serieshttp

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Shietal.
(Eds.
):ICCS2007,PartIII,LNCS4489,pp.
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Springer-VerlagBerlinHeidelberg2007ExperimentofEventInjectionTechnologyforNetworkDependabilityEvaluationYonggangPang1,HuiqiangWang1,andYeDu21CollegeofComputerScienceandTechnology,HarbinEngeeringUniversity150001Harbin,Chinapangyonggang@hrbeu.
edu.
cn,wanghuiqiang@hrbeu.
edu.
cn2CollegeofComputer,BeijingJiaotongUniversity,100044Beijing,Chinamail_dy@163.
comAbstract.
Dependabilityevaluationofcomputernetworkisanintegratedandcomplexresearchproblem.
Evolvingfromfaultinjection,eventinjectioncanbebetterusedtoevaluatedependabilityofcomputernetworksystem.
Accordingtotheprincipleofeventinjection,anexperimentmodelfornetworkdependabilityevaluationwasdesignedandcorrelativeexperimentswerecarriedout.
Atlast,applicationofeventinjectionfordependabilityevaluationoncomputernetworkwasdiscussed.
Keywords:dependabilityevaluation;eventinjection;DDoS;Loadrunner.
1IntroductionInsomeimportantdomains,suchasnationaldefense,avigation,financeandtranspor-tation,dependabilityofitscomputernetworksystemisanimportantproblem.
De-pendabilityofasystemisrelatedtonetworkreliability,availability,securityandsafety,sohowtoevaluatetheintegrateddependabilityisaproblemtobesolvedur-gently[1].
Nowadays,theresearchondependabilityofcomputernetworksystemconcludesimportantserversystem,small-sizenetworkandwebapplicationnetwork,andtheconceptionofdependabilityisstilldeveloping.
However,method,modelandrelativeindexsystemofdependabilityevaluationarelacking,researchonthesedo-mainssillneedtobefurthercarriedon.
Eventinjectiontechnologyisintroducedtotheresearchondependabilityevalua-tionofnetworksystem,bywhichtheintegrateddependabilityofatargetsystemcanbetested[2].
Eventinjectiontechnologyadaptsbettertotheexperimentinthecom-puternetworkenvironmentthanfaultinjection.
Intheeventinjectionexperiment,relativecharacteristiceventscanbeinjectedintothesystemtocheckitsreactionac-cordingtotherelativeattributesandcharactersofdependabilityevaluation.
Thispapersequentiallydissertatestheconceptionofeventinjectiontechnology,someeventinjectionexperimentsandintegratedjudgmenttotheexperiments.
Atlast,someproblemsofeventinjectiontechnologyinnetworkexperimentarediscussed.
142Y.
Pang,H.
Wang,andY.
Du2DependabilityofComputerNetworkThenewconceptionofdependability[3]wasformallyadvancedbyJ.
C.
Lapriein1985,whichincludedconceptionsofreliability,availability,maintainabilityandsafetyatthattime,thatistosay,thereliablecomputingandfault-tolerancewerejoinedintothecon-ceptionofdependability.
Fromthemediumtermof1980s',fault-tolerancetechnologywasappliedtodealwiththesecuritythreatandaseriesofexploringresearchesonhos-tilefailureproblemsledtoafusionofthetwoconceptionsofsecurityanddependablecomputing.
Afterthat,deepandclosediscussionofsomeexpertscausedtheappearanceofanacademicpatentwhichhasfurthereffect[4].
Afterthat,J.
C.
Lapriedeeperillus-tratedhisviewpointmanytimesatdifferentoccasions.
After1995,withtheworseningofInternetsecurity,togetherwiththedevelopingofsecuritytechnologiesandchangingofattackmeans,peoplehadtoafreshscantheessenceofdependablecomputingandsecuritycomputing.
AndthenewconsiderationofdependablecomputingandsecuritycomputingbyA.
Avizienis,,J.
C.
LaprieBrianRandell,andCarlLandwehrreflectedthenewestchanges.
CorrelativeconceptionsincludingtrustedcomputingfromU.
S.
military[5]andtrustworthycomputingadvancedbyBillGatesofMicrosoftdeveloped.
Duringre-searchondependability[6],correlativeconceptionsaredevelopingcontinuously,butthereisn'tuniformstandard.
3EventInjectionModelDuringthedependabilityevaluationonsystem,therewerenotonlytraditionalexactmodelssuchasthenetworkhardwarereliabilityproblems,butalsothenon-accuratemodels,suchasthesecurityproblem,soeventinjectionevolvingfromfaultinjectioncansolvetheseproblemsbetter.
