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Network+ Guide to Networks, Fourth Edition

Chapter 9 Networking with UNIX-Type of Operating Systems. Network+ Guide to Networks, Fourth Edition. Objectives. Describe the origins and history of the UNIX operating system Identify similarities and differences between popular implementations of UNIX

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Network+ Guide to Networks, Fourth Edition

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

  2. Objectives • Describe the origins and history of the UNIX operating system • Identify similarities and differences between popular implementations of UNIX • Describe the features and capabilities of servers running Solaris, Linux, and Mac OS X Server • Explain and execute essential UNIX commands

  3. Objectives (continued) • Install and configure Linux on an Intel-based PC • Manage users, groups, and file access permissions in Solaris, Linux, and Mac OS X Server • Explain how computers running other operating systems can connect to UNIX servers

  4. 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 AT&T) • System V • UNIX source code was cheaply available from AT&T • Quickly distributed to many organizations

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

  6. 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 programs • Start programs without interfering running programs

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

  8. 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 servers • AIX: IBM • Runs on PowerPC-based computers • Does not run on Macs

  9. Proprietary UNIX (continued) • Advantages: • Accountability and support • Optimization of hardware and software • Predictability and compatibility • Customer has no access to system’s source code • Cannot customize

  10. 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

  11. 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 Apple’s Xserve line of computers as well as Power Mac computers • All support TCP/IP and other protocols • Support many network topologies and physical media

  12. 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?

  13. Solaris Hardware Requirements Table 9-1: Minimum hardware requirements for Solaris 10

  14. Linux Hardware Requirements Table 9-2: Minimum hardware requirements for a Linux server

  15. Mac OS X Server Hardware Requirements Table 9-3: Apple hardware recommendations for Mac OS X Server

  16. A Closer Look at 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

  17. 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

  18. The UNIX Kernel • Core of all UNIX-type of systems • Loaded into memory and runs computer turned on • Coordinates access to computer’s hardware • Can add or remove functionality by loading and unloading kernel modules • Files containing instructions for performing specific tasks • Kernel origins: • Solaris: original AT&T UNIX software • Linux: Linus Torvalds • Mac OS X Server (XNU): Mach

  19. UNIX System File and Directory Structure • First OSs to implement hierarchical file system • /boot directory contains kernel and other system initialization files • Applications and services stored in /bin and /sbin directories • /var directory holds variable data • Users’ login directories typically in /home • /Users on Mac OS X Server

  20. UNIX System File and Directory Structure Figure 9-1: UNIX file system hierarchy

  21. UNIX System File Services • Disk File Systems: • OS’s 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

  22. 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

  23. A UNIX Command Sampler • Command line is primary method of interacting with UNIX-type systems • Command interpreter (shell): program that accepts and runs typed commands • Primary UNIX command interpreter file is /bin/sh • Every UNIX-type system contains full documentation of UNIX commands in manual pages (man pages) • Access via man command

  24. A UNIX Command Sampler • Nine man page sections: • Section 1 covers commands most typically entered • Sections 2 through 5 document programmer’s interface to UNIX system • Section 6 documents some amusements and games included in UNIX system • Section 7 describes device drivers • Section 8 covers commands used by administrators to manage system • Section 9 documents UNIX kernel functions programmers use when writing device drivers

  25. A UNIX Command Sampler (continued) • apropos command: find possible manual page entries for a command • Most commands are lowercase alphabetic characters • To specify an option, usually type a hyphen (-) followed by a letter • File globbing: equivalent to using wildcards in Windows and DOS • UNIX directory separator character is “/”

  26. A UNIX Command Sampler (continued) Table 9-4: Commonly used UNIX commands

  27. A UNIX Command Sampler (continued) Table 9-4 (continued): Commonly used UNIX commands

  28. A UNIX Command Sampler (continued) Table 9-4 (continued): Commonly used UNIX commands

  29. 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 (i-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

  30. A UNIX Command Sampler (continued) Figure 9-3: Anatomy of ls –l output

  31. Installing Linux: Planning a Linux Installation • Be prepared to answer following questions: • What is the new server’s name? • What is the server’s IP address? • Also need subnet mask, IP address of server’s primary gateway, and IP address of new server’s domain name server • What kind of video card is installed in the server? • What is the administrative user’s password? • Root: administrating user name • How can this information be remembered?

  32. Installing and Configuring Fedora Core • Installation tasks: • Select language • Confirm keyboard layout • Select Server installation type • Select disk drive partitioning options • Choose booting options • Configure the network interface(s) • Configure firewall and security level options • Set the time and time zone • Enter the root password

  33. 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 application

  34. Establishing Groups and Users (Linux) • 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 groups • -g option specifies initial group • -G option specifies additional groups

  35. Establishing Groups and User (Mac OS X) • Use Workgroup Managerapplication • Creating new group does not assign users • Assign unique name and numeric ID to groups

  36. Establishing Groups and User (Mac OS X) Figure 9-4: User creation in Mac OS X Server’s Workgroup Manager

  37. 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 directory’s owner

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

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

  40. Connecting to UNIX-Type of Servers • UNIX-type of systems and Windows can both communicate via TCP/IP • File systems not necessarily compatible • Samba: one application that bridges file system incompatibility • Provides networking services necessary to make a UNIX-type system a fully featured Windows file- and printer-sharing server • Communicates with Windows servers using SMB file-sharing protocol and CIFS protocol

  41. Connecting to UNIX-Type of Servers • All modern flavors of UNIX, Linux, and Mac OS X Server support data sharing using directory services based on LDAP • Solaris: Sun Java System Directory Server Enterprise Edition • Linux: OpenLDAP • Mac OS X Server: Open Directory • UNIX-type of systems include full complement of Internet tools • e.g., Telnet

  42. Connecting to UNIX-Type of Servers Figure 9-5: Windows Telnet session

  43. Summary • 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

  44. 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 types • UNIX-type of network file systems include NFS and Samba

  45. Summary (continued) • Consult the command’s 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

  46. 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

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