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Network Guide to Networks, Fourth Edition


Title: Linux+ Guide to Linux Certification Subject: Chapter One Created Date: 9/27/2002 11:29:22 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Network Guide to Networks, Fourth Edition

Network Guide to Networks, Fourth Edition
  • Chapter 9
  • Networking with UNIX-Type of Operating Systems

A Brief History of UNIX
  • UNIX led to development of TCP/IP
  • Numerous vendors sell different UNIX varieties
  • Ken Thompson and Dennis Ritchie developed UNIX at
    Bell Labs (part of ATT)
  • System V
  • UNIX source code was cheaply available from ATT
  • Quickly distributed to many organizations

A Brief History of UNIX (continued)
  • Berkeley Software Distribution (BSD) Berkeley
    versions of UNIX
  • Added TCP/IP network subsystem to UNIX
  • ATT sold rights to UNIX
  • Now owned by two groups
  • The SCO Group owns rights to UNIX source code
  • The Open Group owns UNIX trademark

Varieties of UNIX
  • All flavors of UNIX share the following features
  • Support multiple, simultaneously logged-on users
  • Coordinate multiple, simultaneously running tasks
  • Mount disk partitions on demand
  • Apply permissions for file and directory access
    and modification
  • Uniform method of issuing data to or receiving
    data from hardware devices, files, and running
  • Start programs without interfering running

Varieties of UNIX (continued)
  • All flavors of UNIX share the following features
  • Hundreds of subsystems, including dozens of
    programming languages
  • Source code portability
  • Window interfaces (e.g., X Windows)
  • Two main categories
  • Proprietary
  • Open source

Proprietary UNIX
  • Source code either unavailable or available only
    by purchasing licensed copy from the SCO Group
  • Mac OS X Server Apple
  • Runs on PowerPC-based computers
  • Solaris Sun
  • Runs on SPARC-based workstations and servers,
    Intel-based Pentium-class workstations and
  • Runs on PowerPC-based computers
  • Does not run on Macs

Proprietary UNIX (continued)
  • Advantages
  • Accountability and support
  • Optimization of hardware and software
  • Predictability and compatibility
  • Customer has no access to systems source code
  • Cannot customize

Open Source UNIX
  • Open source software available to anyone, without
    licensing fees
  • Open source UNIX flavors
  • GNU
  • BSD
  • Linux
  • Users can modify code
  • Add functionality
  • Can be installed on wide range of systems

Three Flavors of UNIX
  • Solaris used by Sun Microsystems on its
    SPARC-based servers
  • Linux follows standard UNIX conventions, highly
    stable, and free
  • Developed by Linus Torvalds in 1991
  • Widely supported and used
  • Mac OS X Server Runs on Apples Xserve line of
    computers as well as Power Mac computers
  • All support TCP/IP and other protocols
  • Support many network topologies and physical media

UNIX Server Hardware Requirements
  • Any UNIX-type OS can act as a workstation or
    server OS
  • Use of GUI optional
  • Command line interface
  • To estimate additional hardware required
  • Server usage?
  • Applications and services to be run on server?
  • Number of users?
  • Peak usage time periods?
  • Maximum tolerable downtime?

A Closer Look at UNIX UNIX Multiprocessing
  • Allocate separate resources (e.g., memory space)
    to each process as it is created
  • Enables partitioning of processes in memory
  • Prevent programs from disrupting operation of
    entire system
  • Support symmetric multiprocessing (SMP)
  • Solaris up to 128 processors
  • Linux up to 32 processors
  • Mac OS X Server up to 2 processors

The UNIX Memory Model
  • Use both physical and virtual memory efficiently
  • Allocate memory area for each application
  • Sharing memory between programs wherever possible
  • Increases efficiency
  • Most use 32-bit addressing scheme
  • Enables programs to access 4 GB of memory
  • Most can run on CPUs employing 64-bit addresses
  • Virtual memory disk partition or a file

The UNIX Kernel
  • Core of all UNIX-type of systems
  • Loaded into memory and runs computer turned on
  • Coordinates access to computers hardware
  • Can add or remove functionality by loading and
    unloading kernel modules
  • Files containing instructions for performing
    specific tasks
  • Kernel origins
  • Solaris original ATT UNIX software
  • Linux Linus Torvalds
  • Mac OS X Server (XNU) Mach

UNIX System File Services
  • Disk File Systems
  • OSs facility for organizing, managing, and
    accessing files through logical structures and
    software routines
  • Native file system type on Linux is ext3
  • Solaris employs UFS
  • Mac OS X Server employs HFS file system
  • Can access FAT and NTFS partitions

