Major Nework Operating Systems Compare/Contrast

 

 

The most important software on a network is the Network Operating System (NOS).  The NOS organizes and manages all the activities on a network.  Networking operating systems, offered by companies such as Microsoft and Novell, are actually a combination of programs that give some computers and peripherals the ability to accept request for service across the network and give other computers the ability to correctly use those services.  Servers are computers that share their hard-disk drives, attached peripherals such as printers and CD-ROM drives, and communications circuits. Servers inspect request for proper authorization, check for conflicts, and then provide the requested service.  Some of the major NOS are Linux, Unix, Windows NT, Novell, and Solaris.  Each has it’s strengths and weaknesses.

 

Microsoft Windows NT 4

 

Primary market for NT is the PC platform controlled by a single vendor (Microsoft)--all versions of NT share the same APIs and system calls; most NT applications are multithreaded.  NT is available on multiple platforms (x86 and Alpha); standardized APIs mean that porting to another NT version means a simple recompilation.   Software vendors strongly support NT, resulting in a large software library.  It is driven by relatively easy-to-use GUI utilities Standardized GUI and offers both a NOS and application server solution out of the box.  However, NT has some weaknesses. NT is tied to PC platform available for Digital Alpha, but most applications focus on the dominant PC market. Scalability is largely driven by the Intel architecture.  It lacks solid scripting utilities and character-based apps.  Managing an NT server remotely requires specialized GUI utilities Severely restricted functionality, if limited to a character-based interface.  It’s Directory Services are Limited to NT domains, which don't tie into non-NT networking.

Microsoft created Windows NT as a 32-bit operating system with advanced multitasking capabilities. It came with two versions: Workstation and Server. The first versions (3.1, 3.5, and 3.51) of NT, which stands for New Technology; had the same GUI (graphical user interface) as Microsoft Windows 3.1.  The new technology that NT came with was behind the scenes and was evident in NT’s multitasking capabilities.  Windows NT 4 uses the same GUI as Windows 95.  Windows NT uses a logical organizational scheme called domains for its computers and users This scheme is similar to a workgroup organization. Each computer is designated as a member of a domain. Each user is created as a member account of the domain.  The domain requires a special computer, called a primary domain controller (PDC), to maintain the database of users and computers that are members of the domain.  There can be only one PDC per domain. Additional domain controllers, called backup domain controllers (BDCs), can be installed into the domain to provide a measure of redundancy.  When the primary domain controller is down, the backup domain controller authenticates users so that they can access network resources such as files and printers. The backup domain controller cannot be used to create new users in the domain.  If the primary domain controller fails or is removed from the domain for another reason, a backup domain controller can be promoted to primary domain controller so that it can be used to create new users.  The primary domain controller maintains security information for the users and computers. This information is located in the SAM (Security Account Manager) database, which is located on the PDC and replicated on the BDCs, if there are any.  An internetwork can have multiple domains, but multiple domains make security more complex. Each primary domain controller has its own security database (the SAM). If the users of one domain need to access resources available on computers that are members of another domain, the standard separate domain configuration will not work. Therefore, Microsoft uses a trust relationship to overcome this issue. The trust relationship can enable a single authenticated logon for a user to access any resource in any domain if that user has been granted access to it.

A single trust relationship creates one-way access Therefore, for two domains to have access to each other, two trust relationships must be set up. Domain A must trust Domain B, and Domain B must trust Domain A. A trusting- relationship is created so that users can access network resources in another domain. This access includes being able to log on to computers in the other domain.  Without the right trust relationship, the users’ domain will not even appear in the logon screen.  The main drawback to domains is the precise planning required. Domains tend to be difficult to rename or redefine.  A change at that level is typically done only through reinstalling software and manually changing each member server’s and workstation’s domain membership.  Because changes are so problematic, you should create a domain plan before implementing Windows NT. This plan should also take into account the growth of the enterprise and potential changes, such as mergers or migrations. The NT groups are confusing to manage It is easy to just give up and grant rights to any group or any user that will accept them. Unfortunately, the result is that some people can access what they need to, others have more rights, and yet others have fewer.

