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What is Linux? What is BSD? Why use BSD and/or Linux?

Linux and BSD are full-featured, complete operating systems. They are alternatives to mainstream operating systems like Microsoft Windows 98 or Apple Macintosh OS 9.1. A huge variety of software is available for Linux and BSD.

What is Linux?

Linux is a freely-available operating system. Really, Linux is a freely-available kernel -- the core, nucleus or center of a complete operating system. (Basically, a kernel schedules and supervises how the computer's resources are used.) Linux-based operating systems contain a variety of free software, including a lot from the GNU project. Because of this, Linux operating systems are often called "GNU/Linux".

A variety of Linux operating systems are available for free and commercially for sale. Some popular Linux operating systems include Debian GNU/Linux, Slackware, Red Hat Linux, Mandrake Linux, and SuSE Linux. Some Linux operating systems fit on a single floppy disk, others include gigabytes of information and applications. Although there are differences in the Linux operating systems, most use the exact same standard utilities and software.

These complete operating systems include graphical windowing interfaces, desktop office applications for word processing and spreadsheets, a variety of games, text and documentation processing tools, networking utilities and internet applications. Thousands of programs for accomplishing almost all known computer tasks are available for Linux.

Linux operating systems can usually replace most proprietary or mainstream operating systems, although some file formats differ. In addition, under most circumstances, the programs from one operating system will not run under another operating system. Freely-available applications and utilities are available to run and use Windows applications and Microsoft documents under Linux.

What is BSD?

BSD operating systems are very similar to Linux operating systems. In fact, most programs developed for Linux systems run on BSD systems. (And most programs developed for BSD systems work with Linux.) BSD and Linux systems can be configured to appear and act the same for end-users. And since most of the software is the same, administration is very similar and, in some cases, identical.

BSD has an older history (started in the late 1970's) than Linux, and it also uses a variety of the same applications and utilities. Linux is actually just a kernel which needs other utilities to truly function as an operating system. But the BSD operating systems include a kernel and numerous BSD-licensed utilities and applications.

BSD stands for Berkeley Software Distributions and BSD licensed code is freely-distributable with copyright and liability disclaimer. Due to its minimal license, BSD software is freely modified and is used in proprietary or commercial software.

The BSDs include FreeBSD, OpenBSD, NetBSD, and BSDi's commercial BSD/OS. Apple's free Darwin operating system and commercial Mac OS X are also based on BSD.

Why use BSD and/or Linux?

Linux and BSD are proven and mature products. BSD software has been in constant improvement and development for over twenty years; it powers the world's busiest (and most popular) FTP servers and websites. For almost ten years, Linux has been under constant development by a worldwide network of expert software developers. It is the operating system of choice for over 30-percent of the server market. BSD and Linux can be used for a variety of reasons:

GIMP, AbiWord, Navigator, gnumeric under blackbox on NetBSD

Save Money

The standard BSD and Linux operating systems are freely-available. They are not shareware and they do not have any hidden costs. The software licenses for the majority of all BSD and Linux software state that the software is freely redistributable.

BSD- and Linux-based operating systems and related software can be used to replace expensive and proprietary routers and firewalls, and replace a variety of commercial office software.

The free Linux and BSD operating systems do not have any per license fees. A small office can easily save hundreds of dollars by using BSD and/or Linux operating systems instead of mainstream and proprietary operating systems. Large schools and businesses can easily save hundreds of thousands to millions of dollars by using BSD and/or Linux.

And often older hardware can be recycled (reused).

Based on proven ideas

BSD and Linux are primarily based on Unix ideas -- some with over thirty years of real use, history and experience. They are multiuser and multitasking. Different users and different applications can be assigned access permissions (or restrictions). One user can't be allowed to disrupt other users' work. Unix (and BSD and Linux) is used to support thousands of simultaneous users. It is designed to securely separate users and programs; if one program crashes it can't be allowed to take down the entire system. These ideas help make BSD and Linux very stable.

Efficient, Fast, Stable

The graphical, windowing interfaces available are not intertwined or built into the kernel or base operating systems. In fact, the graphical, windowing interface is not even needed or used for most server tasks. As you can imagine, separating the graphics from the core system dramatically improves system speed, efficiency and stability.

