Linux for Networking Professionals

Rob VandenBrink

• Publisher: Packt Publishing
• Year: 2021
• eBook ISBN: 9781800204652
• Edition: 1
• Topic: Computer Science
• Subtopic: Computer Networking
• Index: Computer Science

Get to grips with the most common as well as complex Linux networking configurations, tools, and services to enhance your professional skillsKey Features• Learn how to solve critical networking problems using real-world examples• Configure common networking services step by step in an enterprise environment• Discover how to build infrastructure with an eye toward defense against common attacksBook DescriptionAs Linux continues to gain prominence, there has been a rise in network services being deployed on Linux for cost and flexibility reasons. If you are a networking professional or an infrastructure engineer involved with networks, extensive knowledge of Linux networking is a must.This book will guide you in building a strong foundation of Linux networking concepts. The book begins by covering various major distributions, how to pick the right distro, and basic Linux network configurations. You'll then move on to Linux network diagnostics, setting up a Linux firewall, and using Linux as a host for network services. You'll discover a wide range of network services, why they're important, and how to configure them in an enterprise environment. Finally, as you work with the example builds in this Linux book, you'll learn to configure various services to defend against common attacks. As you advance to the final chapters, you'll be well on your way towards building the underpinnings for an all-Linux datacenter.By the end of this book, you'll be able to not only configure common Linux network services confidently, but also use tried-and-tested methodologies for future Linux installations.What you will learn• Use Linux as a troubleshooting and diagnostics platform• Explore Linux-based network services• Configure a Linux firewall and set it up for network services• Deploy and configure Domain Name System (DNS) and Dynamic Host Configuration Protocol (DHCP) services securely• Configure Linux for load balancing, authentication, and authorization services• Use Linux as a logging platform for network monitoring• Deploy and configure Intrusion Prevention Services (IPS)• Set up Honeypot solutions to detect and foil attacksWho this book is forThis book is for IT and Windows professionals and admins looking for guidance in managing Linux-based networks. Basic knowledge of networking is necessary to get started with this book.

Section 1: Linux Basics

This section outlines the various Linux options available to the reader, and why they might select Linux to deliver various network functions or services. In addition, basic Linux network configuration is covered in some depth. This section sets the stage for all the subsequent chapters.

This part of the book comprises the following chapters:

• Chapter 1, Welcome to the Linux Family
• Chapter 2, Basic Linux Network Configuration and Operations – Working with Local Interfaces

Chapter 1: Welcome to the Linux Family

This book explores the Linux platform and various Linux-based operating systems – in particular, how Linux can work well for networking services. We'll start by discussing some of the history of the operating system before looking at its basic configuration and troubleshooting. From there, we'll work through building various network-related services on Linux that you may commonly see in most organizations. As we progress, we'll build real services on real hosts, with an emphasis on securing and troubleshooting each service as we go. By the time we're done, you should be familiar enough with each of these services to start implementing some or all of them in your own organization. As they say, every journey begins with a single step, so let's take that step and start with a general discussion of the Linux platform.

In this chapter, we'll start our journey by exploring Linux as a family of operating systems. They're all related, but each is unique in its own way, with different strengths and features.

We'll cover the following topics:

• Why Linux is a good fit for a networking team
• Mainstream data center Linux
• Specialty Linux distributions
• Virtualization
• Picking a Linux distribution for your organization

Why Linux is a good fit for a networking team

In this book, we'll explore how to support and troubleshoot your network using Linux and Linux-based tools, as well as how to securely deploy common networking infrastructure on Linux platforms.

Why would you want to use Linux for these purposes? To begin with, the architecture, history, and culture of Linux steers administrators toward scripting and automating processes. While carrying this to extremes can get people into funny situations, scripting routine tasks can be a real time-saver.

In fact, scripting non-routine tasks, such as something that needs doing once per year, can be a lifesaver as well – it means that administrators don't need to relearn how to do that thing they did 12 months ago.

Scripting routine tasks is an even bigger win. Over many years, Windows administrators have learned that doing one task hundreds of times in a Graphical User Interface (GUI) guarantees that we misclick at least a few times. Scripting tasks like that, on the other hand, guarantees consistent results. Not only that, but over a network, where administrators routinely perform operations for hundreds or thousands of stations, scripting is often the only way to accomplish tasks at larger scales.

Another reason that network administrators prefer Linux platforms is that Linux (and before that, Unix) has been around since there were networks to be a part of. On the server side, Linux (or Unix) services are what defined those services, where the matching Windows services are copies that have mostly grown to feature parity over time.

On the workstation side, if you need a tool to administer or diagnose something on your network, it's probably already installed. If the tool that you seek isn't installed, it's a one-line command to get it installed and running, along with any other tools, libraries, or dependencies required. And adding that tool does not require a license fee – both Linux and any tools installed on Linux are (almost without exception) free and open source.

