Figure 4.1 The NTFS file system enables a network administrator to control access to files and folders on Windows NT and Windows 2000 drives.
In the past, there was a significant difference between a standalone operating system and a network operating system. The typical operating system provided no networking capabilities, and you had to purchase and install networking software to run on it. Today, virtually all operating systems are network operating systems, because they include, right in the box, the software needed to connect to a network. This lesson is concerned primarily with operating systems that provide server functions, although in some cases you can use the server system as a client or as a member of a peer-to-peer network as well.
All Windows operating systems except Windows NT and Windows 2000 are built on the MS-DOS kernel. Windows NT 3.1, first released in 1993, was a radical departure from the MS-DOS tradition. It was newly designed from the ground up to support an entirely different memory architecture and to integrate networking capabilities into the operating system itself. Windows NT and Windows 2000 also offer preemptive multitasking, which enables the system processor to run multiple programs simultaneously without relying on the programs themselves to return control to the processor. In the years since the original release, Microsoft has released several relatively minor Windows NT upgrades, culminating in version 4.0, and then finally released Windows 2000, which was a major upgrade.
Windows NT and Windows 2000 have always existed in versions intended both for servers and for client workstations. Windows NT is available in Server and Workstation versions, and Windows 2000 is available in three Server versions (Server, Advanced Server, and Datacenter Server) for systems with various numbers of processors, and a Professional version for client workstations. The underlying kernels of both server and workstation versions are essentially identical; the difference between the two is that the server version includes a large collection of additional programs, services, and utilities designed for server use, many of which are concerned with networking. The following sections examine some of these components and how they affect the networking capabilities of the operating systems.
Sharing files is one of the main reasons for networking computers, and all network operating systems include a service that makes file sharing possible. One of the most important elements of file sharing is the ability to restrict access to the server files. Windows NT and Windows 2000 both include a file system called NTFS (the NT file system) that is specifically designed for this purpose. The MS-DOS–based versions of Windows use the File Allocation Table (FAT) file system, and Windows NT and Windows 2000 support FAT, too. You can share FAT drives with other users on the network, but the FAT file system's security capabilities are extremely limited. When you create NTFS drives during a Windows NT or Windows 2000 installation, you can specify access permissions for specific files and folders to the users and groups on your network with great precision, using the controls shown in Figure 4.1. NTFS also supports larger amounts of storage than do FAT drives.
For example, if you store your company's accounting spreadsheets on a Windows NT or Windows 2000 NTFS drive, you can grant the bookkeepers full Read/Write access to the files, grant Read-only access to other company executives, and prevent any other users from even seeing that the files exist. Maintaining these permissions is an important part of the network administrator's job.
In Windows NT and Windows 2000 terminology, a service is a program that runs continuously in the background while other operations are running at the same time (see Figure 4.2). Most of the networking capabilities in Windows NT and Windows 2000, and particularly the server functions, are provided by services. In most cases, you configure services to load when the system boots, and they remain loaded and running even when users log on and log off the computer.
The following services are the core of the operating system's networking capabilities:
The following services are optional, but provide important networking support:
Security is a primary concern on larger networks, and Windows NT and Windows 2000 provide a much more comprehensive security model than do the MS-DOS-based versions of Windows. Windows NT Server and Windows 2000 Server systems have the ability to function as domain controllers, which store information about accounts and other network resources, for access by clients anywhere on the network. Using domain controllers instead of individual computers to store security information makes it easier for network administrators to control access to network resources. For more information about domain controllers, see Lesson 3: Directory Services, later in this chapter.
Novell NetWare was the first commercially successful network operating system, and while its popularity has largely been eclipsed by Windows NT and Windows 2000, it still remains a viable networking platform. NetWare is strictly a client/server operating system, unlike Windows NT and Windows 2000, which can function as both clients and servers. This means that you cannot use a NetWare server to access shared resources on other computers or run workstation applications. The NetWare operating system is not DOS-based (although it loads from a DOS prompt), and is dedicated solely to server operations. NetWare clients communicate only with NetWare servers, and not with each other. To transfer files from one workstation to another, for example, you must copy them from the first workstation to a server, and then from the server to the other workstation.
NetWare is available in two primary versions, 3.2 and 5.1. Version 3.2 was intended to be the final release of the original NetWare product that stores user account information in a simple flat database called the bindery. The bindery was replaced by Novell Directory Services (NDS) in NetWare version 4.0 (released in 1993), but Novell continues to develop and market the 3.x version because it has a large installed user base that does not need the more advanced capabilities of NDS, and these users have no plans to upgrade their networks. Version 5.1 is the current release of the NDS-based NetWare product that began with version 4.0.