 

Microsoft Windows 2000

 

Windows 2000 Server will support file, print, application, Web, and remote access services Application services are provided by a terminal service that enables client computers to run Windows graphical terminal emulation of the server at their desktops.  The planned releases of the Windows 2000 Server series will include SMP (symmetrical multiprocessing) support.  To relieve some of the clutter on the desktop, Microsoft moved the Administrative Tools, Scheduled Tasks, and Network and Dial-Up Connections icons to the Control Panel.  The new Troubleshoot button helps you diagnose a hardware problem straight from an applet in the Control Panel.  Windows 2000 Servers will run on machines containing up to two processors. Windows 2000 Advanced Server will work with machines running up to four processors. Servers equipped with Advanced Server can also be tied together in fail-safe clusters, under which one machine can cover for another in case of a breakdown. Windows 2000 Datacenter Server will be able to accommodate sixteen processors, much more memory, and will support clustered configurations.  Higher-level releases will also support clustering (using multiple redundant servers) and load balancing (being able to distribute connections and application loads across multiple servers).  The most important feature of this network operating system is the addition of an Active Directory Service.  The Active Directory Service is a distributed directory service of users, groups, computers, and other network resources. It offers a single point from which to administer the network.  It removes the separate domain structure with connecting trust relationships.  The Active Directory Service is a secured hierarchial tree of organizational units that can be organized in many ways.  The Active Directory Service simplifies network resource access for users, and it enhances administration capabilities for network administrators.  The Active Directory Service is similar to Novell Directory Services (NDS) and is based on the X 500 standard specification for directory services.

 

Novell NetWare

 

Novell NetWare, one of the first network operating systems, is one of the most popular.  It was originally created for the simple purpose of sharing hard-disk space.  The oldest versions are rare and are no longer supported.  Three versions of NetWare, which are 32-bit network operating systems, can be purchased today These versions are: NetWare 3.x, NetWare 4.x, NetWare 5.x.  Each version of NetWare has core features and services that are identical. What Novell NetWare does best is to provide file and print services to client Computers.  Additional services are run as NLMs on NetWare servers NLMs (NetWare Loadable Modules) are executables in the NetWare operating system.  NLMs are similar to daemons that run under Unix. NetWare otters extended file attributes and extensive rights access capabilities to files and directories. File attributes are applied to individual files.  Access rights can flow from a directory down through the directory structure and are applied to all the files within that structure.  The file attributes and access rights are the same across the various NetWare versions.  The main difference between versions is that the utilities used to apply file attributes and access rights in NetWare 3.x are command-line or DOS-menu based, and the utilities used in NetWare 4.x and 5.x is the NetWare Administrator.  File attributes are extended beyond standard DOS file attributes. Security access is different from a file attribute.  Security access is set on a file or directory for a specific user or group In NetWare 3.x, access rights are set in SYSCON In NetWare 4.x and 5.x, access rights are set in the NetWare.  Administrator Access rights can also be granted or revoked through the rights command, which is executed at the DOS command line. All versions of NetWare support multiple client types.  These client types include DOS, Windows 3.1, Windows For Workgroups 3.11, Windows 95, Windows 98, Windows NT, OS/2, Macintosh OS, and Unix.  A special file-system support enables the different operating systems to store and access files on the server. This file-system support is in the form of a namespace.  Namespaces are loaded onto a NetWare volume, which is a portion of the server hard disk or hardware RAID array and shared out to end users.  Novell developed the IPX (Internetwork Packet Exchange) protocol stack based on the XNS (Xerox Network System) protocols All versions of NetWare run on this proprietary protocol stack.  All versions of NetWare support the TCP/IP protocol stack, but NetWare 5 x runs TCP/IP as a native protocol. When older versions of NetWare run TCP/IP, they must also run IPX in order to function.  NetWare 5.x is unique in that it can run on TCP/IP alone.  Novell created a group of network management tools called Z.E.N.works (Zero Effort Networks).A reduced set of Z.E.N.works tools ships with NetWare 5.x.  Z.E.N.works is completely integrated into the NDS tree and extends the capabilities of the NetWare Administrator program.  New objects, such as workstation objects, appear in the tree so that the administrator can manage a network inventory.  Novell developed a new printing system in partnership with Xerox and Hewlett-Packard.  This printing system takes advantage of 32-bit Windows printing architecture and extended printer capabilities.  This system is called Novell Distributed Printing Services, or NDPS.  NDPS enables end users to browse through their Network Neighborhood icons for printers.  After finding one, users can simply click on the icon to print to that printer. The NDPS printers are objects within the NDS tree, and security can be applied to prevent users from printing to inaccessible printers.