Eventinjectiontechnologyisanexperimentalprocess,inwhichdifferentkindsofsystemeventsincludingreliabilityevents,availabilityevents,securityeventsofnet-worksystemareinjectedintothetargetsystem,atthesametime,responseinforma-tionofinjectedeventsisanalyzedorcalledbackbycorrespondingsystem,andatlastrelativeresultsareprovidedtoexperimenters.
Keytechnologiesaffectingthedepend-abilityevaluationresultbyeventinjectiontechnologymainlyare:selectionofeventmodellibrary,statisticaleventcoverage,andexperimentcomprehensiveevaluation.
3.
1SelectionofEventModelLibraryEventmodellibraryshouldincludetheeventsthatcaninfluencetheserviceabilityofthetargetsystem.
Theinjectedeventmodelselectedismoresimilartotheeventsoccurredduringtheactualrunningofthesystemorcoversthemtothegreatestextent,theresultsoftheexperimentwillbemoreaccurate.
Asuitableeventmodellibraryshouldfollowtwoprinciples:Firstly,itshouldincludeamajorityofeventmodelsthatcaninfluencetheactualrunningofthesystemandcauseperformancedeclineofthetargetcomputersystems;Secondly,eventmodelsinitcandetectthevulnerabilityofthetargetsystem.
ExperimentofEventInjectionTechnologyforNetworkDependabilityEvaluation1433.
2StatisticalEventCoverageTheeventsinjectedintoanrunningsystemcan'tincludealloftheeventsfacedbysystemapplicationsandinjectionstrategyofoneeventcan'trepresententirein-stances,atthesametime,harmextentsofdifferenteventsfacedbysystemarediffer-entfromeachother,soduringthedependabilityevaluationonthetargetsystem,thesatisfactorydegreewhichisnamedasstatisticaleventcoverageshouldhaveacredi-bilityinterval.
3.
3ExperimentComprehensiveEvaluationComputernetworkdependabilityevaluationincludesreliability,availability,safetyandsecurity,andsoon,moreoverthenetworksystemcanbedividedintolocalareanetwork,distributednetworkandinternet,thereforethenetworksystemdependabilityresearchisverybroad,thecorrespondingtestdatawillbemassive,howtoobtainasystem'dependabilitydegreeisacomplexquestion.
4EventInjectionExperimentInthenetworkdependabilityevaluation,thenetworkserviceperformanceandsecu-rityareveryimportant.
Thisarticlesimulatesandevaluatesthewebserverinnetworkusingeventinjectiontechnology,useLoadrunnertotestthebasicperformanceofthenetworkandusetheDDoSattacktesttoinfluencethesystem.
Thisexperimentistotesttheoperatingperformanceofthetargetsystem,Load-Runner8.
0testsoftwareisused.
Theresultscanthenbeanalyzedindetails,toexplorethereasonsforparticularbehaviour.
thedatainTable1willbeusedastheindexdatainthedependabilityevaluationtothetargetserversystem.
Table1.
MaintesingdataofwebseverMeasureeventsindexminmaxaverageConnectionshutdowns0.
12583.
06342.
497connectionrateNewconnections0.
10783.
12542.
563errorrateError-2662805.
4382.
745HitsperSecHits/s0.
286153.
06375.
377HTTP_2000.
14391.
84441.
775HTTP_403075.
7533.
291HTTPRe-sponsesperSec_HTTP_40400.
6250.
311flowspeedB/s2313591651340855DDoSmakesthefailureofattackednetworkserver.
InFigure1andFigure2,theserveraverageresponsetimeincreasesalongwiththeattackflowincrease,themeanflowspeedreducesalongwiththeattackflowincrease.
Atthesametime,alongwiththeattackdurationextension,theserveraverageresponsetimeincreases,meanflowspeedreduces.
Whentheattackcomputerincreases,theserverresponse144Y.
Pang,H.
Wang,andY.
DuFig.
1.
AverageresponsetimecurvesofserverFig.
2.
Averageflowspeedcurvesofservertimeobviouslyincreases,withtheserverprocessingattackrequesteventincreases,theserverresponseslowsdowneveninthesameflowsituation.
5ConclusionsIntheexperimentmethod,eventinjectiontechnologycanpreferablysolvetheprob-lemsofnetworkdependabilityevaluation.
Eventinjectiontechnologycannotonlyanalyzethecaseswhenthetargetsystemfailbutalsoanalyzethecaseswhenthecapabilityoftargetsystemperformancedeclinesorthesystemnotbeingabletooffersatisfiedservicestousers.
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