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Part I: Introduction and Planning
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1: Internetworking UNIX and Windows 2: UNIX Overview 3: Windows Overview 4: Samba Overview
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1: Internetworking UNIX and Windows
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When network engineers talk about internetworking, the flow of conversation usually eddies around the various lower-level protocols and circuits involved in the connectivity between some set of networked devices, be it computers, routers, switches, or just about any pair of semi-intelligent appliances. They don't normally use the term when discussing connectivity between services residing higher up in the protocol stack (Table 1.1). Table 1.1 OSI Protocol Stack
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7 Application 6 Presentation 5 Session 4 Transport 3 Network
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User interface and services Application data transformations Connection authentication End-to-end data ordering Routing and reporting mechanisms
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2 Data 1 Physical
Packet format, integrity, and address Physical hardware specification
Anything above layer 3 or 4 is just a glob or cloud that represents the endpoints in a networked conversation. System administrators, on the other hand, tend to extend the scope of internetworking to include the union of protocols and upper-layer services that result in some meaningful unit of interoperation between the cooperating systems. An example is the set protocols and services required to share files between platform "A" and platform "B". Given that a common set of supported protocols can be found, it is generally possible to build the corresponding set of software services to facilitate resource sharing even between quite dissimilar operating systems. Enter "Samba," which represents just such a suite of software services working in concert with standard protocols like Server Message Block (SMB), Common Internet File System (CIFS), NetBIOS, and Transmission Control Protocol (TCP) to internetwork UNIX and Windowsbased resources (Figure 1.1). Thus the title for this text: Samba: UNIX and Windows Internetworking.
Figure 1.1: UNIX, Windows, and Samba
Why do we speak of UNIX and MS Windows internetworking It is not uncommon these days to find a growing mixture of UNIX and Windows-based systems coexisting, for better or worse, in most organizations. This might seem a bit odd given that these operating systems are incarnations of somewhat different development histories and philosophies (Table 1.2 and Table 1.3). One is driven from an open systems and standards perspective and the other represents a more proprietary attitude, with a focus on business and personal use requirements. This is not to say that over time each of these operating systems has not had to address all of these issues to compete in the marketplace. Each has its own strengths and weaknesses. This is likely why we are seeing a marriage of these platforms within most enterprises today. One complements the other in addressing the demands of the complex heterogeneous computing environments found in businesses, schools, and even the home. The importance of seamlessly internetworking these two worlds has gained the attention of traditional "UNIX-only" user groups like the USENIX Association. Over the last few years USENIX has held special symposia dedicated to UNIX and Windows NT
integration. The USENIX Large Installation Systems Administration (LISA) group has also held conferences on UNIX and Windows topics. In most instances attendance at these conferences has been close to overbooked. Table 1.2 UNIX Development History
1969 1970 1973
Thompson develops single-user system on DEC PDP-7 Kernighan coins the name UNIX Ritchie develops C language UNIX rewritten in C ACM publishes Thompson and Ritchie's paper on UNIX Bell Labs licenses UNIX V6 to universities SCO and Interactive Systems founded Thompson & Joy develop BSD 1.0 UNIX Version 7 BSD 2.0 Berkeley ARPAnet Contract BSD 3.0 BSD 4.0 Microsoft develops XENIX SUN founded AT&T System III SUN becomes Sun Microsystems AT&T System Vtab BSD 4.2 SUN SunOS Hewlett-Packard HP-UX GNU Project conceived AT&T System V.2 DEC ULTRIX X/Open Founded Sun NFS POSIX 1003.1 published AT&T SYSV.3, Streams, RFS BSD 4.3 IBM AIX RT
1974 1975 1977
1981 1982
Commercial X Windows release 1987 1988 AT&T SYSV.3.1 AT&T SYSV.3.2 BSD 4.3 Tahoe AT&T SYSV.4 Open Software Foundation Founded OSF Motif UNIX International Founded Internet Worm on Nov 2 BSD 4.3Reno IBM AIX RS/6000 OSF/1 Apple, IBM, Motorola Venture Sun Solaris 1.0 Linux 0.02 BSD 4.4 Novell buys UNIX System Laboratories Novell grants UNIX trademark to X/Open 386BSD 1.0 FreeBSD 1.0 NetBSD 0.8 Linux 1.0 Linux International Open Source Program
1992 1993
UNIX has been around for about 30 years. Initially found primarily in academia and research environments, it is a powerful multi-user, multitasking operating system suitable for a wide range of applications. It is easily scalable from small single-user workstations to very large mainframe, multiprocessor, and cluster computing architectures supporting thousands of simultaneous users and processes. Because of the availability of source code, built-in programming environment, and a solid focus on standard interfaces and protocols, UNIX is easily ported to most hardware platforms. This has resulted in a rich set of public and vendor implementations. Yet general access to source code has also kept UNIX somewhat vendor independent. When we use the term "UNIX" we are usually referring to the full array of public and vendor versions available in the marketplace. It is true that each rendition of UNIX tends to have its own nuances, add-on features, and variations on the basic theme, but in general functionality has remained quite consistent across platforms over its long development history. In fact, the collective expertise of this large development community has greatly contributed to the overall maturity, interoperability, and robustness of the operating system.