Although a variety of BSD and Linux-related software is designed to accomplish numerous tasks, most of the software is built to be minimal and to accomplish distinct tasks. This also increases performance and efficiency. BSD and Linux servers are highly optimized.

BSD and Linux systems frequently run for well over one hundred days, over a year, and many run for several years. These operating systems and related software are extremely stable.

Office / Desktop Applications

A variety of easy-to-use, powerful, and high-quality office and desktop applications are available (for free). Some popular applications include AbiWord, LyX, OpenWriter, KPresenter, gnumeric (spreadsheet), Kivio (flowcharting), The GIMP (image editing), and GnuCash (personal finances). The popular office suites include StarOffice, OpenOffice, KOffice and GNOME office.

Most of the office suites are interchangeable and can be used with each other. In addition, they can usually import (and sometimes export) most common and standard Microsoft Office formats.

Internet access, browsing and email

BSD and Linux is full-featured for Internet access. They come with full functionality for regular dial-up, PPP-based, cable modem, DSL, ethernet access and other connections. Web browsers include Galeon, Konqueror, Netscape Navigator, Opera and Mozilla. (In addition, text-based web browsers are also available.) Email clients include Netscape Messenger, KMail, Balsa, Evolution (includes calendaring and personal information manager) and the popular text-based email clients, Pine and Mutt.

File, printer and network servers

BSD and Linux are developed on and for the internet -- and their real strengths are for running network services. Most internet servers run BSD and Linux-related software; in fact, top sites like Yahoo! and HotMail are powered by BSD.

BSD and Linux can be used for database servers. MySQL and PostgreSQL are two full-featured and popular database servers. In addition, several commercial databases (such as Oracle) are available.

They can be used for printer servers using the LPR protocol (which is also available for other operating systems), CUPS and other printing queue servers. In addition, a variety of postscript and other printer filters (drivers) are available. BSD and Linux can also be print servers for regular Windows environments using Samba.

Samba is used to share SMB/CIFS files and services. In fact, a Samba server can be a Windows NT domain controller. NFS can also be used to share files. BSD and Linux can be networked or share files (and services) with a variety of different operating systems, architectures and hardware.

BSD and Linux systems can easily be used to implement mail services. A variety of mail servers are available; and several web-based email applications are available. Email can be filtered for spam and virus.

Serving webpages and other documents is simple with Apache, ftpd and several other HTTP and FTP servers. Apache is the most popular webserver in the world, powering around 70-percent of all websites.

In addition, BSD and Linux are commonly used to power time, RADIUS, dial-up and a variety of other services.

BSD and Linux are great for consolidating different platforms; this interoperability can help save money and time.

Firewalls, security and routers

A lot of network security innovations are developed on BSD and Linux systems. BSD and Linux can be easily used as a router, proxy-based firewall, and packet-filtering firewall. In addition, network address translation (NAT) can be used to masquerade external (world) IP addresses to internal (private) IP addresses for further security.

BSD and Linux can also be used to implement VPN (virtual private networks) using IPsec (IP security protocol) and PPTP (Point to Point Tunneling Protocol (PPTP), for example.

Also, the operating systems can be used for anti-spam relay rules and virus scanning. Due to the Unix-like security nature, Linux and BSD virii are rare.

BSD and Linux are also very secure, because the source code for the software is freely available -- and it has a lot of peer review. When problems are found, they are reported, quickly fixed and the fixes distributed.

As explained above, BSD and Linux are based on Unix; user's documents and programs can be separate, unusable and secure from other users.

The above is only a short description of why BSD and Linux are great alternatives to mainstream operating systems. As you can see, BSD and Linux are useful in the home, small office, and for the large organization. (If you have any questions, be sure to ask.)

Puget Sound Technology uses BSD and Linux for all of its computer needs. For example, our main internet connection goes through a Linux-based router and firewall; the webpages and graphics were created with vi and The GIMP on a NetBSD workstation; the webpages and email are served on a variety of BSD and Linux machines running Apache and Exim.

For more information about open source software, please read the "What is open source? Why use open source software?" article.

Puget Sound Technology provides professional planning and designing, implementation, operations, maintenance and training services for BSD and Linux systems, routers and networks.

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