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OperatingSystem

AdHocInternetSharingwithMicrosoftWindowsXP

MicrosoftCorporation

Published:October2003

Updated:August2004

Abstract

TheInternetConnectionSharing(ICS)featureofMicrosoft@Windows@XPallowsyoutoshareasingleInternet

connectionwithmultiplecomputers.Built-insupportforIEEE802.11wirelessLANs(WLANs)allowsyouto

createanadhocwirelessnetwork.ThesetwofeaturescanbeusedtogethertoshareawiredInternet

connectionwiththemembersofanadhocwirelessnetwork.Thisarticledescribeshowtoquicklyandeasilyuse

WindowsXPtoshareawiredInternetconnectionwithotherWLANcomputers.

Microsoft@Windows@XPTechnicalArticle

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Contents

Overview1

ConfiguringAdHocInternetSharing2

1.ConnectingtheICSHostComputertotheInternet2

2.EnablingInternetSharingontheInternetConnectionoftheICSHostComputer4

3.CreatinganAdHocWirelessNetworkontheICSHostComputer4

4.ConnectingtotheNewAdHocWirelessNetworkfromtheOtherLaptopComputers6

RestoringtheConfigurationoftheICSHostComputer9

Summary10

RelatedLinks11

Microsoft@Windows@XPTechnicalArticle

Overview

WiththeInternetConnectionSharing(ICS)featureofWindowsXP,youcanshareaccesstotheInternet

withothercomputersofasmallnetwork.Forexample,whenyouhaveonecomputerthatconnectstothe

InternetbyusinganEthernetcableandICSisenabledontheEthernetconnectionofthiscomputer,known

astheICShostcomputer,theothercomputersonthesmallnetworkcanconnecttotheInternetthroughthe

ICShostcomputer.

WithIEEE802.11supportforwirelessLANs(WLANs),youcancreateanadhocwirelessnetwork,also

knownasacomputer-to-computerwirelessnetwork.Anadhocwirelessnetworkdoesnotrequiretheuse

ofawirelessaccesspoint,whichisaseparatedevicethatistypicallyusedbyprivateorganizationsand

publiclocationstoprovidecentralizedwirelessaccesstoalargernetwork.Youcanuseadhocwireless

networkstoconnectmultipleWLANcomputerstogetherinhomes,smallbusinesses,orfortemporary

connectivitybetweentwoormorecomputerssothattheycaneithercommunicatewitheachotherorwitha

sharedresource,suchastheInternet.Itisthislastcasethatwewillexploreinthisarticle.Wewilldescribe

thestepsrequiredtoconfigureacomputerrunningWindowsXPtoconnecttotheInternetusingan

EthernetconnectionandthensharethatInternetconnectionwithotherWLAN-basedcomputersusingan

adhocwirelessnetwork.

AdHocInternetSharingwithMicrosoftWindowsXP1

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ConfiguringAdHocInternetSharing

Thisconfigurationassumesthefollowingconfiguration:

?AlaptopcomputerrunningWindowsXPthatisequippedwithbothEthernetand802.11WLANnetwork

adapters.ThiscomputerisreferredtoastheICShostcomputer.

?AnEthernet-basedconnectiontotheInternet.

?LaptopsorothercomputersrunningWindowsXPthatareequippedwith802.11WLANnetwork

adapters.

Thefollowingfigureshowstheresultingconfiguration.

comcM9

C3I

cornpulef

ThestepstoconfiguringadhocInternetsharingarethefollowing:

i.ConnecttheICShostcomputertotheInternet.

2.EnableInternetsharingontheInternetconnectionoftheICShostcomputer.

3.CreateanadhocwirelessnetworkontheICShostcomputer.

4.Connecttothenewadhocwirelessnetworkfromtheotherlaptopcomputers.

Thefollowingsectionsdescribethesestepsindetail.

NoteThefollowingstepsassumethatthewirelessnetworkadaptersinstalledinallofthewirelessclientcomputerscan

connectusingacommon802.11technology,suchas802.11b,802.11g,or802.11a.