UNIX System File Services (continued)
  • Network File Systems (NFSs) analogous to Windows
    shares or NetWare network volumes
  • Attach shared file systems (or drives) from
    Windows, NetWare, or other UNIX servers and share
    files with users on other computers
  • Sun Microsystems NFS
  • Samba open source application that implements
    Windows SMB and CIFS file system protocols
  • Included with Solaris, most Linux distributions,
    and Mac OS X Server systems by default
  • Mac OS X Server uses AFP

A UNIX Command Sampler (continued)
Table 9-4 Commonly used UNIX commands
A UNIX Command Sampler (continued)
Table 9-4 (continued) Commonly used UNIX commands
A UNIX Command Sampler (continued)
Table 9-4 (continued) Commonly used UNIX commands
A UNIX Command Sampler (continued)
  • Most frequently used UNIX command is ls
  • For each file, system stores all information
    (except filename) in a file information node
  • Beginning of disk partitions contain reserved
    space for all i-nodes on partition
  • Contain pointers to actual file contents
  • Pipe () combine commands
  • Output of one command is input to next
  • Pipeline two or more commands connected by a pipe

A UNIX Command Sampler (continued)
Figure 9-3 Anatomy of ls l output
Administering a UNIX-type of Server
  • User names and passwords used to connect clients
    to network
  • Access rights for groups
  • Users may be members of multiple groups
  • groupadd command enables addition of new group
  • useradd command enables addition of new users
  • Mac OS X Server uses GUI Workgroup Manager

Establishing Groups and Users on Linux and Solaris
  • groupadd command creates new group ID and makes
    group available for use
  • Assign unique ID number to each group
  • Does not automatically assign access rights
  • useradd command adds new user ID
  • Creates user ID and assigns it to one or more
  • -g option specifies initial group
  • -G option specifies additional groups

Establishing Groups and User on Mac OS X Server
  • Use Workgroup Manager application
  • Creating new group does not assign users
  • Assign unique name and numeric ID to groups

Establishing Groups and User on Mac OS X Server
Figure 9-4 User creation in Mac OS X Servers
Workgroup Manager
Changing File Access Permissions
  • Every file and directory is owned by exactly one
    user and is a member of exactly one group
  • By default, when a user creates a file or
    directory, that user is the file or directorys

Changing File Access Permissions on Linux and
  • Use chgrp command to assign a file or directory
    to a group
  • Use chmod command to change file and directory
  • Uses two sets of abbreviations to specify
    permission changes for files
  • First set identifies for whom change will occur
    files owner (u for user), files group (g),
    all others (o)
  • Second set identifies access rights read (r),
    write (w), and execute (x)
  • Separated by plus or minus sign

Changing File Access Permissions on Mac OS X
  • Accomplished through the GUI
  • Must be logged on as system administrator

  • UNIX is a stable, flexible, and efficient NOS
    that relies on TCP/IP and forms the basis of much
    of the Internet
  • Many varieties of UNIX-type of systems exist, and
    each of these belong to one of two categories
    proprietary and open source
  • Characteristics of UNIX-type of systems include
    the ability to support multiple, simultaneous
    users hierarchical files a uniform method for
    interacting with files, devices, and programs
    hundreds of subsystems and dozens of programming
    languages and source code portability

Summary (continued)
  • UNIX-type of systems use virtual memory and also
    allocate a memory area for each application
  • The UNIX kernel, the core of the OS, is loaded
    into memory from disk and runs when you turn on
    your computer
  • UNIX-type of systems were among the first to
    include a hierarchical file system
  • UNIX-type of systems support multiple file system
  • UNIX-type of network file systems include NFS and

Summary (continued)
  • Consult the commands manual (man) page by typing
    man command at the shell prompt, and pressing
    Enter to learn more about a command
  • ls command is most frequently used command
  • The useradd and groupadd commands allow you to
    add new users and groups
  • The chgrp and chmod commands assign files to
    groups and change file access permissions

Summary (continued)
  • Installing the Samba application on a UNIX-type
    of server allows it to exchange information with
    Windows servers by using Windows file system and
    file access protocols
  • All modern flavors of UNIX, Linux, and Mac OS X
    Server support data sharing using directory
    services based on LDAP
  • Any client that runs the TCP/IP protocol can
    connect to a UNIX-type of host, such as a Linux
    server, through the Telnet utility