Network Operating Systems
Network Operating Systems.
Selecting a network operating system is a very complex task. Every
NOS - Network Operating System has its
relative strengths and weaknesses. The three major types of
platforms we will survey are in the following list.
Windows Based Networks Windows platform server based networks are developed around the concept of a domain. A domain is a grouping of computers, devices and users that has a distinct boundary related to administrative authority. The words domain controller refer to the login authentication servers that hold a copy of the security accounts database. Windows NT. Windows NT has had a large variety of versions. The most recent is NT 4.0. Its user interface is actually fairly similar to that used in Windows 95, which also hints at its age. Each NT network requires a primary domain controller. This is the main server that contains the SAM - security accounts management database. A primary domain controller can also have backup domain controllers, each of which contains a read only copy of the SAM. The User Manager for Domains is the software tool that is used on the domain controller to create, manage and remove domain user accounts. This tool allows the sys admin to things such as the following.
Windows 2000. Somewhat differently, Windows 2000 networks make use of something called Active Directory to store security information. This database is hierarchical in nature as opposed to the flat file SAM. Windows 2000 domains can be joined in domain trees, which are groups of domains that share a contiguous namespace. Multiple trees can be joined into forests. This approach makes the network structure scalable to about any size. Windows 2000 does not have primary and/or backup domain controllers like NT. All domain controllers have copies of the Active Directory partition. Thus changes can be made on any domain controller. The changes are then replicated to all the other domain controllers. In order to administer accounts in Windows 2000 the sys admin works with the MMC - Microsoft Management Console. The MMC relies on snap in modules that contain the tools for specific administrative functions. Users and groups are created and managed with the Active Directory Users and Computers MMC snap in. The MMC also allows the sys admin to place objects such as users and resources into container objects called OUs - Organizational Units. Authority for any OU can be delegated. In order to map network drives in these Microsoft products you can use either of the following approaches. There are other variants, such as using Internet Explorer, but these are the two essentially different approaches.
To map a network drive in Windows Explorer you need to navigate to the folder on the remote system in Windows Explorer using the following steps.
Then the desired mapped drive shows up in the left pane of Windows Explorer. To map a network drive using the net use command via the UNC - Universal Naming Convention path. You can identify the drive using the following sort of syntax. To map a network drive to the shared resource use the following command at the command prompt. net use <driveletter: \\computername\sharename Using a command line is preferable to some users. Sharing something like printer resources is something else that frequently happens. This can happen for both local and network printers. For local printers you only need to do the following.
For network printers it would be the same if the resource has already been added. But if it hasn't then you can do either of the following.
Making use of the Add Printer Wizard is likely to be the easiest. To do this you must work through the following steps.
You can also make use of the net use command to capture the appropriate printer port. This will be much like mapping a network drive using this command. net use LPT1: \\computername\printername The computername is the name of the print server. NetWare Networks. NetWare has more than one version and each is different. There are still a number of systems running NetWare 3.x. Though most are running more recent versions of NetWare 5.x. One concept that is common to NetWare products is called a bindery. While this has different specifics in different versions it is ultimately nothing more than a database used for account management analogous to Microsoft's SAM. NetWare 3.x makes use of a bindery on each server. Each bindery stores the security information for only that server. In order for a user to access a particular server on the network they must have an account on that server in its bindery. There is no replication of such information across the network which makes network administration extremely difficult. NetWare 4.x introduced a more sophisticated directory service called NDS - Novell Directory Services. NDS resolves the issues caused by individual binderies on each server. NDS is a distributed database that allows users to have only one account on the network and access all their authorized resources. While the bindery is a flat file, NDS is hierarchical and arranged like a tree. In fact, Novell calls its network resources leaf objects. NDS was released prior to Microsoft's Active Directory, though the two have a lot in common. One can use NDS to develop OUs - Organizational Units and to find resources without knowing where the resources are physically located. Both Active Directory and NDS are LDAP - Lightweight Directory Access Protocol compatible. When NetWare 3.x is installed the administrator automatically gets two accounts. One for Guest and one for Supervisor. The Guest account has limited access. The Supervisor is the main administrative account. NetWare 4.x and 5.x have only one default account called Admin. NetWare 4.x accounts are administered with two tools.
NetWare 5.x provides a Java based administrative console called ConsoleOne. This console allows for remote network administration. NetWare 5 can also be administered through a command line or menu based utility called the Monitor. NetWare 5.1 introduced a web based tool called the NetWare Management Portal that allows NetWare 5.1 servers to be administered from a client machine through a web browser. Novell has client software to complement its server and network software. Mapping network drives on NetWare networks can be done using Windows Explorer using the same process as that used for Microsoft networks. It can also be done using the map command. map driveletter:=server\volume:directory\subdirectory The Novell client software also has this sort of capability. In order to share printers you can capture to redirect printer jobs. capture L=<portnumber> Q=<queuename> P=<printername> UNIX Networks. The UNIX operating system was first developed at Bell Labs in 1969. Because the source code is open, written in C and available free of charge to anyone who wants to modify it many versions have been developed. UNIX operating systems are run on high end workstations and servers such as Silicon Graphics and Sun machines. UNIX is often run via command line, but it can also be run through a GUI called X Windows. The administrative account is called root. Bin and sys are accounts that own and run programs. Server services are called daemons. For example, there is a print daemon and an FTP daemon. There are hundreds of different versions and releases of UNIX. Some of the most popular are in the following list.
NIS - Network Information Systems developed by Sun Microsystems can be used to manage UNIX servers. NIS allows a user to login just once to the network to access network resources. The adduser command can be used by the root account user or supervisor to create new user accounts. username: /# adduser These accounts can be modified by editing the /etc/passwd file. Some UNIX releases provide scripts to help this process. Having a GUI can also be worthwhile. UNIX also provides for groups to manage accounts. This is done through the addgroup command and the /etc/groups file. UNIX client/server interactions are usually based on the NFS - Network File System. NFS requires TCP/IP or some other NFS client software for file transfer. Mapping drives in UNIX is done through the mount command such a the following. mount servername: /directory/subdirectory /localdirectory The localdirectory that points to the remote share is called the directory mount point. This mount point must pre-exist an effort to map a share to it. Sharing printers requires making use of the lpr command. lpr -P printename filename If you enter the command without the printername then it goes to the default printer. Other commands for printer management exist such as the following.
Linux Networks. Linux is often called UNIX Lite. It was designed to run on Intel compatible computers. It also has open source code helping it to have evolved into several varieties. Linux was first developed by Linus Torvalds in the early 1990s. It can be used in a command line mode or via X Windows. It also has other GUIs such as Gnome and KDE. Most Linux and UNIX terminology is interchangeable. The administrative account is called root. Bin and sys are accounts that own and run programs. Server services are called daemons. For example, there is a print daemon and an FTP daemon. There are many different versions and releases of Linux. Some of the most popular are in the following list.
The adduser command can be used by the root account user or supervisor to create new user accounts. username: /# adduser These accounts can be modified by editing the /etc/passwd file. Some Linux releases provide scripts to help this process. Having a GUI can also be worthwhile. Linux also provides for groups to manage accounts. This is done through the addgroup command and the /etc/groups file. Other NOSs. The vast majority of networks are based on the NOSs we just surveyed. The following list gives an even briefer survey of some other alternatives.
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