 

Unix

 

Unix has proven to scale in very large environments It is used on various hardware platforms, from workstations to supercomputers.  Forms of Unix have been in place for more than 20 years and offers a variety of software, development toolkits and utilities. Plenty of free software is available--particularly Internet services.  Unix is available on nearly every hardware platform (from PCs and RISC systems to mainframes). Unix is managed at a very low level through a character-based interface, making it easy to access all administrative functions remotely.  X Windows is network-enabled, letting any GUI utilities be accessed remotely and can be implemented in turnkey systems using simple GUI interfaces.  It Lacks a standard directory service, but products like NIS, NIS+ and DCE directory services integrate closely with the OS and offer Unix-specific schemas by default.  However, unix has it’s disadvantages.  More Unix vendors and incompatible versions of Unix than can be named in one article.  Applications written to one environment must be ported to another.  Most portable Unix apps are not multithreaded.  Unix is scalable, but high-performance RISC solutions are very expensive compared to PC hardware.  Complex OS requires experienced administrators.   Most versions have simplified installation processes and each vendor offers different management utilities. Unix is a peer-to-peer network operating system originally developed by Bell Laboratories for use on minicomputers It is unique because the original operating system was not proprietary There are many versions of Unix available today Each version is slightly different, but they all share the same core features and benefits.  The common element of Unix is the use of TCP/IP as the core protocol stack. The Unix environment allows both a peer-to-peer networking model and a server-based networking model.  Traditional Unix systems are hosts that provide user access through dumb terminals.  Unix has both a graphical interface and a text command-line interface.  Even when the graphical interface is used, a command-line window can be opened to enter Unix commands. Unix commands tend to be cryptic and awkward. For example, the command Ip is used to print a file. The commands also vary among different versions of Unix because they can have one of three different shells.  A shell is the command interface. The three types are Bourne, Korn, and C.  Several graphical user interfaces are available. The most popular are X-Windows and Motif, which function similarly to Microsoft Windows. The administration for a Unix server starts with the superuser or root account.  This account is named root and has the capability to override file permissions.  Each version of Unix has different types of administrative utilities, but the core of Unix administration lies in the configuration files located in the /etc directory.  The /etc/passwd file contains user information. To add a user account, the administrator can simply edit this file, The basic format of the file is that each row represents a user account. Each row contains fields that are separated by colons (:).

One of the configuration file that Unix servers contain is the /etc/hosts file The hosts file contains a table of hostnames mapped to their IP addresses.  The format of this file is:

#IP-Address hostname alias

127.0.0.1      localhost loghost

218.5.88.24      myserver

Services that Unix servers provide to the network are listed in the /etc/services file. The file maps the services with their port numbers and protocol. The format of the services file is:

#services port/protocol

ftp 21/tcp #File Transfer Protocol

telnet 23/tcp #Telnet

smtp 25/tcp #Simple Mail Transfer Protocol

tftp 69/udp #Trivial File Transfer Protocol

www 80/tcp #Hypertext transfer or World wide web

 

