网络安全与防火墙 英文文献翻译文档格式.docx

网络安全与防火墙 英文文献翻译文档格式.docx

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Asthekeyfacilitythatmaintainsthenetworksecurity,firewallstakethepurposeofestablishinganobstaclebetweentrustandtrustlessnetwork,andputcorrespondingsafetystrategyintopractice.Inthispaper,thecomputernetworksecurityandthetechniquesoffirewallsweremainlydiscussed,theconceptandclassificationofthefirewallswereintroduced.Italsointroducedthreekind'

sofbasicimplementtechniquesofthefirewalls:

Packetfiltering,ApplicationProxyandMonitormodelindetail.FinallydescribedthetrendofdevelopmentofthefirewallstechniquesinInternetbriefly.

Keywords:

networksecurity,firewalls,Packetfiltering,monitor

1.Introduction

Nowwiththecomputernetworkande-commerceusedwidely,networksecurityhasbecomeanimportantproblemthatwemustconsiderandresolve.Moreandmoreprofessions.enterprisesandindividualssurferfromthesecurityproblemindifferentdegree.theyarelookingforthemorereliablesafetysolution.Inthedefensesystemadoptedbynetworksecurityatpresent,thefirewallsstandtheveryimportantposition.

Asthekeyfacilitythatmaintainsthenetworksecurity.firewallstakethepurposeofestablishinganobstaclebetweentrustandtrustlessnetwork,andputcorrespondingsafetystrategyintopractice.

AllthefirewallshavethefunctiontofiltertheIPaddress.ThistaskcheckstheIPpacket,makesthedecisionwhethertoreleaseortoabandonitaccordingtothesourceaddressanddestinationaddressoftheIP.ShowninFig.I,thereisafirewallbetweentwonetworksections,anUNIXcomputerisononesideofthefirewall,andtheothersideisaPCclient.WhilethePCclientasksatelnetrequestfortheUNIXcomputer,theclientprocedureoftelnetinthePCproducesaTCPpacketandpassesthepackettothelocalprotocolstacktopreparetosend.TheprotocolstackfillsitinoneIPpacket.then,sendsittoUNIXcomputerthroughthepathdefinedbytheTCP/IPstackofPC.TheIPpacketcan'

treachtheUNIXcomputeruntilitpassesthefirewallbetweenthePCandtheUNIXcomputer.

Fig.IIpAddressFiltering

TheapplicationfirewallisaveryefficientmeansofnetworksecurityonInternet,itisinstalledbetweenthetrustandtrustlessnetwork,canisolatetheconnectionbetweenthetrustandtrustlessnetwork,anddoesn'

thamperpeople'

saccesstothetrustlessnetworkatthesametime.ItcanisolatetheconnectionbetweentheriskareanamelytheremaybeacertainriskonInternetandthesafeareaLAN,anddoesn'

saccesstotheriskareaatthesametime.Firewallcanmonitorthetrafficflowinginandoutfromthenetworktofinishthetaskseeminglyimpossible;

itonlyallowsthesafeandcheckedinformationtoenterinto,andmeanwhileresistsonthedatathatmaybringaboutthethreattoenterprise.Asthefaultanddefectofthesecurityproblembecomemoreandmoregeneral,theinvasiontothenetworknotonlycomesfromthesuperattackmeans,butalsomaybefromthelower-levelmistakesorimproperpasswordselectionsontheconfiguration.So,thefunctionofthefirewallsispreventingthecommunicationthatnothopedandauthorizedpassesinandoutofthenetworkprotected.forcingthecompaniestostrengthentheirownnetworksecuritypolicy.Thegeneralfirewallscanachievethefollowingpurposes:

First,restrainingothersfromenteringtheinsidenetwork,filteringtheunsafeserviceandillegaluser;

Second,preventingtheinvadersfromclosingtoyourdefenseinstallation;

Third,limitingtheusertoaccessthespecialsite;

Fourth,providingconvenienceformonitoringtheInternetsecurity.

2.Theclassificationandimplementtechnologyoffirewalls

Anintegratedfirewallssystemusuallyconsistsofscreeningrouterandproxyserver.Thescreeningrouterisamulti-portIProuter.itchecktheeachcomingIPpacketaccordingtothegroupregulartojudgewhethertotransmitit.Thescreeningroutergetsinformationfromthepacket.fotexampletheprotocolnumber.theIPaddressandportnumberthatreceivingandsendingmassages.theflagoflinkevensomeotherIPselections.filteringIPpacket.Theproxyserverareserverprocessinthefirewall.itcanreplacethenetworkusertofinishthespecificTCP/IPfunction.Aproxyserverisnaturallyagatewayofapplicationlayer.agatewayoftwonetworksjoinedspecificnetworkapplication.UserscontactwithproxyserverbyoneoftheTCP/IPapplicationsuchasTelnetorFTP.theproxyserverasktheusersforthenameoftheremotehost.whichuserswanttoaccess.Aftertheusershaveansweredandofferedthecorrectusers'

identitiesandauthenticationinformation,theproxyservercommunicatestheremotehost,actastherelaybetweentwocommunicationsites.Thewholecoursecanbetotallytransparenttousers.

