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UNIX and NT Networking |
I was not able to find good concise and impartial tutorials on UNIX and NT Networking, so I wrote the summaries below. We will explain, elaborate, and discuss these topics in class also.
UNIX is a multi-user, multi-tasking, hardware-independent operating system originally developed at Bell Laboratories around 1970. There have been and are several variants of UNIX, including BSD (Berkeley Software Distribution), AT&T System V, and the increasingly popular Linux (available free and well suited to microcomputers). Most of the operating system is written in C, a programming language which was developed after B!
UNIX includes a number of basic networking utilities, including a group of tools called the UUCP system (UUCP stands for UNIX-to-UNIX Copy, which is actually just one part of the tool set that bears its name). UUCP relies on point-to-point interconnections of host machines, and is generally most suitable for low speed connections in homogeneous UNIX environments. For many years, UUCP was the primary distribution vehicle for USENET news, however that has now largely shifted to TCP/IP methods.
TCP/IP protocol implementations (TCP, UDP, IP . . .) and applications (Telnet, FTP . . .) come with most UNIX variants ever since they were first included in BSD distributions. Many TCP/IP tools such as Ping, netstat, and ifconfig began on UNIX. A number of "remote commands" are available, such as rlogin (remote login), rsh (remote shell), and rcp (remote copy). Many choices in client software for networking-related applications such as email are also available. A common approach to hosting Internet services such as Web servers is to run the Web server software in the background as a "daemon."
The rough equivalent to the virtual disk drives of a PC LAN is the Network File System, or NFS, and the related Remote File Sharing (RFS) and Distributed File System (DFS). These provide a networked distributed file system allowing users to access files across the network relatively seamlessly. Security was a secondary concern during early development of UNIX, and while great improvements have been made there are a number of well-known weaknesses that a good UNIX system administrator should be aware of and avoid.
UNIX has carved out and retains a niche as a powerful applications server platform in networked environments. On a private LAN, this might include acting as an SQL database server. On the Internet, UNIX is the predominant platform for very high-volume servers such as HTTP (Web) and FTP (file transfer). Until recently, UNIX was virtually the only platform which could host critical Internet services such as DNS (Domain Name Service).
Users typically interact with a shell, such as the System V shell, C shell or Korn shell, or with a windowing system such as X Windows. High-level programming can be done with shell scripts and related programming languages such as Perl (the latter popular for server-side Web processing using the Common Gateway Interface or CGI). There are a variety of utilities for text editing and processing, file manipulation and management, etc.
The X Window system is a very powerful client-server user interface which separates the client application processing from the server display functions and allows them to communicate over a network. Note that an X client is the application program (often running on a powerful host) while an X server is a display program (often running on a workstation)--thus the definition of client and server are sometimes perceived as opposite to those in other client-server environments. Several customizable graphical user interfaces such as Open Look and Motif add to the basic functionality of X. To help grasp the power of X, consider that a program running in this environment can take user input from a second machine's keyboard, input from a file on a third machine, and display the results on a fourth and fifth machine, with each machine using different hardware and even operating systems. Can you do this with Microsoft Windows?
A networking environment using Microsoft Windows NT Server provides much the same basic functionality as one using Novell NetWare. This includes file sharing through virtual drives and a Universal Naming Convention, print sharing and queuing, logon scripts, application sharing, etc. Multiple client support is provided, largely limited to DOS/Windows and Mac clients.
Some notable features of NT Server are:
NT Server shares a great deal of code with NT workstation. Both have moved away from many limitations of previous Windows versions: they offer multitasking (but are not multi-user per se) and a 32-bit flat memory model. Somewhat similar to UNIX, NT has a core "kernel" operating system component and various abstraction mechanisms to modularize other functions. The file system has been improved, with NTFS (NT File System) providing better performance and security.
NT Server supports three main network protocol suites: NetBIOS/NetBEUI, TCP/IP, and IPX/SPX. NetBIOS (Network Basic Input/Output System) and NetBEUI (NetBIOS Extended User Interface) provide support for legacy LAN applications and a number of Microsoft-specific functions such virtual drive mapping. TCP/IP and/or IPX/SPX can be used for network and transport layer functions for compatibility with Internet and Novell NetWare environments, respectively. A number of TCP/IP applications such as a Telnet client and FTP client/server are now included.
Administrative tools for NT Server include the User Manager for creating and managing accounts, the Server Manager for stopping and starting services (the rough equivalent of UNIX daemons), etc., the Disk Manager for setting up partitions and RAID management, the Performance Monitor for monitoring usage of the CPU, memory, etc., the Event Viewer which logs important system and security-related events, and the Network Monitor Tool, which operates as a software protocol analyzer.
The security of several NT Servers can be managed by setting up one of them as a domain controller and the rest as members of that domain. Users can then log into the domain rather than each individual server, yet access resources from all servers. Domain can then establish trust relationships between each other for wider access to resources. This approaches enterprise-wide network management but is not a completely integrated and consistent solution.
NT Server 4.0 has moved to a Windows 95-like Explorer interface, which gives a network manager a very similar interface to that used on user workstations (but with additional folders, etc. for network management functions).
Tools such as Gateway Service for NetWare allow NT Server clients to access resources on NetWare servers without running IPX, and the Migration Tool for NetWare encourages the transfer of files and administrative information from NetWare servers to NT servers.
Expected in 1998, Windows NT Server 5.0 will include a number of significant changes. These include built-in multiprotocol routing (with RRAS--Routing and Remote Access Service), enterprise-wide Active Directory Services, server clustering and fail-over (preventing interruption of service if one server fails), increased importance of DNS, possible disappearance of WINS, and many other changes. As one network magazine editorial explains, if you are an expert in NT Server now, you won't be when 5.0 comes out!
Note: Some other terms that are important to this chapter were introduced and/or listed with prior chapters.
Last modified on November 10, 1997 04:51 PM by Robert Minch (risminch@cobfac.idbsu.edu).