Despite what many people claim, Windows NT simply can't replace UNIX in every situation. In addition, the cost of migrating from UNIX to NT is prohibitive and, in many cases, NT doesn't provide UNIX administrators with the necessary applications. Regardless of the reason, necessity has made integrating NT and UNIX—rather than replacing one with the other—the rule.
Since Microsoft introduced Windows, the company has fallen short in the number and functionality of Windows command-line tools—NT's interface is primarily graphics based. Although alternative sources (e.g., UNIX) have offered these tools for years, no integrated product exists.
The introduction of Microsoft Windows NT Services for UNIX (SFU) fills this hole. However, the name is misleading. SFU doesn't provide NT services on a UNIX machine. Instead, it provides what many people consider to be UNIX services on an NT machine. Understanding this distinction is vital to understanding what services SFU offers and to whom. SFU simplifies resource access, facilitates password synchronization, and eases administration in mixed NT and UNIX environments.
NFS
NFS, which Sun Microsystems originally developed, is one of the first protocols that lets you mount remote file systems and make them appear as if they were local. This functionality lets you have one set of resources available from several machines. NFS has been a staple of all UNIX dialects for many years and is available for NT, Windows 9x, Windows 3.x, and other OSs.
Server and client components. Like the Common Internet File System (CIFS) that Windows uses, NFS consists of a server and a client component. On UNIX, NFS is usually available as one package, so you need to explicitly configure a UNIX machine as a server or a client. However, vendors of Windows NFS products usually package the products as either clients or servers. Only a few vendors bundle the client and server product into one package.
Rather than create an NFS product from scratch, Microsoft integrated into SFU two existing NFS products from Intergraph: DiskShare, which is the NFS server, and DiskAccess, which is the NFS client. Microsoft provides SFU only for NT, but Intergraph offers its two products for NT and Win9x. Microsoft provides both server and client NFS products in SFU, so you can implement NFS in almost any environment.
Although both client and server versions are available, you don't need to install both versions. Deciding which components to install depends on which machines are providing resources and to whom. For example, if you have several UNIX machines that need to access files on one NT machine, installing the NFS server version on the NT machine makes the most sense. However, if several NT machines need to access files on several UNIX machines, installing NFS clients on the NT machines is more practical. By providing the server and client products, Microsoft lets administrators deploy SFU components as needed. Thus, administrators can configure SFU components on fewer machines, thereby decreasing the software cost and reducing the time necessary to administer SFU systems.
The NFS client is completely transparent to users. To access resources on an NFS server, clients use the same tools they use to access CIFS resources, such as Windows Explorer, Network Neighborhood, and File Manager.
Regardless of whether the SFU system acts as a server or a client, the system must convert the user information between NT and UNIX. UNIX tracks users by their user ID and one group ID (GID). NT user IDs have a different format from UNIX users' user IDs, and NT lets a user exist in multiple groups.
Authentication. NT's and UNIX's authentication methods are different, so SFU's NFS provides two authentication methods: pcnfsd and the Network Information Service (NIS). Pcnfsd lets users enter a username and password to gain access to an individual machine's resources. NIS provides a centralized mechanism for sharing user and password information across multiple machines, similar to the way machines share information within an NT domain. However, NIS provides a much finer level of control.
SFU's NFS server component acts as the intermediary between a UNIX client and NT file services, so the NFS server can access any file system type that both the UNIX and NT systems can access, such as FAT, High-Performance File System (HPFS), CD-ROM File System (CDFS), and NTFS. The NFS server performs translations on NT machines, so clients aren't aware of what file system their system is accessing. In addition, the NFS server performs the conversion between UNIX and NTFS permissions. UNIX usually offers only read, write, and execute permissions to the owner, group, and any other users. NT uses ACLs to handle permissions. The SFU NFS server must convert back and forth between NT and UNIX permissions. The NFS server maps the UNIX permissions to the NT Security Descriptor, based on rules that depend on which direction the NFS server is converting.
Licensing. An important distinction between the client and server versions is their licensing policies. The client version is valid only for the machine on which you install SFU, which means you have unlimited access to UNIX machines. SFU's server component licensing permits an unlimited number of clients access to the NFS server as long as each client has an NT Server Client Access License (CAL) for that server.
In addition, SFU licensing depends on the system you install SFU on. For example, the NT Workstation license limits you to 10 client connections, so the same applies to the NFS server component. However, NT Server limits you to the number of CALs you have. Table 1 outlines Microsoft's licensing policy for SFU components.
Gateway services. SFU 2.0 includes an NFS gateway that you install on a Windows 2000 (Win2K) or NT server. This gateway mounts NFS resources from UNIX machines. The resources appear as standard Windows shares. You can share these resources with other Windows machines, including NT Workstation and Win9x systems, without installing the SFU NFS client component on each machine.
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