Therearemainlythreetypesinthefirewalls:

packetfiltering.applicationgatewaysandstatedetection.

Packetfilteringfirewallworksonthenetworklayer.itcanfilterthesourceaddress.destinationaddress.sourceportanddestinationportofTCP/IPdatapacket.Ithasadvantagessuchasthehigherefficiency.

transparenttouser.andusersmightnotfeeltheexistenceofthepackerfilteringfirewall,unlessheistheillegaluserandhasbeenrefused.Theshortcomingsarethatitcan'

tensurethesecuritytomostservicesandprotocols,unabletodistinguishthedifferentusersofthesameIPaddresseffectively,anditisdifficulttobeconfigured,monitoredandmanaged.can'

tofferenoughdailyrecordsandwarning.

Theapplicationgatewaysfirewallperformsitsfunctionontheapplicationlayer,itconnectswithspecificmiddle-jointfirewallbyaclientprocedure,andthenthemiddle-jointconnectswiththeserveractually.Unlikethepacketfilteringfirewall.whenusingthefirewallofthiskind.thereisnodirectconnectionbetweentheoutsidenetworks.soevenifthematterhashappenedinthefirewall.theoutsidenetworkscan'

tconnectwithnetworksprotected.Theapplicationgatewayfirewalloffersthedetaileddailyrecordsandauditingfunction,itimprovedthesecurityofthenetworkgreatly.andprovidesthepossibilitytoimprovethesecurityperformanceoftheexistingsoftwaretoo.Theapplicationgatewaysfirewallsolvesthesafetyproblembasedonthespecificapplicationprogram.theproductsbasedonProxywillbeimprovedtoconfiguretheserviceincommonuseandnon-standardport.However.solongastheapplicationprogramneedsupgrading.theusersbasedonProxywillfindthattheymustbuynewProxyserver.Asatechniqueofnetworksafety.Firewallcombinedwithproxyserverhassimpleandpracticalcharacteristics,canreachacertainsecurityrequestincaseofnotrevisingtheoriginalnetworkapplicationsystem.However.ifthefirewallsystemisbrokenthrough.thenetworkprotectedisinhavingnostateofprotecting.AndifanenterprisehopestolaunchthebusinessactivityonInternetandcarryoncommunicationwithnumerouscustomers.itcan'

tmeetthedemands.Inaddition,thefirewallbasedonProxyServicewilloftenmakestheperformanceofthenetworkobviouslydrop.

Thethirdgenerationoffirewalltakesthedetectiontechniqueofstateasthecore,combinesthepacketfilteringfirewallandapplicationgatewaysfirewall.Thestatedetectionfirewallaccessesandanalyzesthedataachievedfromthecommunicationlayerthroughthemoduleofstatedetectiontoperformitsfunction.Thestatemonitoractasfirewalltechnique.itisbestinsecurityperfonnance,itadoptsasoftwareengine.

whichexecutesthetacticsofnetworksecurityonthegateways,calledthedetectionmodule.Onthepremiseofnotinfluencingthenetworktoworknormally,detectionmodulecollectstherelevantdatatomonitoreachofthenetworkcommunicationlayers,collectsapartofdata,namelystatusinformation,andstoresthedataupdynamicallyforthereferenceinmakingsecuritydecisionafterward.Detectionmodule

supportsmanykindsofprotocolsandapplicationprogram,andcanimplementtheexpansionofapplicationandserviceveryeasily.Differentfromothersafetyschemes,beforetheuser'

saccessreachestheoperatingsystemofnetworkgateways,thestatemonitorshouldcollecttherelevantdatatoanalyze,combinenetworkconfigurationandsafetyregulationtomakethedecisionsofacceptance,refutation,appraisalorencryptingtothecommunicationetcOnceacertainaccessviolatesthesecurityregulation,thesafetyalarmwillrefuseitandwritedowntoreportthestateofthenetworktothesystemmanagementdevice.Thistechnologyhasdefectstoo,namelytheconfigurationofthestatemonitorisverycomplicated,andwilldeceleratethenetwork.

3.Newgenerationtechniqueoffirewalls

Accordingtothepresentfirewallsmarket,thedomesticandinternationalmanufacturersoffirewallcanallsupportthebasicfunctionofthefirewallwell,includingaccesscontrol,thenetworkaddresstransform,proxy,authentication,dailyrecordsauditetc.However,asstatedbefore,withtheattacktothenetworkincreasing,anduser'

srequisitionfornetworksecurityimprovingdaybyday,thefirewallmustgetfurtherdevelopment.Combinethepresentexperienceofresearchanddevelopmentandtheachievement,somerelevantstudiespointout,accordingtothedevelopmenttrendofapplicationandtechnology,howtostrengthenthesecurityoffirewall,improvetheperformanceoffirewall,enrichthefunctionoffirewall,willbecometheproblemthatthemanufactureroffirewallsmustfaceandsolvenext.

Thepurposeofthenewgenerationfirewallismainlycombiningthepacketfilteringandproxytechnology,overcomingthedefectsinthesafetyresp