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

2. 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
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3. 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
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4. 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
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5. 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
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6. 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
Does not run on Macs
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7. 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
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8. 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
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9. 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
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10. 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?
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11. 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
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12. 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
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13. The UNIX Kernel Core of all UNIX-type of systems Kernel origins:
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
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14. 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
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15. 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
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16. A UNIX Command Sampler (continued)
Table 9-4: Commonly used UNIX commands
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17. A UNIX Command Sampler (continued)
Table 9-4 (continued): Commonly used UNIX commands
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18. A UNIX Command Sampler (continued)
Table 9-4 (continued): Commonly used UNIX commands
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19. 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
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20. A UNIX Command Sampler (continued)
Figure 9-3: Anatomy of ls –l output
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21. 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
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22. 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
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23. 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
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24. Establishing Groups and User on Mac OS X Server (continued)
Figure 9-4: User creation in Mac OS X Server’s Workgroup Manager
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25. 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
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26. 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
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27. Changing File Access Permissions on Mac OS X Server
Accomplished through the GUI
Must be logged on as system administrator
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28. 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
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29. 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
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30. 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
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31. 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
Network+ Guide to Networks, 4e