Linux+ Guide to Linux Certification, Second Edition Chapter 14 Network Configuration.

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  • Linux+ Guide to Linux Certification, Second EditionChapter 14Network Configuration

    Linux+ Guide to Linux Certification, 2e

  • ObjectivesDescribe the purpose and types of networks, protocols, and media access methodsUnderstand the basic configuration of TCP/IPConfigure a NIC interface to use TCP/IP

    Linux+ Guide to Linux Certification, 2e

  • Objectives (continued)Configure a modem, ISDN, and DSL interface to use PPP and TCP/IPUnderstand the purpose of host names and how they are resolved to IP addressesUse common network utilities to interact with network services

    Linux+ Guide to Linux Certification, 2e

  • Networks and TCP/IPNetwork: Two or more computers joined via network media and able to exchange informationLocal Area Networks (LANs): Computers within close proximityWide Area Networks (WANs): Computers separated by large distancesInternet service provider (ISP): Company providing internet access

    Linux+ Guide to Linux Certification, 2e

  • Networks and TCP/IP (continued)Routers: Devices capable of transferring packets between networksProtocols: Set of rules for communication between networked computersPackets: Packages of data formatted by a network protocolMedia access method: Defines how networked computers share access to the physical medium

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  • Networks and TCP/IP (continued)Linux network protocols:TCP/IP (Transfer Control Protocol/Internet Protocol)UDP/IP (User Datagram Protocol/Internet Protocol)IPX/SPX (Internetwork Packet Exchange/Sequence Packet Exchange)AppletalkDLC (Data Link Control)DECnet (Digital Equipment Corporation network)

    Linux+ Guide to Linux Certification, 2e

  • Networks and TCP/IP (continued)Ethernet: Most common network media access methodToken Ring: Popular media access methodMedia access method usually contained on NIC or modem hardware

    Linux+ Guide to Linux Certification, 2e

  • The TCP/IP Protocol:IP AddressesIP address: Unique number that identifies a networked computerOctets: Series of four 8-bit numbersUnicast: Directed TCP/IP communication between two computers

    Linux+ Guide to Linux Certification, 2e

  • The TCP/IP Protocol:IP Addresses (continued)IP addresses composed of two parts:Network ID: Network computer is located onHost ID: Single computer on that networkCannot have two computers with same host ID on a networkOnly computers with same network ID can communicate without a router

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  • Subnet MasksDefine which part of IP address is the network ID and which part is the host IDSeries of four 8-bit numbersANDing: Calculate network and host IDs from an IP address and subnet maskCompare binary bits

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  • Subnet Masks (continued)Figure 14-1: A sample IP address and subnet mask

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  • Subnet Masks (continued)0.0.0.0 = all networks255.255.255.255 = all computers255 in an IP address can specify many hostsBroadcast addresses

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  • Default GatewayIP address on router that sends packets to remote networksRouters can distinguish between different networks Move packets between themHave assigned IP addresses on each attached network

    Linux+ Guide to Linux Certification, 2e

  • TCP/IP Classes and SubnettingIP address class defines default subnet mask of associated deviceMulticast: TCP/IP communication destined for a certain group of computersClass D addressesSubnetting: Divide a large network into smaller networksControl traffic flowTake bits from host ID, give to network ID

    Linux+ Guide to Linux Certification, 2e

  • TCP/IP Classes and Subnetting (continued)Table 14-1: IP address classes

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  • Configuring a NIC Interfaceifconfig command: Assign TCP/IP configuration to a NICAlso used to view configuration of all network interfaces in computerdhclient command: Receive TCP/IP configuration from DHCP or Boot Protocol (BOOTP) server

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  • Configuring a NIC Interface (continued)/etc/sysconfig/network-scripts/ifcfg- file: Stores NIC configurationsPacket internet groper (ping) command: Check TCP/IP connectivity on a network

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  • Configuring a NIC Interface (continued)Figure 14-2: Configuring network interfaces

    Linux+ Guide to Linux Certification, 2e

  • Configuring a NIC Interface (continued)Figure 14-3: Configuring TCP/IP information for a network interface

    Linux+ Guide to Linux Certification, 2e

  • Configuring a PPP InterfaceRun TCP/IP over serial lines Use a WAN protocolThree common Point-to-Point Protocol (PPP) technologies:ModemsISDNDSL

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  • Configuring a PPP Interface (continued)Figure 14-4: Adding a network interface

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  • Configuring a PPP Interface (continued)Figure 14-5: Selecting modem hardware

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  • Configuring a PPP Interface (continued)Figure 14-6: Selecting ISDN hardware

