Module10.ppt

Module10 NetworkinginLinux LinuxEssentials NetworkinginLinux IntroductionAcomputernetworkisdefinedasanumberofsystemsthatareconnectedtoeachotherandexchangeinformationacrossthenetworkconnection ThesystemnetworkisconfiguredbysettingtheIPaddresswhichisassignedbythesystemadministrator TheIPaddressprovidesbaseservicesfortransmittingdatabetweennetworksinTCP IP Transmissioncontrolprotocol Internetprotocol TopicsNetworkConnectivityIPaddressAccessingRemotesystemTransferringfilesInternetconfiguration TheLinuxsystemcanbeconnectedtothenetworkwiththehelpofnetworkhardware NetworkhardwarecanbeLAN Localareanetwork card cables hub switchorrouter Toconfigurethenetworkforthesystem TCP IP TransmissionControlProtocol InternetProtocol addressisrequiredfromthesystemadministrator TheIPaddresscanalsobeobtainedfromtheDHCP Dynamichostconfigurationprotocol serverconfiguredbythesystemadministrator Whenthesystemisconnectedtothenetwork theresourcescanbesharedanddatacanbetransferredamongthesystems TheLANservices telnet SSH SecureShell FTP Filetransferprotocol enablesthefiletransferandremotelogintothesystem NetworkinginLinux IPAddress AnIPaddressisa32bitbinarynumberusuallyrepresentedas4decimalvalues eachrepresenting8bits intherange0to255 knownasoctets separatedbydecimalpoints EverysysteminnetworkisassignedauniqueidentifyingnumbercalledIPaddress Itisusedinordertoidentifyandcommunicatewithdifferentsystemspresentinthenetwork ThedataissentacrossthenetworkandcontainsasourceanddestinationIPaddress Example 10 10 1 240130 130 1 10192 168 1 200 ConfiguringIPaddressThesystemcanbeapartofnetworkbyconfiguringtheIPaddress TheIPaddresscanbesetbytwooptionsinCUImodeandGUImode StaticIPDynamicIP DHCP IPAddress IPAddress StaticIP AstaticIPaddressisconfiguredmanuallybyphysicallyenteringtheIPaddressinconfigurationdialogboxanditdoesnotchangeuntilalteredmanually ThestaticIPisassignedbythesystemadministrator DynamicIP Inalargecomputernetwork theprocessofassigningIPaddressissimplifiedusingaDHCPserver ADHCPserverisusedtoautomaticallyassigntheIPaddresstothecomputersthatareconfiguredasaDHCPclient ThefollowingcommandsareusedtoconfigureandverifytheIPconfigservicenetworkrestartifconfigping StaticIPaddressinCUImodeConfigurationofthestaticIPaddressSyntaxTypethecommand netconfig PressEnterkey atthecommandpromptintheterminalwindow IPAddress networkserviceSyntax servicenetworkrestart IPAddress IPAddress ifconfig IPAddress ping IPAddress DynamicIPaddressinCUImodeConfigurationofthedynamicIPaddressSyntax netconfig PressEnterkey StaticIPaddressinGUImodeNetworkconfigurationinstaticIP IPAddress DynamicIPaddressinGUImodeDHCPsettings IPAddress IPAddress HostNameAhostnameistheuniquenameassignedtoeachhostonthenetwork ThehostnameisusedtoidentifyaparticularIPaddress Hostnamesareusedbyvariousnamingsystemsliketelnet ssh FTP GFTP NISandDNS TherearethreewaystoresolvehostnamestoIPaddressesonaLinuxsystem etc hostsDNS Domainnameservice NIS Networkinformationservice Contd etc hostsisaconfigurationfilemaintainedlocallyoneachhosttoresolvehostnamestoIPaddresses Onasmallnetwork itiseasytomaintainthenameresolutionofhostnamestoaddresses Whenaddingorremovinghosts orreassigningIPaddresses theuserhavetoupdatethe etc hostsfile DNS Domainnameservice willresolvethehostnamesintoIPaddressesinalargenetwork NIS Networkinformationservice providesacentralpointofadministrationforcommonconfigurationfileslike etc passwd etc hosts Itpreservestheconsistencyoftheconfigurationfilesacrossallthesystemsonthenetwork Itsimplifiesconfigurationfileupdatesconsiderably IPAddress SystemsinthenetworkcanbeaccessedremotelywithhelpofnetworkconnectivityandusingIPaddressesintwoways TelnetSSHTelnetTelnetisaterminalprogramforTCP IPnetworkssuchastheInternet Thetelnetprogramrunsonyourcomputerandconnectsyoursystemtotheothersystempresentinthenetwork Tostartatelnetsession youmustlogintoothersystembyenteringavalidusernameandpasswordoftheothersystem Contd AccessingRemoteSystem Contd AccessingRemoteSystem telnetsessionSyntax telnet SSHSSHisaprogramforloggingintoaremotemachineandforexecutingcommandsonaremotemachineTherootusercanloginthroughSSHandexecutethesystemadministrativecommand sshcommandSyntaxssh AccessingRemoteSystem Transferringfiles FilescanbetransferredamongvarioussystemsinthenetworkbyusingFTP GFTPandSCP securecopy FTPFTP Filetransferprotocol isaprogramthatallowsyoutotransferthefilesbetweencomputerspresentinthenetwork Itcanalsotransferthefilesamongdifferentoperatingsystems Example LinuxtoLinux LinuxtoWindows WindowstoLinux Syntax lftp GFTPGFTP Graphicalfiletransferprotocol isthetoolusedforuploadinganddownloadingthefilesinagraphicalmode GFTP Graphicalfiletransferprotocol session Contd Transferringfiles Transferringfiles SCP securecopy Thescpcommandisusedtocopythefilesfromothersystempresentinnetwork Syntax scp Example scpfile1192 168 1 171 root Internetconfiguration InLinux internetcanbebrowsedbothinGUImodeaswellasCUImode Theinternetcanbeconfiguredafterthenetworkconnectivity ConfiguringinternetinGUImodeStep1 Webbrowser Mozilla Step2 Proxyconfiguration Internetconfiguration Contd Step3 SettingtheproxyIPandtheportnumber Contd Internetconfiguration Contd Step4 VerifyingtheInternetconnectivity Internetconfiguration ModemModem standsformodulator demodulator isadevicethatenablesasystemtotransmitdataovertelephonelinesforinternetconnectivity Itconvertsdigitalcomputersignalsintoanalogformatfortransmissionofdata Internetconfiguration Internetconfiguration Connectiontointernetthroughmodem LabExercise HowtoconfiguretheIPaddressinCUImode Assumethatyoursystemadministratororlabin chargehasgivenyout