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

Network+ Guide to Networks, 4e2 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

Network+ Guide to Networks, 4e3 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

Network+ Guide to Networks, 4e4 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

Network+ Guide to Networks, 4e5 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

Network+ Guide to Networks, 4e6 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

Network+ Guide to Networks, 4e7 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

Network+ Guide to Networks, 4e8 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

Network+ Guide to Networks, 4e9 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

Network+ Guide to Networks, 4e10 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

Network+ Guide to Networks, 4e11 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

Network+ Guide to Networks, 4e12 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?

Network+ Guide to Networks, 4e13 Solaris Hardware Requirements Table 9-1: Minimum hardware requirements for Solaris 10

Network+ Guide to Networks, 4e14 Linux Hardware Requirements Table 9-2: Minimum hardware requirements for a Linux server

Network+ Guide to Networks, 4e15 Mac OS X Server Hardware Requirements Table 9-3: Apple hardware recommendations for Mac OS X Server

Network+ Guide to Networks, 4e16 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

Network+ Guide to Networks, 4e17 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

Network+ Guide to Networks, 4e18 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

Network+ Guide to Networks, 4e19 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

Network+ Guide to Networks, 4e20 UNIX System File and Directory Structure (continued) Figure 9-1: UNIX file system hierarchy

Network+ Guide to Networks, 4e21 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

Network+ Guide to Networks, 4e22 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

Network+ Guide to Networks, 4e23 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

Network+ Guide to Networks, 4e24 A UNIX Command Sampler (continued) 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

Network+ Guide to Networks, 4e25 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 “/”

Network+ Guide to Networks, 4e26 A UNIX Command Sampler (continued) Table 9-4: Commonly used UNIX commands

Network+ Guide to Networks, 4e27 A UNIX Command Sampler (continued) Table 9-4 (continued): Commonly used UNIX commands

Network+ Guide to Networks, 4e28 A UNIX Command Sampler (continued) Table 9-4 (continued): Commonly used UNIX commands

Network+ Guide to Networks, 4e29 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

Network+ Guide to Networks, 4e30 A UNIX Command Sampler (continued) Figure 9-3: Anatomy of ls –l output

Network+ Guide to Networks, 4e31 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?

Network+ Guide to Networks, 4e32 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

Network+ Guide to Networks, 4e33 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

Network+ Guide to Networks, 4e34 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 groups –-g option specifies initial group –-G option specifies additional groups

Network+ Guide to Networks, 4e35 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

Network+ Guide to Networks, 4e36 Establishing Groups and User on Mac OS X Server (continued) Figure 9-4: User creation in Mac OS X Server’s Workgroup Manager

Network+ Guide to Networks, 4e37 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

Network+ Guide to Networks, 4e38 Changing File Access Permissions on Linux and Solaris 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

Network+ Guide to Networks, 4e39 Changing File Access Permissions on Mac OS X Server Accomplished through the GUI Must be logged on as system administrator

Network+ Guide to Networks, 4e40 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

Network+ Guide to Networks, 4e41 Connecting to UNIX-Type of Servers (continued) 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

Network+ Guide to Networks, 4e42 Connecting to UNIX-Type of Servers (continued) Figure 9-5: Windows Telnet session

Network+ Guide to Networks, 4e43 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

Network+ Guide to Networks, 4e44 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

Network+ Guide to Networks, 4e45 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

Network+ Guide to Networks, 4e46 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