Linux

Linux, properly known as GNU/Linux, is a free, UNIX-like operating system, developed originally for home PCs, but which now runs on a variety of platforms including PowerPC, Macintosh, Amiga, Atari, DEC Alpha, Sun Sparc, ARM, and many others. Linux aims for POSIX compliancy to maintain maximum compatibility with other UNIX-like systems. With millions of users worldwide, Linux is probably the most popular UNIX-like OS in the world.  The central nervous system of Linux is the kernel, the operating system code which runs the whole computer. The kernel is under constant development and is always available in both the latest stable release and the latest experimental release. Progress on development is very fast, and the recent 2.2-series kernels are simply amazing on all counts. The kernel design is modular, so that the actual OS code is very small yet able to load whatever functionality it needs when it needs it, and then free the memory afterwards. Because of this, the kernel remains small and fast yet highly extensible, in comparison to other operating systems which slow down the computer and waste memory by loading everything all the time, whether you need it or not.  Linux systems excel in many areas, ranging from end user concerns such as stability, speed, and ease of use, to serious concerns such as development and networking. Nowadays, Linux even offers a variety of commercial productivity packages and office suites which can import and export files from other platforms, including Windows and MacOS.     In 1991, Linus Torvalds, at the time studying in Helsinki, Finland, created the very first version of Linux for his own needs.  Linux is offered in the form of distributions.  Linux is a multitasking, multiuser, and multiplatform NOS (network operating system), which means that it can run several applications for several different users and can be installed onto systems using different types of CPUs.  Linux is free and it can be redistributed at will and without cost, the source code is available, and it is modifiable by anyone sufficiently experienced in programming.  There are commercial applications for Linux that can be installed on a Linux server.  Linux supports several Unix file systems on local disks, including its own which provides for up to 4 terabytes of files and for file names of up to 255 characters.  Like all Unix operating systems, Linux includes complete TCP/IP protocol support.  Standard utilities are ftp, Telnet, and SNMP.  Linux has long been praised for its stability--Linux boxes are known for running months or even years at a time without crashing, freezing, or having to be rebooted. Linux users sometimes poke fun at other, less stable operating systems, by way of screensavers like BSOD (Blue Screen of Death, which displays crash screens from various other platforms) and games like XBill (where an evil virus masquerading as a popular operating system is causing machines to catch on fire).  Linux is Y2K-compliant, because it stores the date in a different way from other computers (its trouble date is 2038, by which time a small modification to the kernel should have solved the problem). Also, because it is extremely secure compared to other platforms, viruses for Linux essentially do not exist.  Linux machines are also known to be extremely fast, because the operating system is very efficient at managing resources such as memory, CPU power, and disk space. More of the Web than one might expect is actually powered by old 486 boxes running Linux and the Apache web server, while NASA, Scandia, Fermilabs and others have built very powerful yet inexpensive supercomputers by creating clusters of Linux boxes running in parallel.  As for an intuitive graphical interface, Linux has at least a dozen different highly configurable graphical interfaces (known as window managers) which run on top of XFree86, a free implementation of the X Window System. The most popular window managers at the moment are KDE (the K Desktop Environment) and GNOME (the GNU Network Object Model Environment). These offer the point-and-click, drag-and-drop functionality associated with other user-friendly environments (for example, Macintosh), but are extremely flexible and can take on a number of different looks and feels. If you want a Linux box running KDE to look just like a Mac, Windows, BeOS, or NextStep machine, you can do it with a few mouse clicks. Today, even complex tasks like system administration, package installation, upgrading, and network configuration can all be done very easily through graphical programs. Programs that work with one window manager nearly always work with all the others.  Networking comes naturally to Linux. After all, Linux is based on UNIX, where computer networking more or less developed. Probably all networking protocols in use on the internet are native to UNIX and/or Linux, so one can expect that UNIX and Linux would network better than any other platforms. Setting up a network on a Linux machine is surprisingly simple, because Linux handles most of the work; you just have to give it the correct addresses. Linux is made for networking. A large part of the Web is running on Linux boxes, especially because of the Apache Web Server which dramatically defeated its commercial competitors, proving the effectiveness and viability of the Open Source approach. 

