RED HAT ENTERPRISE LINUX

Introduction to
Open Source & Linux

Foundations of Enterprise Linux Computing

CIS126RH | RHEL System Administration 1
Mesa Community College

Learning Objectives

Define open source software

Understand the freedoms, licensing, and development model

Explain what Linux is

The kernel, its history, and role in modern computing

Describe Linux distributions

How complete operating systems are built from Linux

Understand Red Hat Enterprise Linux

RHEL's role, features, and enterprise value proposition

We have four key learning objectives today, each building on the previous. First, we'll define open source software - not just as "free software" but understanding the specific freedoms, the licensing models, and the collaborative development approach that makes it unique. Second, we'll explain what Linux actually is - specifically the kernel - its origins with Linus Torvalds, and why it's become foundational to modern computing infrastructure. Third, we'll describe Linux distributions and understand why we don't just "install Linux" but rather choose from many distributions that package Linux with additional software. Finally, we'll focus on Red Hat Enterprise Linux specifically - understanding what makes it an enterprise distribution, its relationship to Fedora and CentOS, and why organizations choose it for mission-critical workloads. Let's begin with open source.

What is Open Source?

Open Source Software is software with source code that anyone can inspect, modify, and enhance. It's developed collaboratively and distributed under licenses that grant specific freedoms to users.

Key Characteristics:

Source code is publicly available
Free to use, modify, and distribute
Community-driven development
Transparent and auditable

Not Just "Free":

"Free as in freedom, not just free as in beer"
Companies can sell support and services
Commercial use is typically allowed
Different licenses have different terms

Open source software is fundamentally about access and freedom. Unlike proprietary software where the source code is secret, open source makes the code available to everyone. You can read it, learn from it, modify it, and share your modifications. This transparency is valuable for security - many eyes can find bugs - and for learning. But open source isn't just about free cost. We often say "free as in freedom, not free as in beer." The freedoms matter more than the price. Companies like Red Hat build successful businesses around open source by providing support, integration, and expertise. The collaborative development model means thousands of developers worldwide contribute to major projects like Linux, often from competing companies who benefit from shared infrastructure. Different open source licenses have different requirements - some require you to share modifications, others don't. Understanding this helps you navigate the open source ecosystem professionally.

The Four Essential Freedoms

Defined by the Free Software Foundation

Freedom to Run - Use the software for any purpose, without restrictions

Freedom to Study - Examine the source code and learn how it works

Freedom to Redistribute - Share copies with others

Freedom to Modify - Improve the software and release your improvements

Note: These freedoms are guaranteed by open source licenses like the GPL, MIT, and Apache licenses.

The Free Software Foundation defined four essential freedoms that characterize truly free and open source software. They're numbered starting at zero, in programmer tradition. Freedom zero is the freedom to run the program for any purpose - no restrictions on who can use it or what for. Freedom one is the freedom to study how the program works - this requires access to source code. Freedom two is the freedom to redistribute copies - you can share the software with anyone. Freedom three is the freedom to modify the program and distribute your modifications. These freedoms are legally enforced through licenses. The GNU General Public License, or GPL, is particularly important in the Linux world - it's a "copyleft" license that requires derivative works to also be open source. Other licenses like MIT and Apache are more permissive, allowing proprietary derivatives. Understanding these freedoms helps you appreciate why open source has become so successful - it enables unprecedented collaboration while protecting users' rights.

Open Source Everywhere

Open source powers the modern digital world

Infrastructure

Linux runs 96% of top web servers, all top 500 supercomputers, and most cloud infrastructure

Mobile

Android (based on Linux) powers billions of smartphones worldwide

Web

Apache, Nginx, Node.js, and most web technologies are open source

Databases

MySQL, PostgreSQL, MongoDB - most databases are open source

Containers

Docker, Kubernetes, and the entire container ecosystem

AI/ML

TensorFlow, PyTorch, and most AI frameworks are open source

Open source isn't a niche movement - it powers the infrastructure of the modern world. Linux runs about 96% of the top million web servers and 100% of the top 500 supercomputers. Every major cloud provider - AWS, Azure, Google Cloud - runs Linux. Android, which runs on billions of phones, is based on the Linux kernel. The web technologies we use daily are overwhelmingly open source - web servers like Apache and Nginx, programming runtimes like Node.js, browsers like Firefox and Chromium. Most databases in production use are open source - MySQL, PostgreSQL, MongoDB. The container revolution was built on open source - Docker, Kubernetes, and the entire cloud-native ecosystem. Even cutting-edge AI is open source - TensorFlow, PyTorch, and many AI models. Understanding open source isn't optional for IT professionals; it's understanding how modern technology actually works.

What is Linux?

