Inthefieldsofphysicalsecurityandinformationsecurity,accesscontrolistheselectiverestrictionofaccesstoaplaceorotherresource.Theactofaccessingmaymeanconsuming,entering,orusing.Permissiontoaccessaresourceiscalledauthorization(授权)． Anaccesscontrolmechanism(71)betweenauser(oraprocessexecutingonbehalfofauser)andsystemresources,suchasapplications,operatingsystems,firewalls,routers,files,anddatabases.Thesystemmustfirstauthenticate(验证)auserseekingaccess.Typicallytheauthenticationfunctiondetermineswhethertheuseris(72)toaccessthesystematall.Thentheaccesscontrolfunctiondeterminesifthespecificrequestedaccessbythisuserispermitted.Asecurityadministratormaintainsanauthorizationdatabasethatspecifieswhattypeofaccesstowhichresourcesisallowedforthisuser.Theaccesscontrolfunctionconsultsthisdatabasetodeterminewhetherto(73)access.Anauditingfunctionmonitorsandkeepsarecordofuseraccessestosystemresources. Inpractice,anumberof(74)maycooperativelysharetheaccesscontrolfunction.Alloperatingsystemshaveatleastarudimentary(基本的),andinmanycasesaquiterobust,accesscontrolcomponent.Add-onsecuritypackagescanaddtothe(75)accesscontrolcapabilitiesoftheOS.Particularapplicationsorutilities,suchasadatabasemanagementsystem,alsoincorporateaccesscontrolfunctions.Externaldevices,suchasfirewalls,canalsoprovideaccesscontrolservices.
A.components B.users C.mechanisms D.algorithms正确答案B
