UNIX/Linux Networking

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 partbecause 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.

Here, you will learn about these UNIX/Linux topics:

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

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. 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.

Client Support and Interoperability

UNIX servers use primarily Internet standard protocols, like TCP/IP, FTP, HTTP, LPR, and soon. 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.

Authentication

UNIX can use multiple methods of authentication. It depends on whether the OS is UNIX or Linux and what kind of software is running for authentication, although remember that UNIX generally uses Internet standard protocols. So, UNIX can use Lightweight Directory Access Protocol (LDAP) or Kerberos for authentication. But there are clients for NDS and AD as well. It just depends on what kind of software is running on the server or how it has been configured.For example, you can set up a Linux box with an NDS client so it can work with other NetWare servers. Or, you can set up a UNIX box with its own LDAP server.

File and Print Services

As you might expect, UNIX file and print services are TCP/IP based. Therefore, protocols like FTP, NFS, and HTTP are used with standard file sharing. UNIX printing uses the LPD/LPR combination. But there is UNIX software available that makes UNIX appear as a Windows server. This software is known as Samba. It uses the standard Server Message Block (SMB) protocol—the same protocol that Windows networking uses. Samba is freely available on the Internet.

Application Support

UNIX has plenty of application support because it is the oldest of the NOSes .However, it is important to note that applications are usually made to run on the specific version and flavor of UNIX. For example, an application written for Sun Solaris may not run on SCO UNIX, even though they are both UNIX.

Also, a large amount of UNIX software is available for free on the Internet. It can be downloaded and installed, but there may not be any technical support available for it if you get it for free.


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