Transcript Computer Networks

Network Operating Systems :
Tasks and Examples
Instructor: Dr. Najla Al-Nabhan
2014
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Lecture Outline
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NOS Examples:
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This Lecture:
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(Windows 95, and windows for workgroups)
Windows NT Server
Novell NetWare
UNIX/LINUX
MAC OS AppleShare
Windows NT Server
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Windows NT Server was first introduced in the mid-90s
and is capable of managing workgroups just like Windows
for Workgroups/95.
Windows NT Server has all of the advantages mentioned
for the other Windows operating systems, plus, it contains
several other features making it more robust.
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Windows NT Server
Features:
1. It is a client/server NOS that uses routable protocols,
making it a true Internetworking Operating System
enabling network administrators to connect LANs to
WANs.
2. Windows NT Server also provides services for OS/2
and Novell NetWare clients
3. It is able to run on various microprocessors such as
Intel Pentium, DEC Alpha, RISC, MIPS, and PowerPC
based systems.
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Windows NT Server
Features:
4. The security on Windows NT allows a network
administrator to not only provide passwords for
resources but also to individuals or groups.
5. This operating system does require the use of a
more powerful server computer whose sole
function is to act as administrator of the NOS program.
6. Having a server where all access data is stored makes
managing Windows NT Server Operating Systems
efficient.
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Security in Windows NT Server
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Windows NT Server has more than one level of security
beyond access/no access. This NOS offers:
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no access.
access that restricts the user to read only capabilities.
access that allows read and write usage.
access that allows you to change access permissions for
network users.
Each user who wishes to access services on the network
must have a password and a user account set up within
the domain.
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Security in Windows NT Server
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Domain:
A domain is a security model where the database of user
accounts is stored on one or more computers known as
domain controllers.
Important for the centralize control of the network.
The network administrator creates, deletes, and manages
these accounts and passwords using the User Manager for
Domains program that comes with Windows NT Server.
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Security in Windows NT Server
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For security reasons, companies often have two servers capable of
authenticating passwords:
 one that acts as the Primary Domain Controller (PDC) and
 the other as the Backup Domain Controller (BDC).
PDC:
 The PDC is a computer on the network that maintains a
database of users and security policies for the domain. This
database contains the names of users and the resources they may
access. User access may be defined for individual files or for
entire directories.
 Note that although the PDC is often a server computer, this is
not necessary. Network services can be implemented on one
computer and the PDC functions on another
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Security in Windows NT Server
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BDC (Backup Domain model) :
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A BDC maintains a copy of the PDC database. This backup
database prevents network disruption in the event of failure of
the PDC.
If a failure occurs, the backup domain controller can be easily
switched to the PDC.
With Windows NT Server networks can connect to other
domains.
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are four basic domain models:
Windows NT Domain Models
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Single Domain Model— In the single domain model,
there is only one defined set of security and user
accounts. This means that all management functions are
centralized.
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Windows NT Domain Models
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Master Domain Model— In this model, there is one
master domain server that has the defined set of security
and user account data of all other domain servers.
However, each of these has only the specific security data
for one domain. A user on one domain cannot get
permissions not found on her/his domain server. This
improves on the single domain model since it allows
segmentation of networks, which increases security
measures, yet still allows centralized management of
network user accounts and accessibility.
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Windows NT Domain Models
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· Multiple Master Domain Model—The Multiple
Master Domain Model has several master domain
servers, each with their own specific domains. In this
model, network management becomes somewhat
decentralized and network administrators cannot maintain
the entire network from one central domain server.
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Windows NT Domain Models
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Multiple Trust Domain Model— This model is really a
peer-to-peer relationship among domain servers,
therefore it becomes decentralized and security is
essentially the same as with Windows for Workgroups and
Windows 95.
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Novell NetWare Operating Systems
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Novell NetWare Operating Systems, also a client/server
based NOS, is not domain based but binary based.
It has evolved over time from NetWare 2.X, now
obsolete, which was designed for small workgroup
environments to NetWare 5.X that is aimed at global
enterprise network environments.
NetWare is optimized for managing, sharing, translating,
and synchronizing information throughout the networkcomputing environment
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Features of Novell NetWare
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Novell NetWare 4.X features NetWare Directory
Services (NDS), which allows a user to logon from
anywhere on the network and access the same resources
regardless of where the user logs on.
