The Enterprise Linux Administrator: Journey to a New Linux Career

Table of Contents
About the Author
About the Technical Reviewer
Acknowledgments
Introduction
Part I: Requirements and Linux Background
	Chapter 1: Requirements
		Information Technology Basics
			Hardware
				Required Knowledge
			Software
				Required Knowledge
			Networking
				Required Knowledge
		Further Reading
			Hardware
				POST
				Boot Process
				Computer Memory
				System Buses
			Software
				The Operating System
				Kernel
				Device Driver
			Network
				Computer Networking
				The OSI Model
			Storage
		Further Study
			Free Online Courses
			Paid-For Online Courses
			Hardware and Software
				Basic Hardware Courses
			Networking
		Summary
	Chapter 2: Origins and Brief History
		Unix and Linux History
			Unix
				Multics
				Early Unix
				Unix 2, Love Ken
				First Commercially Available Unix
				Unix Limitation
				Unix Variations
				Unix Standards
				Unix Growth in the 1990s
			Linux History
				Linus Torvalds
				Kernel
				Very Early Linux
				The Kernel Is Not Enough
				Free Software Foundation
				OpenSource
				Enterprise Linux
		Evolution of Linux
			Debian
			Important Milestones of Linux
				Kernel 2.0
				Linux Desktop
				Desktop Wars
				Dell, Oracle, and Red Hat Started to Grow
				Kernel 3.0
				Systemd
				Android and Ubuntu Increased in Popularity
				Kernel 4.0
				Kernel 5.0
			Linux Now and in the Future
		Summary
	Chapter 3: Linux Explained
		Linux Operating System
			Kernel
				Monolithic and Modular
				Kernel Architecture
					Functionality Pillars
					Layers
					Kernel Map
				System Calls
					Process Control
					File Management
					Device Management
					Information Management
					Communication
					Protection
			Initial Ramdisk
				Missing Drivers
			Everything Is a File, Mostly
			Utilities
				Shell
				Other Utilities
				Desktops
		Common Distributions
			Differences
				Package Management
			Upstream Projects
			Unique Distributions
		Operating System Differences
			Windows
				Not OpenSource
			Windows vs. Linux
		Uses of Linux
			Servers
			Desktop
			Mobile Devices
			IoT
			Future Linux
		Summary
Part II: Getting Started
	Chapter 4: Installing Linux for the First Time
		Where to Get Linux
			OpenSource and Free Software
			Enterprise Linux
				Red Hat
					Red Hat Enterprise Linux
				Canonical
				Ubuntu
				SUSE
				SLES Server and Desktop
			Community
				Fedora
				OpenSUSE
				Ubuntu
		Virtualization
			What Is Virtualization?
			Types of Virtualization
				Hardware Requirement
				BIOS Requirements
				Windows Virtualization
					VirtualBox
					Exercise
				Linux Virtualization
					KVM
					Exercise
			Creating Virtual Machines
				VirtualBox
					Exercise
				KVM
					Exercise
		Installation Media
			Burn Image
			USB Drive
				MediaWriter
				Ventoy
				Learning Exercise
			Network Install
		Installing Linux
			Lab Environment
				Hypervisor
				Installation Media
				Virtual Machine Sizing
		Ubuntu
			Installation Media
			Basic Installation
				Create a Virtual Machine
				Ubuntu Server Installation
			Basic Exercise
				Virtual Machine
				Ubuntu Server
				Exercise Outcome
			Custom Installations
			Optional Custom Exercise
				Virtual Machine
				Ubuntu Server
		Fedora Server
			Installation Media
			Basic Installation
				Create a Virtual Machine
				Fedora Server Installation
			Basic Exercise
				Virtual Machine
				Fedora Server
				Exercise Outcome
			Custom Installations
			Optional Custom Exercise
				Fedora Server
		OpenSUSE
			Installation Media
			Basic Installation
				Create a Virtual Machine
				OpenSUSE Server Installation
			Basic Exercise
				Virtual Machine
				OpenSUSE Server
				Exercise Outcome
			Custom Installations
			Optional Custom Exercise
				OpenSUSE Server
		Upgrading Linux
			Upgrade vs. Migration
			Before Upgrading
				Backup
				Check Disk Space
				Confirm Your Version Can Be Upgraded
			What Distributions Can Be Upgraded
				Ubuntu
				Fedora
				OpenSUSE
			Exercise
				Upgrade Ubuntu
				Upgrade Fedora
				Upgrade OpenSUSE
		Summary
	Chapter 5: Using Linux for the  First Time
		Accessing Linux
			Console
				Virtualization
				Hardware Consoles
				Why Is the Console Important?