 

Sun Microsystems’ Solaris

 

Sun Microsystems created the Solaris version of Unix. Solaris is multiplatform; it can run on a system with an Intel CPU as well as on a SPARC station.  The processing can be either 32-bit or 64-bit.  The 64-bit processing capacity improves performance by up to 10 times.  The Solaris operating system is fully integrated with TCP/IP and other open standards, ensuring interoperability on a heterogeneous internetwork.  Solaris adheres to the POSIX, Unix 98, and X/Open standards for application portability.  Solaris also adheres to Internet Engineering Task Force (IETF) and WWW Consortium standards for Internet services interoperability.  Solaris is extensible using device drivers, STREAMS, and file systems. Device drivers enable the Solaris kernel to access I/O devices, such as network interface cards, CD-ROMS, and tape drives. Solaris drivers can be installed and removed on a station without rebooting. STREAMS is an application programming interface (API) that can be used by new service modules to provide greater functionality File systems are used by Solaris to configure the disk volumes and file compatibility. When a new file system is installed, Solaris has a new way to configure disks and their files.  In short, all network operating systems have a lot in common.They have a way to share files, share printers, manage the network, and interoperate with various protocols Table 2.7 shows the summary of major network operating systems.

 

Summary of major network operating systems.

 

Windows NT 4.x supports TCP/IP, IPX, DLC and it’s features are: Domain structure, file and printer sharing, NetBEUI, Windows 95 GUI, SMP capable, software RAID, RAS, greater Internet awareness, Services for Macintosh, runs SMB over TCP/IP.

Windows 2000 supports TCP/IP, NetBEUI, IPX, DLC and it’s features are: Active Directory Service, file and printer sharing, Windows 95 GUI, SMP capable, software RAID, RAS, Internet aware and browser integration, Services for Macintosh, supports TCP/IP natively.

NetWare 3.lx supports TCP/IP, IPX, AppleTalk and it’s features are: Bindery structure, file and printer sharing, Novell’s text interface, supports mirroring and duplexing, uses NLMs to add other software features, highly intelligent login script features, DOS-based tools, supports multiple clients, including OS/2, Macintosh OS, Unix, and Windows. TCP/IP is added protocol, not native support.

NetWare 4.x supports TCP/IP, IPX, AppleTalk and it’s features are: Novell Directory Services, file and printer sharing, Novell’s text interface, supports mirroring and duplexing, uses NLMs to add other software features, login script features with enhanced capabilities for NDS structure, DOS-based and Windows-base tools, supports multiple clients, including OS/2, Apple, Unix, and Windows. TCP/IP is added protocol, not native support.

NetWare 5.x supports TCP/IP, IPX, AppleTalk and it’s features are: Novell Directory Services, file and printer sharing, Java graphical interface, supports mirroring and duplexing, uses NLMs to add other software features, hierarchical login scripts with enhanced NDS features, tools are mainly Windows based, supports multiple clients, including OS/2, Apple, Unix, and Windows.  Has remote connectivity and Internet Web services built in, supports TCP/IP natively.

Unix supports TCP/IP and it’s features are: Network Information Services, file and printer sharing, full Internet applications and utilities, supports RAID, uses daemons to add services, has a cumbersome command-line interface, best clients are other Unix machines but supports DOS, Windows, and OS/2.

 

Although Windows NT/2000, NetWare, and Unix are widely used, there are, and have been, other network operating systems. Some enterprise internetworks are built almost entirely on some of these network operating systems. Others have a single server located here or there. Either way, it is not unlikely for a network technician to run into one of these NOS’s