1.ConnectingtheICSHostComputertotheInternet

ConnectanEthernetcablethatleadstotheInternettotheEthernetadapterontheICShostcomputer.In

manycases,theInternetconnectionwillprovideautomaticIPaddressing.Toutilizethisfacilityofthe

Internetconnection,theEthernetconnectionintheNetworkConnectionsfolderinWindowsXPmustbe

configuredforautomaticaddressing.ToconfigureacomputerrunningWindowsXPforautomatic

addressing,dothefollowing:

1.FromtheWindowsXPdesktop,clickStart,clickControlPanel,clickNetworkandInternet

Connections,andthenclickNetworkConnections.

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2.Right-clickthenetworkconnectionthatcorrespondstotheEthernetnetworkadapterattachedtothe

Internet,andthenclickProperties.

3.OntheGeneraltab,double-clickInternetProtocol(TCP/IP)intheThisconnectionusesthe

followingitemslist.

4.OntheGeneraltab,clickObtainanIPaddressautomaticallyandObtainDNSserveraddress

automatically.Anexampleisshowninthefollowingfigure.

5.ClickOKtosavethechangestoyourconnection'sconfiguration.

IftheInternetconnectiondoesnotprovideautomaticIPaddressing,youmustmanuallyconfigureanIP

addressconfiguration.ToobtainanIPaddressconfiguration,seethenetworkadministratorofthenetwork

towhichyouareconnecting.TomanuallyconfigureacomputerrunningWindowsXPforanIPaddress

configuration,dothefollowing:

1.FromtheWindowsXPdesktop,clickStart,clickControlPanel,clickNetworkandInternet

Connections,andthenclickNetworkConnections.

2.Right-clickthenetworkconnectionthatcorrespondstotheEthernetnetworkadapterattachedtothe

Internet,andthenclickProperties.

3.OntheGeneraltab,double-clickInternetProtocol(TCP/IP)intheThisconnectionusesthe

followingitemslist.

4.OntheGeneraltab,clickUsethefollowingIPaddressandtypetheIPaddress,subnetmask,and

defaultgatewayasinstructed.ClickUsethefollowingDNSserveraddressesandtypetheIP

addressofapreferredandalternateDomainNameSystem(DNS)serverasinstructed.

5.ClickOKtosavethechangestoyourconnection'sconfiguration.

Next,youmustenabletheWindowsFirewallfeatureofWindowsXPwithServicePack2(SP2),theInternet

ConnectionFirewall(ICF)featureofWindowsXPwithServicePack1(SP1)orWindowsXPwithnoservice

packsinstalled,orathird-partyfirewalltohelpprotecttheICShostcomputerfrommaliciousInternetusers.

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ToenableWindowsFirewallontheICShostcomputer,dothefollowing:

i.FromtheWindowsXPdesktop,clickStart,clickControlPanel,clickNetworkandInternet

Connections,andthenclickWindowsFirewall.

2.ClickOn,andthenclickOK.

ToenableICFontheInternetconnectionoftheICShostcomputer,dothefollowing:

1.FromtheWindowsXPdesktop,clickStart,clickControlPanel,clickNetworkandInternet

Connections,andthenclickNetworkConnections.

2.Right-clicktheEthernetnetworkconnectionthatcorrespondstotheEthernetnetworkadapter

attachedtotheInternet,andthenclickProperties.

3.OntheAdvancedtab,selecttheProtectmycomputerbylimitingorpreventingaccesstothis

computerfromtheInternetcheckbox.

4.ClickOKtosavechangestoyourconnection.

AftertheICShostcomputerisconnectedtotheInternet,verifythatyouhaveInternetconnectivitybyusing

aWebbrowsersuchasInternetExplorertoviewafewWebsites.Toensurethatyouarenotviewing

locallystoredcopiesofWebpagecontents,refresheachWebpagethatyouview.

WhenyouareconfidentthatyouareaccessingtheInternetfromtheICShostcomputer,proceedtothe

nextstep.

2.EnablingInternetSharingontheInternetConnectionoftheICSHostComputer

ToenableInternetsharingontheInternetconnectionoftheICShostcomputer,dothefollowing:

1.FromtheWindowsXPdesktop,clickStart,clickControlPanel,clickNetworkandInternet

Connections,andthenclickNetworkConnections.

2.Right-clicktheEthernetnetworkconnectionthatisusedtoaccesstheInternet,andthenclick

Properties.

3.OntheAdvancedtab,selecttheAllowothernetworkuserstoconnectthroughthiscomputer's

InternetconnectioncheckboxandcleartheAllowothernetworkuserstocontrolordisable

thissharedInternetconnectioncheckbox.