Lastly, on both the server and desktop side, historically, Linux has been free. Even now, when for-profit companies have license fees for some of the main supported distributions (for instance, Red Hat and SUSE), those companies offer free versions of those distributions. Red Hat offers Fedora Linux and CentOS, both of which are free and, to one extent or another, act as test-bed versions for new features in Red Hat Enterprise Linux. openSUSE (free) and SUSE Linux (chargeable) are also very similar, with the SUSE distribution being more rigorously tested and seeing a more regular cadence for version upgrades. The enterprise versions are typically term-licensed, with that license granting the customer access to technical support and, in many cases, OS updates.

Many companies do opt for the licensed enterprise-ready versions of the OS, but many other companies choose to build their infrastructures on free versions of OpenSUSE, CentOS, or Ubuntu. The availability of free versions of Linux means that many organizations can operate with substantially lower IT costs, which has very much influenced where we have gone as an industry.

Why is Linux important?

Over the years, one of the jokes in the information technology community is that next year was always going to be the year of the Linux desktop – where we'd all stop paying license fees for desktops and business applications, and everything would be free and open source.

Instead, what has happened is that Linux has been making steady inroads into the server and infrastructure side of many environments.

Linux has become a mainstay in most data centers, even if those organizations think they are a Windows-only environment. Many infrastructure components run Linux under the covers, with a nice web frontend to turn it into a vendor solution. If you have a Storage Area Network (SAN), it likely runs Linux, as do your load balancers, access points, and wireless controllers. Many routers and switches run Linux, as do pretty much all the new software-defined networking solutions.

Almost without fail, information security products are based on Linux. Traditional firewalls and next-generation firewalls, Intrusion Detection and Prevention Systems (IDS/IPS), Security Information and Event Management (SIEM) systems, and logging servers – Linux, Linux, Linux!

Why is Linux so pervasive? There are many reasons:

• It is a mature operating system.
• It has an integrated patching and updating system.
• The basic features are simple to configure. The more complex features on the operating system can be more difficult to configure than on Windows though. Look ahead to our chapter on DNS or DHCP for more information.
• On the other hand, many features that might be for sale products in a Windows environment are free to install on Linux.
• Since Linux is almost entirely file-based, it's fairly easy to keep it to a known baseline if you are a vendor who's basing their product on Linux.
• You can build just about anything on top of Linux, given the right mix of (free and open source) packages, some scripting, and maybe some custom coding.
• If you pick the right distribution, the OS itself is free, which is a great motivator for a vendor trying to maximize profit or a customer trying to reduce their costs.

If the new Infrastructure as Code movement is what draws you, then you'll find that pretty much every coding language is represented in Linux and is seeing active development – from new languages such as Go and Rust, all the way back to Fortran and Cobol. Even PowerShell and .NET, which grew out of Windows, are completely supported on Linux. Most infrastructure orchestration engines (for instance, Ansible, Puppet, and Terraform) started on and supported Linux first.

On the cloud side of today's IT infrastructure, the fact that Linux is free has seen the cloud service providers push their clients toward that end of the spectrum almost from the start. If you've subscribed to any cloud service that is described as serverless or as a Service, behind the scenes, it's likely that that solution is almost all Linux.

Finally, now that we've seen the server and infrastructure side of IT move toward Linux, we should note that today's cell phones are steadily becoming the largest desktop platform in today's computing reality. In today's world, cell phones are generally either iOS- or Android-based, both of which are (you guessed it) Unix/Linux-based! So, the year of the Linux desktop has snuck upon us by changing the definition of desktop.

All of this makes Linux very important to today's networking or IT professionals. Thi...

Table of contents

• Linux for Networking Professionals
• Contributors
• About the author
• About the reviewer
• Preface
• Section 1: Linux Basics
• Chapter 1: Welcome to the Linux Family
• Chapter 2: Basic Linux Network Configuration and Operations – Working with Local Interfaces
• Section 2: Linux as a Network Node and Troubleshooting Platform
• Chapter 3: Using Linux and Linux Tools for Network Diagnostics
• Chapter 4: The Linux Firewall
• Chapter 5: Linux Security Standards with Real-Life Examples
• Section 3: Linux Network Services
• Chapter 6: DNS Services on Linux
• Chapter 7: DHCP Services on Linux
• Chapter 8: Certificate Services on Linux
• Chapter 9: RADIUS Services for Linux
• Chapter 10: Load Balancer Services for Linux
• Chapter 11: Packet Capture and Analysis in Linux
• Chapter 12: Network Monitoring Using Linux
• Chapter 13: Intrusion Prevention Systems on Linux
• Chapter 14: Honeypot Services on Linux
• Assessments
• Other Books You May Enjoy