On the down side, the most prominent complaint concerning UNIX is directed at its character-based command-line user interface. Although the rich set of commands, interpretive shells, and scripting languages provide a great deal of functionality for the programmer and systems administrator, their use and existence are not easy for the novice user. Most commands are cryptic shorthand strings and often derive context from the shell under which they are invoked. This can be quite confusing to all but experienced users. A graphical user interface called X Windows can be added to the operating system, but it does not entirely shield the user from the intricacies of the command interface. Another criticism is that although most applications can be easily ported between the various versions of UNIX, they are generally not binary-compatible from one vendor platform to another. This has tended to limit the availability of some products across all UNIX platforms. UNIX has found a home in many businesses because of its open interfaces and tight integration with Internet technologies. UNIX and the Internet grew up together. As specifications for internetworking protocols like TCP/IP were developed, they were quickly interwoven into the networking fabric of UNIX. Most of what we have come to expect concerning basic information-sharing services over the Internet were developed under UNIX. This has enabled UNIX to be used as a protocol and server Swiss Army knife for quickly and cost effectively connecting legacy proprietary computing infrastructures to the Internet. Table 1.3 Windows Development History
IBM contracts with Microsoft for PC OS Bill Gates buys QDOS MS-DOS created from QDOS First IBM PC MS begins "Interface Manager" development Windows announced MS-DOS 2.0 Windows 1.0 Dropdown menus Mouse support Windows 2.0 Icons and overlapping windows MS & IBM begin work on OS/2 MS & IBM split on OS/2 and Windows development Windows/386 Windows 3.0 Program and File Manager Network support Windows 3.1 Object Linking and Embedding (OLE) Multimedia
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MS begins work on "New Technology" OS 1994 Windows NT 3.1 32-bit OS Protected modetab Security Windows for Workgroups 3.11 Win32s Windows 95 Pre-emptive multitasking Threads Windows NT 4.0 Windows CE IBM ends OS/2 development Windows 95 OSR2 Active Desktop FAT32 Includes Internet Explorer 3.0 Windows 98 Integrated Internet Explorer 4.0 Windows 98 SE Internet Explorer 5.0 Windows NT 5.0 renamed Windows 2000 Windows 2000 Beta3 Release Candidate1
The Microsoft Windows success story can be easily attributed to its point-and-click user interface and low-cost hardware platform. The widespread familiarity with the Windows interface, its rich set of productivity tools, and its commodity hardware component base have quickly made it the predominant world standard in single user desktop computing. This is pretty impressive feat considering it is little more than half the age of UNIX. Microsoft has done a very good job of embracing networking technologies, incorporating standards, and enhancing the user interface to extend productivity from the desktop to the workgroup and most recently the Internet. This began with peer-to-peer networking in Windows for Workgroups. Next came interoperability with Novell-based networks, client/server networking with Windows NT and UNIX, and strong Internet connectivity with tools such as Internet Explorer. On the server side, the Microsoft story is still relatively new. Windows NT (New Technology) is only a little over five years old, yet in this short time it has captured a significant portion of the database client/server market. Windows NT incorporated bits and pieces of UNIX, VMS, OS/2, Netware, and existing Windows architectures to provide a multitasking networking service designed for tighter integration of and administer workgroup LANs under a new structure called domains. NT version 4.0 provided Windows-based networks closer ties with the Internet by including common Internet services like DNS, FTP, web, and SMTP-based electronic mail. Windows 2000 will extend this functionality by including additional internetworking tools like LDAP directory services, Kerberos authentication, and public-key services, each of which is closely linked to existing Windows networking and security services.
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Although touted as the UNIX-killer, Windows NT has yet to fully replace UNIX services in the back room. Likewise UNIX does not provide the tight desktop support services and friendly user and administration interfaces that have been the hallmark of Windows. The result is that both operating systems are common fixtures in most shops. The challenge, then, for the system administrator is how best to simplify the administrative and management tasks of maintaining both operating systems, and how to facilitate seamless user access to the resources that reside in each world. This is where services like Samba become essential tools to smoothing the rough edges of UNIX's and Windows' coexistence.
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