Linux is an open source operating system kernel - the core component that manages hardware resources and provides essential services for all other software.

"I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones."

— Linus Torvalds, 1991 (announcing Linux)

Key Point: Linux is technically just the kernel. What we commonly call "Linux" is actually GNU/Linux - the kernel plus GNU utilities and other software.

Linux is specifically the operating system kernel - the core software that manages your computer's hardware and provides services for applications. In 1991, a Finnish student named Linus Torvalds announced his hobby project - a free operating system kernel for personal computers. That humble beginning has become one of the most successful software projects in history. The famous quote on screen shows how unexpectedly successful Linux became. Technically, what we call "Linux" should be called "GNU/Linux." The Linux kernel alone isn't a complete operating system. The GNU Project, started by Richard Stallman in 1983, created the essential utilities, compilers, and tools that surround the kernel. When Torvalds created Linux, the GNU project had everything except a working kernel. Together, GNU and Linux formed a complete, free operating system. In everyday conversation, we say "Linux," but it's worth remembering the full picture.

The Linux Kernel

The heart of the operating system

Process Management

Creates, schedules, and terminates processes; manages CPU time allocation

Memory Management

Allocates RAM, handles virtual memory, manages swap space

Device Drivers

Interfaces with hardware - disks, network cards, USB devices, etc.

File Systems

Manages how data is stored and retrieved from storage devices

Networking

TCP/IP stack, network protocols, packet handling

Security

Access control, permissions, SELinux, namespaces for containers

The kernel is responsible for the most fundamental tasks of the operating system. Process management means the kernel creates and manages all running programs, deciding which process gets CPU time and when. Memory management involves allocating RAM to processes, implementing virtual memory so processes can use more memory than physically available, and managing swap space on disk. Device drivers are how the kernel talks to hardware - every piece of hardware in your system has a driver in or loadable by the kernel. File system support lets the kernel organize data on storage devices - Linux supports many file systems including ext4, XFS, and more. The networking stack implements TCP/IP and other protocols, handling all network communication. Security features include the basic Unix permission model, but also advanced features like SELinux for mandatory access control and namespaces that make containers possible. All of these components work together, hidden from users, to make everything else possible.

Linux History

1983

GNU Project started by Richard Stallman to create a free Unix-like OS

1991

Linux kernel announced by Linus Torvalds as a hobby project

1993

Debian and Slackware - first major distributions emerge

1994

Red Hat Linux founded, bringing commercial support to Linux

2003

RHEL launched as enterprise-focused distribution

2011

Linux 3.0 - powers Android, cloud computing takes off

Today

Linux 6.x - runs most of the world's infrastructure

Let's trace Linux's history. In 1983, Richard Stallman started the GNU Project to create a complete free operating system. By 1991, GNU had most components except a kernel. That year, Linus Torvalds announced Linux - his free kernel. Together, they formed a complete system. By 1993, people started packaging GNU/Linux into distributions - Debian and Slackware were pioneers. In 1994, Red Hat was founded, recognizing that businesses would pay for professional support around free software. This was a pivotal business model innovation. In 2003, Red Hat launched Red Hat Enterprise Linux as a distinct product focused on stability and enterprise support, separate from their community-focused distribution. Around 2011, with Linux 3.0, we see Linux powering Android's explosive growth and the rise of cloud computing. Today, Linux 6.x is the foundation of modern computing infrastructure. This history shows how a student's hobby project, combined with the GNU foundation and corporate support, became the world's most important operating system.

What is a Linux Distribution?

A Linux distribution (distro) is a complete operating system built on the Linux kernel, packaged with system utilities, libraries, a package manager, and often a desktop environment.

Applications
Web servers, databases, office software, etc.

Distribution Layer
Package manager, configuration, desktop environment

GNU Utilities & Libraries
Bash, coreutils, glibc, GCC

Linux Kernel
Hardware abstraction, process/memory management

You can't just "install Linux" - you install a Linux distribution. A distribution takes the Linux kernel and combines it with everything needed for a complete, usable operating system. This diagram shows the layers. At the bottom is the Linux kernel, providing hardware abstraction and core OS services. Above that are the GNU utilities and libraries - the essential tools like the bash shell, core file utilities, and the C library that almost everything depends on. The distribution layer adds the package management system for installing software, system configuration tools, and often a desktop environment for graphical use. At the top are applications - the software you actually use. Different distributions make different choices at each layer - which kernel version, which packages to include, how to configure the system, what desktop to use. These choices define the distribution's character and target audience. Understanding this layering helps you see how RHEL relates to other distributions - they share the kernel and many components but differ in packaging, configuration, and support.