    Linux+ Guide to Linux Certification, 2e

  • Configuring a PPP Interface (continued)Figure 14-7: Specifying ISP settings

    Linux+ Guide to Linux Certification, 2e

  • Configuring a PPP Interface (continued)Information about PPP devices stored in files named ifcfg- /etc/sysconfig/network-scripts directoryOther configurations used by PPP daemon stored in /etc/ppp and /etc/isdn

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  • Configuring a PPP Interface (continued)Figure 14-8: Specifying TCP/IP settings

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  • Configuring a PPP Interface (continued)Figure 14-9: Configuring an xDSL connection

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  • Configuring a PPP Interface (continued)Figure 14-10: Activating a PPP connection

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  • Name ResolutionHostnames: User-friendly computer nameFQDN: Hostname following DNS conventionDNS: Hierarchical namespace for host nameshostname command: View or set a computers host name

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  • Name Resolution (continued)Figure 14-11: The Domain Name Space

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  • Name Resolution (continued)TCP/IP cannot identify computers via hostnamesMust map hostnames to IP addressesEntries in /etc/hosts fileISPs list FQDNs in DNS servers on InternetApplications request IP addresses associated with FQDN

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  • Connecting to Network ResourcesNetwork resources:Shared printersApplicationsFilesTo use network resources, must have appropriate network utilities

    Linux+ Guide to Linux Certification, 2e

  • Downloading Files Using FTPMost web browsers have built-in FTP utilityFTP utility: Downloads files from FTP servers

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  • Downloading Files Using FTP (continued)Figure 14-12: Using a Web browser FTP client

    Linux+ Guide to Linux Certification, 2e

  • Downloading Files Using FTP (continued)Table 14-2: Common FTP commands

    Linux+ Guide to Linux Certification, 2e

  • Downloading Files Using FTP (continued)Table 14-2 (continued): Common FTP commands

    Linux+ Guide to Linux Certification, 2e

  • Accessing Files with NFSNFS: Common method for file transfer between UNIX and Linux computersNot as common as FTPMount directory from a remote computer

    Linux+ Guide to Linux Certification, 2e

  • Accessing Windows FilesMount shared Windows directory to local directoryFilesystem must be smbfssmbmount command: Mount directories from Windows computerssmbclient utility: Connect to shares on a Windows systemumount command: Unmount Windows directories

    Linux+ Guide to Linux Certification, 2e

  • Running Remote ApplicationsAccess to BASH shell may be obtained by connecting to a server across a networktelnet utility: Most common utility used to obtain BASH shell over a networkNo encryptionSecure Shell (ssh) utility: Uses encryption

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  • Running Remote Applications (continued)rlogin: Obtain a shell from remote computer on networkr utilities allow access to remote computers without a passwordTrusted access: Computers allowed to access a computer without providing a password

    Linux+ Guide to Linux Certification, 2e

  • Accessing E-mailPost Office Protocol (POP): Download e-mail messages from e-mail serverInternet Message Access Protocol (IMAP): View e-mail messages across networkSimple Mail Transfer Protocol (SMTP): Sending mail from MUA to e-mail serverMozilla Mail is most common MUA for Linux

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  • Accessing E-mail (continued)Figure 14-13: Configuring a mail account in Mozilla Mail

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  • Accessing E-mail (continued)Figure 14-14: Using Mozilla Mail

    Linux+ Guide to Linux Certification, 2e

  • Accessing E-mail (continued)Linux systems typically use an internal mail system designed for administrationDaemons e-mail root user when important events or problems occurmail utility: Basic e-mail reader available on most Linux distributionsmutt utility: Popular MUA Can run in a terminal

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  • Accessing E-mail (continued)Figure 14-15: The mutt mail user agent

    Linux+ Guide to Linux Certification, 2e

  • SummaryA network is a collection of computers that are connected together and share informationProtocols define the format of information that is transmitted across a networkThe protocol used by the Internet and most networks is TCP/IPEach computer on a TCP/IP network must have a valid IP address and subnet mask

    Linux+ Guide to Linux Certification, 2e

  • Summary (continued)The /etc/sysconfig/network-scripts directory contains the configuration for NIC and PPP interfacesThe TCP/IP configuration of a network interface can be specified manually or obtained automatically from a DHCP or BOOTP serverHost names are used to easily identify computers on a network; host names that follow the DNS are FQDNs

    Linux+ Guide to Linux Certification, 2e

  • Summary (continued)Host names must be resolved to an IP address before network communication can take placeFiles, applications, and e-mail can be accessed across the network with the appropriate network utility

    Linux+ Guide to Linux Certification, 2e

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