Client Support and Interoperability "UNIX/Linux"

Client Support and Interoperability
UNIX servers use primarily Internet standard protocols, like TCP/IP, FTP, HTTP, LPR, and so on. Therefore, just about any client that can be configured with TCP/IP and a web browser is
a potential client. Most other NOS platforms are moving to this idea of using TCP/IP and Internet standard protocols for all communications and network services, but it’s been difficult
because each vendor has a lot invested in its own proprietary systems.

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Features "UNIX/Linux"

Features
UNIX flavors incorporate a kernel, which constitutes the core of the operating system. The kernel can access hardware and communicate with various types of user interfaces. The two most popular user interfaces are the command-line interface (called a shell) and the graphical interface (X Window System). The UNIX kernel is similar to the core operating system components of Windows Server and NetWare. In UNIX, the kernel is typically simple and, therefore, powerful. Additionally, the kernel can be recompiled to include support for more devices. As a matter of fact,
some flavors (like Linux) include the source code so that you can create your own flavor of UNIX. 
      The UNIX flavor that has been receiving the most attention lately is Linux. Linux is a fairly easy-to-use (as UNIX goes, anyway) flavor developed by Linus Torvalds at the University of
Helsinki, Finland. He started his work in 1991 and released version 1 of the Linux kernel in 1994. As this book is being written, the current Linux kernel is version 2.2. Since Linux development
teams add features daily, it’s only a matter of time before a new release.
      Linux runs mainly on the Intel platform, although some distributions run on Rapid Instruction Set Computing (RISC) processors such as the MIPS and Alpha. Attempts have been made,
successfully, to run the RISC version on other platforms, such as the Macintosh. Linux is easy to install, and most distributions are free and include the source code. Hardware requirements
can vary widely with each distribution.
     And there are various flavors of Linux. People acquire Linux, come up with a new feature, recompile Linux with the new feature, and then redistribute it. According to Linux’s distribution
agreement (called the GNU public license), any sale or distribution must include the source code so that others can also develop custom Linux applications.
      Most Linux distributions include a full suite of applications, such as a word processor, the X Window System graphical interface, and source code compilers. Additionally, most UNIX applications that comply with the POSIX standard should run on Linux with little or no modification.

Because Linux is a flavor of UNIX, it comes with network support for TCP/IP. In particular, Caldera’s OpenLinux is making its mark in the networking world. OpenLinux was developed for corporate
networking, so it supports multiple protocols (including Point-to-Point Protocol [PPP], Apple- Talk, IPX, and SMB). It also includes support for integration with other network operating systems.
    Two other distributions of Linux should be noted: Red Hat and Slackware. Red Hat Linux is the most portable version of Linux, with code that runs natively on the Intel, Alpha, and SPARC
processors. The Slackware distribution was specifically designed for the Intel platform and, as such, supports many PC hardware devices, including Ethernet and multiple (up to 16) processors.

NOTE:

For more detailed information on Linux, as well as locations to download it, check out www.linux.org. For a list of the various English Linux distributions,check out www.linux.org/dist/english.html.

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UNIX/Linux

UNIX/Linux
Of the other network operating systems available, the various forms of UNIX are probably the most popular. It is definitely the oldest of the network operating systems. Bell Labs developed
UNIX, in part, in 1969. We say “in part” because there are now so many iterations, commonly called flavors, of UNIX that it is almost a completely different operating system.
     Although the basic architecture of all flavors is the same (32-bit kernel, command-line based, capable of having a graphical interface, as in X Window System), the subtle details of each make
one flavor better in a particular situation than another.
In the following sections, you will learn about these UNIX/Linux topics:

• Features
• Client support and interoperability
• Authentication
• File and print services
• Security

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Security "Novell NetWare "

Security
NetWare is arguably the most secure NOS. It uses public key encryption during the login process (passwords are never sent in cleartext between client and server). Plus, you cannot get
access to the local files unless you are logged in with a proper client. NetWare is the only NOS that has been certified by the National Security Agency (NSA) as C2 Red Book secure, which
means that it is secure enough for U.S. government use.

     In addition, NetWare uses NDS for the back-end authentication. Clients will send authentication requests to NDS and NDS will look up the user in the Directory and verify that the attempted login is an appropriate request and that the user information is valid.

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Application Support "Novell NetWare "

Application Support
Application support is one major downfall for NetWare. NetWare is a server-only platform. Novell’s view is that a server should run only services, not desktop-type applications. To that
end, NetWare servers run services very well. But NetWare does not run desktop applications (like word processing programs, spreadsheets, or what have you) at all.

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File and Print Services "Novell NetWare "

File and Print Services
NetWare is known for its file and print services, that is, the network services that serve out files to client computers and allow printers to be shared over the network. NetWare was the first NOS to provide file and print services for PCs and it arguably is the best at it. As a matter of fact, the file services are so advanced that NetWare can be made to appear as any kind of file server. For example, a NetWare server can be made to look like an AppleShare server to Macintosh clients, an NFS server to UNIX clients, and so on.

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Directory Structure "Novell NetWare"

Directory Structure
Directories like Novell’s that use the X.500 standard are hierarchical in nature and use a structure called the Directory Information Tree (DIT). In a DIT, the top level of the structure is called the [Root], which leads to the fact that the DIT is commonly referred to as an inverted tree. Making up the structure below the [Root] are intermediate objects and leaf objects.

NOTE:

Leaf objects are also called terminating objects because they are at the “ends” of the tree.

To easily find objects in the Directory, it must be further organized through the use of intermediate objects. They can be likened to alphabetized subsections of a telephone book (A, B, C, and so on).
Leaf objects represent resources in your organization (such as people, devices, applications, services, and so on) and can be likened to each name in a telephone book (Smith, Chang,
Moreau, and so on).

     Each object in the tree has attributes, which are properties that define the object. Information stored in an attribute is called a value. An example of an attribute in a telephone book is phone
number, and the value is the number itself. Objects can have many different attributes.
     Each object (depending on its type) can be located only in certain places within the DIT.
Labels are used to identify object types and thus their possible locations in the tree. Each label is a one- or two-character abbreviation of the object type or of an object attribute. Each object is also graphically represented in the tree. A Leaf Object’s graphical representation varies depending on the type of Leaf Object (for example, user, printer, and application).
Object types, where in the tree an object is allowed to reside, and object attributes follow rules called the schema.
      Table 5.3 describes each of the possible object labels in an NDS tree, the associated object type, and the possible location of the object in the tree.

TABLE 5 . 3 Labels, Object Types, and Object Locations in the Tree

When accessing a particular object, you must understand the idea of context. An object’s context is its exact location within the tree, taking into account all of the containers that it is in. For example, if a user, Connie, was in the sales organizational unit, which in turn was in the Acme organization, the user object Connie would have the context of

OU=SALES.O=ACME

Because it has the OU= and O= labels, this name is known as a typefull context. This type of name is used when there must be no doubt about the type of container that exists at a particular level.

In addition, Connie’s typefull distinguished name (the name of an object plus its context) would be

.CN=CONNIE.OU=SALES.O=ACME.

NOTE:

Contexts and names can also be used without their container labels, like so: SALES.ACME (for a context) .CONNIE.SALES.ACME (for an object’s distinguished name)

This is known as a typeless context and is used most often because it’s easier to remember.

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