Popular Distributions

🎩

Red Hat Family

RHEL, Fedora, CentOS Stream, AlmaLinux, Rocky Linux

Uses: RPM, DNF

🟠

Debian Family

Debian, Ubuntu, Linux Mint, Pop!_OS

Uses: DEB, APT

🦎

Other Major

SUSE, Arch Linux, Gentoo, Alpine

Various package systems

Why so many? Different distributions serve different needs - stability vs. cutting-edge, enterprise vs. hobbyist, minimal vs. full-featured, general purpose vs. specialized.

There are hundreds of Linux distributions, but they cluster into families. The Red Hat family uses RPM packages and the DNF package manager. This includes RHEL itself, Fedora as the community upstream, CentOS Stream as a development preview, and community rebuilds like AlmaLinux and Rocky Linux. RHEL skills transfer well across this family. The Debian family uses DEB packages and the APT package manager. Debian prioritizes stability and free software principles. Ubuntu, based on Debian, is extremely popular for desktops and servers. Linux Mint builds on Ubuntu for an even more user-friendly desktop. Other major distributions include SUSE popular in Europe, Arch Linux for users who want complete control, Gentoo for those who compile everything from source, and Alpine which is tiny and popular for containers. Why do we need so many? Different distributions serve different needs. Enterprise users want stability and support - that's RHEL. Developers might want cutting-edge software - that's Fedora. Minimalists might choose Alpine. The diversity is a strength of the Linux ecosystem.

Choosing a Distribution

Factor	Enterprise (RHEL)	Community (Fedora)	General (Ubuntu)
Release Cycle	~3 years (major)	~6 months	6 months / 2 years LTS
Support Length	10+ years	~13 months	5 years (LTS)
Software Age	Stable, tested	Cutting-edge	Moderate
Commercial Support	Yes (Red Hat)	Community only	Yes (Canonical)
Target Use	Production servers	Developers, testing	Desktops, servers
Cost	Subscription	Free	Free / Paid support

Pro Tip: Learn on Fedora or CentOS Stream, deploy on RHEL. The skills transfer directly.

When choosing a distribution, consider these factors. Release cycle affects how often you'll need to upgrade - RHEL has major releases roughly every three years, Fedora every six months. Support length matters for production systems - RHEL is supported for over ten years, while Fedora versions are supported for only about thirteen months. Software age is a trade-off: RHEL packages are older but thoroughly tested; Fedora packages are the latest versions but less proven. Commercial support matters when things go wrong at 3 AM - with RHEL, you can call Red Hat; with Fedora, you're on your own. Target use reflects these trade-offs: RHEL for production servers where stability is paramount, Fedora for development where you want new features. Cost differs too - RHEL requires a subscription, while Fedora is free. A practical approach for learners: develop skills on Fedora or CentOS Stream, which are free, and those skills transfer directly to RHEL when you work in enterprise environments.

What is RHEL?

Red Hat Enterprise Linux (RHEL) is a commercial Linux distribution developed by Red Hat, designed for enterprise computing with long-term support, stability, security, and professional services.

Enterprise Features:

10+ year support lifecycle
Rigorous testing and certification
Security patches and updates
Hardware/software certifications
Professional technical support

Business Value:

Predictable and stable platform
Reduced operational risk
Regulatory compliance support
Training and certification paths
Ecosystem of certified applications

Red Hat Enterprise Linux is where open source meets enterprise requirements. It's built from open source components but packaged, tested, and supported for mission-critical business use. The enterprise features address what businesses need. The 10+ year support lifecycle means you can deploy RHEL and receive security updates for a decade - crucial for systems that can't be upgraded frequently. Rigorous testing means packages are thoroughly validated before release. Security patches are provided promptly when vulnerabilities are discovered. Hardware and software certifications ensure your stack is tested together. Professional support means when production systems fail, you have experts to call. The business value goes beyond technical features. Predictability lets you plan infrastructure without surprise changes. Reduced risk comes from the testing and support. Regulatory compliance - for industries like healthcare and finance - is supported with documentation and certifications. The training and certification ecosystem, including the RHCSA exam you may be preparing for, creates a pool of skilled professionals. And certified applications mean your software vendors officially support running on RHEL.

The Red Hat Ecosystem

Fedora
Upstream innovation

CentOS Stream
Development preview

RHEL
Enterprise production

← Innovation flows → Stability increases →

Development Flow: Features are developed in Fedora → tested in CentOS Stream → stabilized in RHEL. This ensures innovation while maintaining enterprise reliability.