4.ClickOKtosavechangestoyourconnection.

5.YoumightbepromptedwithaLocalNetworkmessageboxthatexplainshowyourcomputer's

configurationisbeingchanged.ClickYestoenableInternetsharing.

3.CreatinganAdHocWirelessNetworkontheICSHostComputer

TocreateanadhocwirelessnetworktoshareInternetaccesswiththeotherWLANcomputersona

computerrunningWindowsXPwithSP2orWindowsXPwithSP1andtheWPAWirelessSecurityUpdate

inWindowsXP,dothefollowing:

1.FromtheWindowsXPdesktop,clickStart,clickControlPanel,clickNetworkandInternet

Connections,andthenclickNetworkConnections.

2.Right-clickthewirelessnetworkconnection,andthenclickProperties.

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3.ClicktheWirelessNetworkstab.

4.Inthewirelessnetworkadapterpropertiesdialogbox,clickAddunderPreferrednetworks.

5.OntheAssociationtab,typethenameofyouradhocwirelessnetworkinNetworkname(SSID).

Forexample,youcouldnameyourwirelessnetworkAdHocInternet.

6.SelecttheThisisacomputer-to-computer(adhoc)networkcheckboxandcleartheThekeyis

providedformeautomaticallycheckbox.

7.InNetworkAuthentication,selectOpen.

8.InDataencryption,selectWEP.

9.InNetworkkey,typetheWEPkey.TheWEPkeyshouldbearandomsequenceofhexadecimal

digitsornumbers,letters,andpunctuation.

w.lnConfirmnetworkkey,retypetheWEPkey.

11.ClickOKtosavechangestothewirelessnetwork.

i2.ClickOKtosavechangestothewirelessnetworkadapter.

TocreateanadhocwirelessnetworktoshareInternetaccesswiththeotherWLANcomputersona

computerrunningWindowsXPwithSP1,dothefollowing:

1.FromtheWindowsXPdesktop,clickStart,clickControlPanel,clickNetworkandInternet

Connections,andthenclickNetworkConnections.

2.Right-clickthewirelessnetworkconnection,andthenclickProperties.

3.ClicktheWirelessNetworkstab.

4.Inthewirelessnetworkadapterpropertiesdialogbox,clickAddunderPreferrednetworks.

5.OntheAssociationtaboftheWirelessNetworkPropertiesdialogbox,typethenameofyourad

hocwirelessnetworkinNetworkname(SSID).Forexample,youcouldnameyourwirelessnetwork

AdHocInternet.

6.SelecttheDataencryption(WEPenabled)andThisisacomputer-to-computer(adhoc)

networkcheckboxesandcleartheThekeyisprovidedformeautomaticallycheckbox.

7.InNetworkkey,typetheWEPkey.TheWEPkeyshouldbearandomsequenceofhexadecimal

digitsornumbers,letters,andpunctuation.

8.RetypetheWEPkeyinConfirmnetworkkey.

9.ClickOKtosavechangestothewirelessnetwork.

w.ClickOKtosavechangestothewirelessnetworkadapter.

TocreateanadhocwirelessnetworktoshareInternetaccesswiththeotherWLANcomputersona

computerrunningWindowsXPwithnoservicepacksinstalled,dothefollowing:

1.FromtheWindowsXPdesktop,clickStart,clickControlPanel,clickNetworkandInternet

Connections,andthenclickNetworkConnections.

2.Right-clickthewirelessnetworkconnection,andthenclickProperties.

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3.ClicktheWirelessNetworkstab.

4.Inthewirelessnetworkadapterpropertiesdialogbox,clickAddunderPreferrednetworks.

5.IntheWirelessNetworkPropertiesdialogbox,typethenameofyouradhocwirelessnetworkin

Networkname(SSID).Forexample,youcouldnameyourwirelessnetworkAdHocInternet.

6.SelecttheDataencryption(WEPenabled)andThisisacomputer-to-computer(adhoc)

networkcheckboxesandcleartheThekeyisprovidedformeautomaticallycheckbox.

7.InKeyformat,selectakeyformat.

8.InKeylength,selectakeysize.

9.InNetworkkey,typetheWEPkey.TheWEPkeyshouldbearandomsequenceofhexadecimal

digitsornumbers,letters,andpunctuation.

w.ClickOKtosavechangestothewirelessnetwork.