This product has become Novell’s migration strategy for
the future.
Novell NetWare does not actually provide a computer
operating system for client workstations; it supplies an
operating system for a dedicated server computer, and
networking support to existing client workstation
operating systems.
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UNIX/LINUX
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UNIX is the oldest network operating system still being
widely used today.
It can be used on either peer-to-peer or client/server
networks.
LINUX is basically a free version of UNIX, which is
developed cooperatively by a community of expert
programmers.
Various computer manufacturers have released
proprietary versions of UNIX which run on their
particular hardware platforms.
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UNIX/LINUX
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Because of differences in processor hardware and
variations from UNIX standards, each company’s
operating system has its own “flavor”.
End user applications for UNIX must be individually
compiled for each different hardware platform and
operating system variant.
The networking components in UNIX have been under
development for many years, and are based on the
collaborative efforts of many developers.
Consequently, UNIX networking is extremely reliable.
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UNIX/LINUX
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Because of UNIX security, many companies use UNIX to
provide their primary networking services and interface
to the Internet.
In spite of the rise in popularity of Web and Internet
services deployed on Windows NT, for security and
reliability UNIX is a popular choice in commercial and
university environments.
Networking under UNIX is based on the TCP/IP
protocol, which has only been integrated into the
Microsoft Windows NOSs in recent years.
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The early work, which established the Internet, was based on
UNIX platforms. Most of the TCP/IP services used in UNIX are
also commonly used on.
UNIX vs. Microsoft Windows OS
Microsoft Windows operating systems, with a few
exceptions:
1- Network File System (NFS)—
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NFS provides hard disk sharing over TCP/IP networks.
It is the primary file and directory sharing protocol used
in UNIX.
NSF clients are available for Microsoft Windows operating
systems, but are generally used for interoperation with
UNIX hosts.
UNIX vs. Microsoft Windows OS
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2- Remote login services (RLOGIN and TELNET)—
UNIX has always been a truly multi-user multi-session
operating system.
Multitasking of applications and processes is extremely robust;
much more so than under Windows NT.
In addition many users can run private sessions simultaneously
under UNIX, by logging in to a host using a character-based
terminal or emulated terminal over a serial or network
connection.
RLOGIN and TELNET protocols support logging in over
network connections.
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UNIX vs. Microsoft Windows OS
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Graphical user interface windowing system (X
Windows)—
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X-Windows is a completely distributed graphical user interface
system.
Using X-Windows, a user can execute an application on one computer,
and let that application interact with a user on a different computer,
using a network connection.
X Windows allows computers to share their video displays, keyboards
and pointing devices with applications running on other computers.
There is no requirement that the application execution and display
hosts even have the same type of hardware or run the same operating
system, as long as the client application and the display server support
the X Windows protocol.
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UNIX vs. Microsoft Windows OS
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Graphical user interface windowing system (X
Windows)—
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Windows NT has recently included support for graphical sessionbased terminal servers that offer some similar functionality to X
Windows, but with much less flexibility.
In addition, X Windows server software is available for Microsoft
Windows operating systems, allowing applications running on UNIX
hosts to be displayed on computers running Microsoft Windows
operating systems.
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MAC OS AppleShare
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AppleShare provides network services for the Mac OS
operating systems.
AppleShare supports file and printer sharing over
several types of physical networks by using one of the
AppleTalk transport protocols:
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LocalTalk, EtherTalk, TokenTalk or FDDITalk.
As the Internet has grown in popularity, TCP/IP
software has been developed for the Apple MacIntosh
computers, along with the standard TCP/IP client
applications like Web Browsers and FTP file transfer
clients.
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MAC OS AppleShare
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AppleShare’s peer-to-peer networking is used in small
or moderately sized workgroup settings, but has not
been adopted widely in large-scale corporate LAN
environments.
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Check Your Understanding
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What are the advantages and disadvantages of Windows for
Workgroups/95?
What are some of the features added to Windows NT Server
that are not supplied for Windows for Workgroups/95?
What are some differences between NetWare and Windows
NT Server?
How has the popularity of the Internet affected network
support in Mac OS and the Microsoft Windows operating
systems?
Which family of operating systems has traditionally supported
TCP/IP and internetworking?
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Midterm
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next lecture
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