RHEL doesn't exist in isolation - it's part of an ecosystem that balances innovation with stability. Fedora is the upstream community distribution where new features are developed and tested first. It's cutting-edge, with new releases every six months. Features that prove successful in Fedora are candidates for future RHEL versions. CentOS Stream sits between Fedora and RHEL. It's a rolling preview of what the next RHEL minor release will look like. Developers and partners use CentOS Stream to prepare for upcoming RHEL changes. It's also where community members can contribute directly to what becomes RHEL. RHEL itself is the stable, supported enterprise product. By the time features reach RHEL, they've been proven in Fedora and refined in CentOS Stream. This flow - innovation in Fedora, development preview in CentOS Stream, production stability in RHEL - lets Red Hat move quickly on innovation while maintaining the reliability enterprises require. Understanding this ecosystem helps you know where to test new features versus where to run production workloads.

Why Organizations Choose RHEL

🔒 Security

SELinux, security updates, vulnerability response team, FIPS certification, Common Criteria

⚙️ Stability

Consistent ABI, backported fixes without breaking changes, predictable release cycle

🎓 Certifications

Hardware certifications, ISV application certifications, cloud provider certifications

📞 Support

24/7 technical support, knowledge base, customer portal, dedicated account teams

🌐 Hybrid Cloud

Consistent platform across on-premises, public cloud, and edge deployments

Organizations choose RHEL for specific, business-critical reasons. Security is paramount - RHEL includes SELinux for mandatory access control, has a dedicated security response team, and achieves certifications like FIPS for government use and Common Criteria for international security standards. Stability means the application programming interfaces remain consistent - you won't have software break when you apply updates. Red Hat backports security fixes without changing behavior. Certifications matter because hardware vendors test their equipment with RHEL, software vendors certify their applications on RHEL, and cloud providers officially support RHEL images. When your whole stack is certified together, you eliminate a category of support problems. Professional support means having experts available when critical systems fail. The hybrid cloud story is increasingly important - RHEL runs identically on-premises, in AWS, Azure, Google Cloud, and at the edge, letting organizations standardize on one platform everywhere. These capabilities justify the subscription cost for organizations running serious workloads.

RHEL Subscriptions

What You Get:

Access to RHEL software
Security and bug fix updates
Technical support (tier varies)
Customer Portal and Knowledgebase
Red Hat Insights (analytics)
Access to partner ecosystem

Free Options:

Developer Subscription - free for individual developers (up to 16 systems)
CentOS Stream - free development preview
Fedora - free community upstream
RHEL free tier - cloud marketplace options

Student/Developer Access: Register at developers.redhat.com for a free individual developer subscription to RHEL.

RHEL uses a subscription model - you're paying for ongoing support, updates, and access to the platform. A subscription includes access to download RHEL, continuous security and bug fix updates, technical support at a level matching your subscription tier, access to the Customer Portal with documentation and knowledge base articles, Red Hat Insights for system analytics and recommendations, and access to certified applications from the partner ecosystem. But you don't need to pay to learn. Red Hat offers a free Developer Subscription for individual developers, covering up to 16 systems - perfect for learning and personal projects. CentOS Stream provides a free development preview of RHEL. Fedora provides free access to the cutting-edge upstream. Major cloud providers offer RHEL images, sometimes with free tier options. For this course, I recommend registering at developers.redhat.com for a free developer subscription. This gives you real RHEL to practice on, not a rebuild or approximation. The skills you develop transfer directly to production enterprise environments.

Key Takeaways

Open Source provides freedom to use, study, modify, and share software - powering most modern infrastructure

Linux is the kernel that manages hardware; combined with GNU utilities, it forms a complete OS

Distributions package Linux with software, tools, and configuration for different use cases

RHEL is the enterprise distribution providing stability, security, support, and certifications

Let's summarize what we've learned. Open source is more than free software - it's a development model based on transparency, collaboration, and user freedom. The four freedoms to run, study, modify, and share have enabled unprecedented innovation and now power most of the world's computing infrastructure. Linux is the kernel created by Linus Torvalds that, combined with GNU utilities, forms the foundation of thousands of distributions. Understanding that Linux is technically just the kernel helps you understand how distributions work. Distributions package Linux with all the software, configuration, and tools needed for specific purposes. Different distributions serve different needs - from cutting-edge development to rock-solid enterprise production. Red Hat Enterprise Linux is where open source meets enterprise requirements. It provides the stability, security, support, and certifications that mission-critical business workloads require. The subscription model funds ongoing development, support, and the broader open source ecosystem. For discussion, consider how this knowledge applies to your future work. Understanding these foundations will make you a more effective Linux administrator. Next module, we'll get hands-on with RHEL installation and first steps.

DISCUSSION QUESTIONS

How does the open source development model differ from proprietary software?
Why might an organization choose RHEL over a free distribution?
What role does the Fedora → CentOS Stream → RHEL pipeline serve?
How do the four freedoms benefit enterprise users?

Next: Accessing the Command Line

Introduction toOpen Source & Linux