LanScaper
TM
AppendixB:InternetProtocolDefinitions
ARP=AddressResolutionProtocol-UsedtodetermineEthernet(MAC)addresswhenadevice
startstocommunicatewithanother.TheIPaddressisknownandabroadcastisusedtorequestthe
specificIPaddresseddevicetorespondwithitsMACaddress,sofurthercommunicationcanbe
specificallyaddressedbetweenthetwo.
DHCP
DNS
Gateway
IP
IPAddress
ISP
LAN
NetworkMask
=DynamicHostConfigurationProtocol-UsedwhenanewIPdeviceisaddedtoaLAN
anditneedstogetinformationabouttheIPaddressesusedonthatLAN.OneDHCPservermust
bepresentontheLANtoprovidearesponsetoaDHCPrequesttransmittedtoabroadcastaddress
andinformthenewdeviceofseveralconfigurationdetails.ADHCPserverisnotrequiredona
LAN,butifitdoesnotexist,allthedevicesontheLANmustbemanuallyconfigured.Much
informationcanbeprovidedbytheDHCPserver,theLanScaper™requestsanduses:
-anIPaddressforitself(MyIP)
-theIPaddressoftheDHCPserverontheLAN
-theNetmaskinuse
-theIPaddressoftheRouterontheLAN
-theIPaddressoftheDNSserveraccessiblefromtheLAN
=DomainNameServer-ProvidestranslationofURLaddresses(www.yahoo.com)toIP
addresses(66.218.71.89),sothataccesstotheinternetdevicescanberequestedusinghuman-
understandableidentifiers.DNSserversarefoundontheinternet,andthusareofinteresttothe
LanScaper™becauseaccessing(PINGing)theDNSserverprovesthattheLanScaper™canaccess
adeviceontheWAN.
=Router-seebelow
=InternetProtocol-ActuallyTCP/IP=TransmissionControlProtocol/InternetProtocol,but
commonlyabbreviatedtoIP.CommunicationsaddressingschemedefinedbyDARPA(Defense
AdvancedResearchProjectsAgency)tocontrolthepubliclyaccessedinternetnetwork.
-Specificnumberassignedtoasingledevicetoallowittobeuniquelyidentifiedonthe
networktowhichitisconnected.OnaLAN,theIPaddressmustbewithintherangeofaddresses
definedforthatLANbytheNetworkMaskinuse.Ontheinternet,allIPaddressesmustbe
universallyuniquetoallowaddressingthatspecificdevice.IPaddressesconsistof4hexadecimal
digitsthatarecommonlywrittenin"dotteddecimal"format.192.168.254.4isanexample.Note
thateachsetofdecimalnumbersdividedbytheperiodsmustbeintherangeof0-255asthey
representhexadecimalvaluesof00-FF.
=InternetServiceProvider-Commercialsupplierofaccessmechanismsforpublicaccessto
theinternet.
=LocalAreaNetwork-Connectionmechanismforabusiness,home,schooloranygroupof
devicestocommunicatewitheachother.IntheLanScaper™case,itisagroupofcomputers,
printers,routersandpossiblyotherdevicesconnectedbyEthernet.DistinctfromtheWANdueto
theIPaddressingina"Subnet".
=SubnetMask-IPaddressingschemethatdividestheentireIPaddressnetwork
intosmallersections(Subnets).InthecaseoftheLanScaper™,theNetworkmaskisusedto
identifyanIPaddressasbeinglocatedeitherontheLAN(localsubnet)orontheInternet,and
thereforeaccessedovertheWAN.