Eicon Networks S92 Manual de usuario descargar pdf (Pagina 105)

YuChakTinMichael‘sGIACGCFWProjectAssignment

Page 105

ConfiguringtheProxyServer

Refertot he“ProductsPreparation”section forinformationonMicrosoftISAServer.

Refertot he“ProductsPreparation”section forinformationonWindows2000hardening.

ThissectionfocusesontheconfigurationofISAServer’sProxyfunctions.Infact,

ISAServer’sroleintermsoffirewallinginthisprojectissimpleandstraight

forward:DropALLincomingrequestsmadefromtheinternet!

TheinternalstaffsatGIACneedtoaccesstheinternetfrequently.Itisnoteconomical

norscalableiftrueIPisimplementedforeachclient.Ontheotherhand,simpleNAT

doesnotproduceanyperformancebenefit. Thus,aproxyserverthatcombinesNAT

andcachingshouldbeimplemented.

Aproxyserverisaserverthatsitsbetweenaclientapplicationandarealserverthat

interceptsallrequeststotherealservertoseeifitcanfulfilltherequestsitself.As

describedbyWebopedia.com,proxyservershavetwomainpurposes:

“ImprovePerformance:Proxyserverscandramaticallyimproveperformancefor

groupsofusers.Thisisbecauseitsavestheresultsofallrequestsforacertain

amountoftime.ConsiderthecasewherebothuserXanduserYaccesstheWorld

WideWebthroughaproxyserver.FirstuserXrequestsacertainWebpage,which

we'llcallPage1.Sometimelater,userYrequeststhesamepage.Insteadof

forwardingtherequesttotheWebserverwherePage1resides,whichcanbea

timeconsumingoperation,the proxyserversimplyreturnsthePage1thatitalready

fetchedforuserX.Sincetheproxyserverisoftenonthesamenetworkastheuser,this

isamuchfasteroperation.Realproxyserverssupporthundredsorthousandsofusers.

Themajoronline servicessuchasCompuserveandAmericaOnline,forexample,

employanarrayofproxyservers.

FilterRequests: Proxyserverscanal so beusedtofilterrequests.Forexample,a

companymightuseaproxyservertopreventitsemployeesfromaccessingaspecific

setof Websites.”

20

http://www.webopedia.com/TERM/P/proxy_server.html

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Eicon Networks S92 Manual de usuario Pagina 105