11.ClickOKtosavechangestothewirelessnetworkadapter.

Theseinstructionsconfigureanencryptionkeyforwirelesscommunicationsontheadhocwirelessnetwork.

YoumusttelltheotheruserswhowanttoaccesstheInternettheWEPkey.Youcancreateanadhoc

wirelessnetworkwithoutrequiringencryptionandanencryptionkey,butitisnotrecommended.

4.ConnectingtotheNewAdHocWirelessNetworkfromtheOtherLaptop

Computers

Toconnecteachotherlaptopcomputertothenewlycreatedadhocmodewirelessnetwork,dothe

following:

1.Oncethenewadhocwirelessnetworkiscreated,WindowsXPonotherlaptopcomputersshould

detectitandpromptyouwithaOneormorewirelessnetworksareavailableorWireless

networksdetectedmessageinthenotificationareaofyourtaskbar.

2.Clickthenotificationmessage.

Ifyouarenotnotified,right-clickthewirelessnetworkadapterinNetworkConnectionsandclickView

AvailableWirelessNetworks.

YoushouldseetheWirelessNetworkConnectiondialogbox(forWindowsXPwithSP2),adialogbox

withthenameofthewirelessconnection(forWindowsXPwithSP1),ortheConnecttoWireless

Networkdialogbox(forWindowsXPwithnoservicepacksinstalled).AnexampleoftheWireless

NetworkConnectiondialogboxforWindowsXPwithSP2isshowninthefollowingfigure.

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3.ForWindowsXPwithSP2,clickthenameofthenewadhocwirelessnetworkinthelist,andthen

clickConnect.WhenpromptedbytheWirelessNetworkConnectiondialogbox,theWEPkeyin

NetworkkeyandConfirmnetworkkey,andthenclickConnect.

ForWindowsXPwithSP1,clickthenameofthenewadhocwirelessnetworkinAvailablenetworks,

typetheWEPkeyinNetworkkeyandConfirmnetworkkey,andthenclickConnect.

ForWindowsXPwithnoservicepacksinstalled,clickthenameofthenewadhocwirelessnetworkin

Availablenetworks,typetheWEPkeyinNetworkkey,andthenclickConnect.

Nowthatthelaptopcomputerisconnectedtotheadhocwirelessnetwork,youmustconfigureitforeither

WindowsFirewallorICFandautomaticaddressingbydoingthefollowing:

1.FromtheWindowsXPdesktop,clickStart,clickControlPanel,clickNetworkandInternet

Connections,andthenclickNetworkConnections.

2.Right-clickthenetworkconnectionthatcorrespondstothewirelessnetworkadapter,andthenclick

Properties.

3.ForcomputersrunningWindowsXPwithSP2,clicktheAdvancedtab,andthenclickSettings.

FromtheWindowsFirewalldialogbox,clickOn,andthenclickOK.

ForcomputersrunningWindowsXPwithSP1orWindowsXPwithnoservicepacksinstalled,clickthe

Advancedtab,andthenselecttheProtectmycomputerandnetworkbylimitingorpreventing

accesstothiscomputerfromtheInternetcheckbox.

4.ClicktheGeneraltab,double-clickInternetProtocol(TCP/IP)intheThisconnectionusesthe

followingitemslist.

5.OntheGeneraltab,clickObtainanIPaddressautomaticallyandObtainDNSserveraddress

automatically.

6.ClickOKtosavethechangestotheconfigurationofInternetProtocol(TCP/IP).

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7.ClickOKtosavethechangestoyourconnection'sconfiguration.

ThelaptopcomputershouldreceiveanIPaddressconfigurationfromtheICShostcomputerandhave

Internetconnectivity.TestInternetconnectivitybyusingaWebbrowsertoviewWebpages.

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RestoringtheConfigurationoftheICSHostComputer

AftertheadhocInternetsharingisnolongerneeded,youcanrestoretheconfigurationoftheICShost

computerrunningWindowsXPbydoingthefollowing:

1.FromtheWindowsXPdesktop,clickStart,clickControlPanel,clickNetworkandInternet

Connections,andthenclickNetworkConnections.

2.Right-clicktheEthernetnetworkconnectionthatisusedtoaccesstheInternet,andthenclick

Properties.

3.OntheAdvancedtab,cleartheAllowothernetworkuserstoconnectthroughthiscomputer's

Inte