Chapter Ten
Networking
with UNIX
Brief History of UNIX
System V (1960’s)


Versions of UNIX that come from Bell Labs
Antitrust law prohibited sale
BSD (Berkeley Software Division)


Versions of UNIX from researchers at the University of
California at Berkeley
Added TCP/IP
Caldera International and Tarantella jointly own the
rights to the UNIX source code
The Open Group owns the UNIX trademark
Common UNIX Features
The ability to support multiple, simultaneously
logged in users
Hierarchical file systems that incorporate
demountable volumes
Consistent interfaces for input of data to and
output of data from hardware devices, files,
and running programs
The ability to start processes in the
background
Common UNIX Features
Hundreds of subsystems, including
dozens of programming languages
Program source code portability
Windows interfaces that the user can
configure, the most popular of which is the
X Window system
Current State of the Market
Unix market is huge and highly segmented
Some real-time implementations of the
UNIX system exist


In a real-time implementation, the operating
system must respond to input immediately
NASA – space shuttle & international space
station
Two major UNIX market segments


Proprietary
Open source
Proprietary UNIX
An implementation of UNIX for which the
source code is either unavailable or
available only by purchasing a licensed
copy from Caldera International and
Tarantella



Sun’s proprietary version of UNIX is called
Solaris (for SPARC-based workstations)
IBM’s proprietary version of UNIX is called AIX
HP’s proprietary version of UNIX is called HPUX
Choosing a Proprietary UNIX System
Advantages



Accountability and support
Optimization of hardware and software
Predictability and compatibility
Drawback

Customer has no access to the system’s
source code and thus cannot create a custom
solution
Open Source UNIX
Open source software


Software developed and packaged by a
few individuals and made available to
anyone without licensing fees
Also called freely distributed software
UNIX-like systems in this category include
GNU, FreeBSD, and Linux
Different implementations of UNIX-like systems
are known as flavors

Linux – RedHat, Caldera, & Mandrake
Open Source UNIX


Freely distributable versions of UNIX
include a copyright called the General
Public License (requires the source code
to be made available to anyone receiving
the system)
1991 - Linus Torvalds (then a 2nd year
Finnish computer science student)
developed Linux
Choosing UNIX
UNIX supports TCP/IP, IPX/SPX and
AppleTalk protocols
UNIX supports Ethernet, Token Ring,
FDDI and wireless LANs
Choosing UNIX
Samba


Open source software package
Complete Windows 2000-style file and print
sharing facility
UNIX was originally developed as a time-
sharing system

Computing system to which each user must
attach directly to share the resources of that
computer (dumb terminal)
Some proprietary UNIX systems have
received Orange Book certification

U.S. DOD certification
UNIX Server Hardware
Base system unit must include:




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Motherboard with CPU, memory, and I/O
control
Network interface card (NIC)
Floppy disk drive
CD-ROM drive
One or more fixed disks
Decisions in Choosing
Hardware
Table 10-1:
Typical
hardware
requirements
for a Linux
server
A Closer Look at Linux
Linux multiprocessing

Supports symmetric multiprocessing (SMP)
Linux memory model

From its inception, Linux was created to use
both physical and virtual memory efficiently
Linux Kernel
Kernel


As in NetWare, is the core of the system
Also similar to NetWare, it is possible to add
or remove functionality by loading and
unloading Linux kernel modules
Similar to NetWare NLMs
Linux File and Directory
Structure
Hierarchical file system

Organization of files and directories on a disk partition in which
directories may contain files and directories
FIGURE 10-1
Linux file
system
hierarchy
Linux File Services
Linux includes support for multiple types of file
systems, including:





Local file systems
Remote file systems – map to Windows or NetWare
Servers
Its native file system, called ext2 (second extended)
Can access FAT & NTFS (read-only) file systems
Sun Microsystem’s Network File System (NFS)
Linux Internet Services
and Linux Processes
Linux Internet Services


First browsers and servers were developed
on UNIX
Apache
Open source software application that is the
leading Internet Web server
Linux Processes

Another UNIX innovation is the notion of
separate, numbered processes
Linux Command Sampler
Command interpreter



Program that accepts your typing and runs
the command
Also known as a shell
Keeps track of the command history, much
like the doskey command in DOS and
Windows 2000
Linux Command Sampler
Globbing


Form of filename substitution
Similar to using wildcards in Windows/DOS
Pipe

Serves as the connection between two
commands
Pipeline

Two or more commands separated by a pipe
Linux Command Sampler
TABLE 10-2a: Commonly used Linux commands
(p. 493)
Linux Command Sampler
TABLE 10-2b:
Commonly used
Linux commands
(cont.)
Linux Command Sampler
Linux systems keep quite a bit of information
about each file, including:


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
Filename
File size (in bytes)
Date and time a file’s i-node (file information
node) was created
Date and time that the file was last accessed
Date and time that the file contents were last
modified
Linux Command Sampler
Information Linux system keeps about each
file (cont.):




Number of “aliases” or links to the file
Numeric identifier of the user who owns the file
Numeric identifier of the group to which the file
belongs
Access rights for the owner, the group, and all
others
Linux Command Sampler
To learn about the i-node information, use the ls command
Figure 10-2:
Example of
output from
ls
Linux Preinstallation Questions
Linux very peacefully coexists with other
operating systems on your primary hard drive
Read more about multiboot systems at the
Linux installation HOWTO site:

http://www.linuxhq.com/ldp/howto/InstallationHOWTO/index.html
Internetworking with Other Network
Operating Systems
Samba – Windows file & printer sharing
IPX/SPX
AppleTalk
X3270 – mainframe access
WINE – Win32 programming subsystem
VMWare – emulate Intel-based computer
Dozens and dozens of command-line utilities
that enable access to contents of files generated
on other systems