NetWare is a network operating system that was originally designed primarily to provide clients with access to file and print services, and these remain NetWare's strengths. As a network application platform, NetWare trails behind both Windows and UNIX, and there is currently relatively little application development for NetWare.
Because they do not have to perform workstation operations, NetWare servers have a relatively simple, character-based interface, as shown in Figure 4.3. There is no need for a graphical interface on a server (although the most current versions have an optional Java-based interface called ConsoleOne that you can use), and as a result, the computer can devote less of its resources to maintaining a graphical display and more to performing its server functions.
Like Windows NT and Windows 2000, NetWare has its own file system that enables you to control access to the server resources with great precision. You can assign access permissions based on either bindery accounts or NDS objects, depending on which version of NetWare you are using. The NetWare file system consists of volumes that you create on server drives. By adding specialized components called name space modules, you can create NetWare volumes that support various client file systems, such as Windows Virtual File Allocation Table (VFAT), Macintosh, and Network File System (NFS). This enables clients to store their files on NetWare servers using their own native formats.
When NetWare was first developed in the mid-1980s, networking was more of a proprietary venture, and interoperability between products made by different manufacturers was less of a concern than it is today. Novell, therefore, developed their own set of networking protocols, which have come to be named after the main network layer protocol, called Internetwork Packet Exchange (IPX). Unlike Windows NT, Windows 2000, and UNIX, which have long since adopted TCP/IP as their native protocols, NetWare still relies heavily on IPX. Fortunately, Microsoft has developed its own protocol, called NWLink, to be compatible with IPX. All of the Windows operating systems can use NWLink to access shared NetWare resources.
In addition to its core file and print services, which have been present since the early days of NetWare, the latest versions include many other additional services, such as the following:
UNIX is a network operating system that was originally developed in the 1970s, and is now available in dozens of different versions and variants. Unlike Windows and NetWare, UNIX is not the product of one particular company. A variety of different development teams worked on their own UNIX versions during the ensuing decades, which were released under many different names, including the following:
The UNIX operating systems are built around the TCP/IP protocols, and while all have certain similarities, they vary greatly in their capabilities. This is due to the variations in the additional software included with the operating system and the commercial (or non-commercial) nature of the various products. Some UNIX variants are commercial products marketed by large software companies, such as Hewlett Packard, Sun Microsystems, and IBM. Others are developed and maintained as part of the open source movement, in which volunteer programmers work on the software in their spare time, usually communicating with their colleagues over the Internet, and freely releasing their work to the public domain. There are many different UNIX operating systems that you can download from the Internet free of charge, such as FreeBSD, NetBSD, and various forms of Linux.
This non-commercial side of UNIX development is based on the fact that many of the development teams freely post the source code for the operating system. Users with programming expertise then modify the code to suit their particular needs and post the revised code for use by others. This is in stark contrast to companies like Microsoft and Novell, who zealously guard the source code for their operating systems.
UNIX is primarily an application server platform, and is typically associated with Internet services, such as Web, FTP, and e-mail servers. As with Windows NT and Windows 2000, UNIX systems can function as both servers and clients at the same time. While you can use UNIX as a general purpose LAN server, it is much more difficult to install and administer than either Windows or NetWare. There are UNIX programs that provide the file and print services needed by LAN users, such as the NFS and the Line Printer Daemon (LPD), but they are far from being as easy to use as their Windows NT, Windows 2000, and NetWare equivalents. NetWare's strength is in file and print services, while the strength of UNIX is in its network application capabilities. Windows NT and Windows 2000 fall somewhere between the two, fulfilling both roles but doing neither as well as the more specialized operating systems.
UNIX, in general, is a less intuitive operating system than either Windows or NetWare. Although many UNIX variants now include graphical user interfaces (GUIs), UNIX is still primarily a character-based platform, and the command interface requires a good deal of study and practice to use efficiently. While a relatively unsophisticated user can install a Windows NT, Windows 2000, or NetWare server and get it running without too much trouble, the same cannot be said for the typical UNIX operating system.
Match the network operating system in the left column with the phrase in the right column that best describes it.
1. Linux |
a. Uses a bindery to store user accounts |
2. Windows NT |
b. Current version of the original AT&T UNIX |
3. UNIX System V |
c. Available in Server, Advanced Server, and Datacenter versions |
4. NetWare 3.x |
d. First version of Windows not based on MS-DOS |
5. Windows 2000 |
e. Open source UNIX version |