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Linux+ Guide to Linux Certification, Second Edition. Chapter 14 Network Configuration. Objectives. Describe the purpose and types of networks, protocols, and media access methods Understand the basic configuration of TCP/IP Configure a NIC interface to use TCP/IP. Objectives (continued).
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Linux+ Guide to Linux Certification, Second Edition Chapter 14 Network Configuration
Objectives • Describe the purpose and types of networks, protocols, and media access methods • Understand the basic configuration of TCP/IP • Configure 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/IP • Understand the purpose of host names and how they are resolved to IP addresses • Use common network utilities to interact with network services Linux+ Guide to Linux Certification, 2e
Networks and TCP/IP • Network: Two or more computers joined via network media and able to exchange information • Local Area Networks (LANs): Computers within close proximity • Wide Area Networks (WANs): Computers separated by large distances • Internet 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 networks • Protocols: Set of rules for communication between networked computers • Packets: Packages of data formatted by a network protocol • Media access method: Defines how networked computers share access to the physical medium Linux+ Guide to Linux Certification, 2e
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) • Appletalk • DLC (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 method • Token Ring: Popular media access method • Media access method usually contained on NIC or modem hardware Linux+ Guide to Linux Certification, 2e
The TCP/IP Protocol:IP Addresses • IP address: Unique number that identifies a networked computer • Octets: Series of four 8-bit numbers • Unicast: 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 on • Host ID: Single computer on that network • Cannot have two computers with same host ID on a network • Only computers with same network ID can communicate without a router Linux+ Guide to Linux Certification, 2e
Subnet Masks • Define which part of IP address is the network ID and which part is the host ID • Series of four 8-bit numbers • ANDing: Calculate network and host IDs from an IP address and subnet mask • Compare binary bits Linux+ Guide to Linux Certification, 2e
Subnet Masks (continued) Figure 14-1: A sample IP address and subnet mask Linux+ Guide to Linux Certification, 2e
Subnet Masks (continued) • 0.0.0.0 = all networks • 255.255.255.255 = all computers • 255 in an IP address can specify many hosts • Broadcast addresses Linux+ Guide to Linux Certification, 2e
Default Gateway • IP address on router that sends packets to remote networks • Routers can distinguish between different networks • Move packets between them • Have assigned IP addresses on each attached network Linux+ Guide to Linux Certification, 2e
TCP/IP Classes and Subnetting • IP address class defines default subnet mask of associated device • Multicast: TCP/IP communication destined for a certain group of computers • Class D addresses • Subnetting: Divide a large network into smaller networks • Control traffic flow • Take 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 Linux+ Guide to Linux Certification, 2e
Configuring a NIC Interface • ifconfig command: Assign TCP/IP configuration to a NIC • Also used to view configuration of all network interfaces in computer • dhclient command: Receive TCP/IP configuration from DHCP or Boot Protocol (BOOTP) server Linux+ Guide to Linux Certification, 2e
Configuring a NIC Interface (continued) • /etc/sysconfig/network-scripts/ifcfg-<interface> file: Stores NIC configurations • Packet internet groper (ping) command: Check TCP/IP connectivity on a network Linux+ Guide to Linux Certification, 2e
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 Interface • Run TCP/IP over serial lines • Use a WAN protocol • Three common Point-to-Point Protocol (PPP) technologies: • Modems • ISDN • DSL Linux+ Guide to Linux Certification, 2e
Configuring a PPP Interface (continued) Figure 14-4: Adding a network interface Linux+ Guide to Linux Certification, 2e
Configuring a PPP Interface (continued) Figure 14-5: Selecting modem hardware Linux+ Guide to Linux Certification, 2e
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-<InternetServiceProviderName> • /etc/sysconfig/network-scripts directory • Other configurations used by PPP daemon stored in /etc/ppp and /etc/isdn Linux+ Guide to Linux Certification, 2e
Configuring a PPP Interface (continued) Figure 14-8: Specifying TCP/IP settings Linux+ Guide to Linux Certification, 2e
Configuring a PPP Interface (continued) Figure 14-9: Configuring an xDSL connection Linux+ Guide to Linux Certification, 2e
Configuring a PPP Interface (continued) Figure 14-10: Activating a PPP connection Linux+ Guide to Linux Certification, 2e
Name Resolution • Hostnames: User-friendly computer name • FQDN: Hostname following DNS convention • DNS: Hierarchical namespace for host names • hostname command: View or set a computer’s host name Linux+ Guide to Linux Certification, 2e
Name Resolution (continued) Figure 14-11: The Domain Name Space Linux+ Guide to Linux Certification, 2e
Name Resolution (continued) • TCP/IP cannot identify computers via hostnames • Must map hostnames to IP addresses • Entries in /etc/hosts file • ISPs list FQDNs in DNS servers on Internet • Applications request IP addresses associated with FQDN Linux+ Guide to Linux Certification, 2e
Connecting to Network Resources • Network resources: • Shared printers • Applications • Files • To use network resources, must have appropriate network utilities Linux+ Guide to Linux Certification, 2e
Downloading Files Using FTP • Most web browsers have built-in FTP utility • FTP utility: Downloads files from FTP servers Linux+ Guide to Linux Certification, 2e
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 NFS • NFS: Common method for file transfer between UNIX and Linux computers • Not as common as FTP • Mount directory from a remote computer Linux+ Guide to Linux Certification, 2e
Accessing Windows Files • Mount shared Windows directory to local directory • Filesystem must be smbfs • smbmount command: Mount directories from Windows computers • smbclient utility: Connect to shares on a Windows system • umount command: Unmount Windows directories Linux+ Guide to Linux Certification, 2e
Running Remote Applications • Access to BASH shell may be obtained by connecting to a server across a network • telnet utility: Most common utility used to obtain BASH shell over a network • No encryption • Secure Shell (ssh) utility: Uses encryption Linux+ Guide to Linux Certification, 2e
Running Remote Applications (continued) • rlogin: Obtain a shell from remote computer on network • “r” utilities allow access to remote computers without a password • Trusted access: Computers allowed to access a computer without providing a password Linux+ Guide to Linux Certification, 2e
Accessing E-mail • Post Office Protocol (POP): Download e-mail messages from e-mail server • Internet Message Access Protocol (IMAP): View e-mail messages across network • Simple Mail Transfer Protocol (SMTP): Sending mail from MUA to e-mail server • Mozilla Mail is most common MUA for Linux Linux+ Guide to Linux Certification, 2e
Accessing E-mail (continued) Figure 14-13: Configuring a mail account in Mozilla Mail Linux+ Guide to Linux Certification, 2e
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 administration • Daemons e-mail root user when important events or problems occur • mail utility: Basic e-mail reader available on most Linux distributions • mutt utility: Popular MUA • Can run in a terminal Linux+ Guide to Linux Certification, 2e
Accessing E-mail (continued) Figure 14-15: The mutt mail user agent Linux+ Guide to Linux Certification, 2e
Summary • A network is a collection of computers that are connected together and share information • Protocols define the format of information that is transmitted across a network • The protocol used by the Internet and most networks is TCP/IP • Each 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 interfaces • The TCP/IP configuration of a network interface can be specified manually or obtained automatically from a DHCP or BOOTP server • Host 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 place • Files, applications, and e-mail can be accessed across the network with the appropriate network utility Linux+ Guide to Linux Certification, 2e