternettogetgoodstuff:E-mail,webpages,mp3s,videoclips,searchresults,etc.Butalonggg,withthegoodstuff,comesthemalware:DeletefilesInstallspywarethatcollectsprivateinfoEnrollourcomprom

4、EnrollourcompromsedhostnabotnetisedhostinabotnetSunYat-SenUniversityIntroduction5Malware:self-reppglicatingOnceitinfectsonehost:seektksentryiitthntootherhhtostsandthenintoyetmorehostsVirus（病毒）Worms（蠕虫）Difference?Trojanhorse（木马）SunYat-SenUniversityIntroduction

5、6DifferenceVirusRequiressomeformofhumaninteractiontospreadClassicexample:E-mailvirusesWormsNouserreplicationneededWormininfectedhostscansIPaddressesandportnumbers,lookingforvulnerableprocessestoinfectTrojanhorseHidden,deviouspartofsomeotherwiseusefulsoftwareS

6、unYat-SenUniversityIntroduction7CaseStudyVirus:ILOVEYOU以电子邮件消息的形式发来，主题是ILOVEYOU，附件名为LOVE-LEEETTER-FOR-YOU.TXT.vbs向被感染者Outlook通讯簿名单发出自动信件，藉以连锁性的大规模散播，造成企业mailserver瘫痪Worm：CdRdCodeRed"HackdbChkedbyChinese!“Trojanhorse(木马)：盗版软件可通过QQ/网游外挂传播SunYat-SenUniversityInt

7、roduction8Thebadguysattackservers&networkinfrastructure:DoSattacksDenialofService:Diminishesusabilityofnetworkhost,network,ornetworkinfrastructure.Vulnerabilityattack:Attackersendswell-craftedmessagestoavulnerableapporOScrashingmessagestoavulnerableapporOS,cr

8、ashingserviceorhost.Bandwidthflooding:AttackersendsadelugeofpackketstohthetargetedhdhTost.Target’’saccessliliknkbecomesclogged..Connectionflooding:Theattackerestablisheslargenumberofhalf-