			SSH
				Logging into Another Linux System
				Putty
				WinSCP
				SSH Configuration Files
					sshd_config
					SSH Keys
			Web Console
				Installing Cockpit
				Accessing Cockpit
			Exercise
				Enable Passwordless ssh
				Configure Cockpit
		Command Line
			Finding Help
				Man Pages
			Navigating the Filesystem
				Listing Files
				Changing Directories
				Don't Know Where Are You?
				Summary of the Very Basics
				Finding Files
				Editing Files
					Desktop Utilities
					Command-Line Editing
					Using vi and vim
						Command Mode
						Edit Mode
						Example
			Command-Line Shortcuts
				Alias
				Scripts
			Different Commands in Different Distributions
				Fedora – dnf
				Ubuntu – apt
				OpenSUSE – zypper
			Exercise
				Finding Files
					Old Files
					Files with Permissions
				Creating File with Content
				Installing a Package
		Desktop Basics
			Installing Different Desktops
				Fedora Server
				Ubuntu Server
				OpenSUSE Server
			Enabling and Disabling Desktops
				Enable Graphical Desktop
				Disable Graphical Desktop
				Why Not Install Desktop During Installation
			Exercise
				Remove Cinnamon
				Install the MATE Desktop
				Optional – Try Another Desktop
		Summary
	Untitled
Part III: Basic Configuration
	Chapter 6: Access Control
		SSH and SSHD Configuration
			Configuration Files
				ssh_config
				sshd_config
				ssh_config.d and sshd_config.d
				Important ssh Parameters
					PermitRootLogin
					PasswordAuthentication
					Port
					ListenAddress
					MaxAuthTries
					UsePam
					AllowUsers and DenyUsers
					AllowGroups and DenyGroups
					LogLevel
			Default Configuration
				Fedora
				Ubuntu
				OpenSUSE
			SSH Service
				Test Syntax
				Restart sshd
				Check Status
			Debugging ssh Issues
				Service Dead
				Syntax Error
				Firewall Rule
				Network and Port
				Incorrect Allow or Deny
			Exercise
				Change Port
				Create custom_sshd.conf
		Users and Groups
			Local Users and Groups
				Configuration Files
				Creating Users
				Setting a Password
				Modifying a User
				Removing Users
				User Password Management
				Creating Groups
				Modifying a Group
				Removing Groups
			Remote Users and Groups
				Windows Active Directory
				FreeIPA
				Using Remote Users and Groups
					Windows Active Directory
					IPA-Client
			Sudo
				Sudo Commands and Tools
				Managing Sudo
			Exercise
				Create a New User
				Create a New Group
				Elevate Permissions
		File and Directory Permissions
			Understanding Linux Permissions
				Directory Listing Explained
			Managing File and Directory Permissions
				Chmod
					Example
				Chown
					Example
			ACLs
				getfacl
				setfacl
					Example
			Exercise
				File and Directory Permissions
				ACLs
		Summary
	Chapter 7: Package Installation
		Installing Packages
			Package Management Systems
				Fedora
					Command Line
						dnf
						Using dnf
						Getting More out of dnf
					Desktop
				Ubuntu
					Command Line
						apt
						Using apt
						Getting More out of apt
					Desktop
				OpenSUSE
					Command Line
						Zypper
						Using Zypper
						Getting More out of Zypper
					Desktop
				Exercise
					Installing Packages via Command Line
					Removing Packages Using the Desktop
			Manual Package Installation
				RPM
					Installing an rpm Package
					Uninstalling an rpm Package
					Learning More About rpm
				Deb
					Installing a “deb” Package
					Uninstalling a “deb” Package
					Learning More About dpkg
				Installing Manually Using dnf, apt, and zypper
					Dependencies
					Installing a Package Using a Package Installation Utility
					Removing a Package Using a Package Installation Utility
				Exercise
					Install figlet Manually
					Remove figlet
			Repository Configuration
				Fedora
					Example of a Repository File
					Creating Your Own Repository File
					List Available Repositories
				Ubuntu
					Example of a repository file
					Repository Lines Explained
					Creating Your Own Repository File
					List Available Repositories
				OpenSUSE
					Example of a Repository File
					Creating Your Own Repository File
					List Available Repositories
		System Patching
			Errata
				Community vs. Enterprise
			System Updates
				Fedora
					Explanation
				Ubuntu
					Explanation
				OpenSUSE
					Explanation
			Rollback
				Fedora
				Ubuntu
				OpenSUSE
				Virtual Machine Snapshots
				Creating Snapshots
					libvirt Snapshots
					Roll Back a Snapshot with libvirt
			Exercise
				Update Your Linux Environments
				Rolling Back
					Prerequisite
					Tasks
		Summary
	Chapter 8: Network Configuration
		Network Basics in Linux
			Network Configuration Using Command Line
				Current System Networking Information
					ifconfig
					ip
					Getting More Information
				Network Manager
				Configure Your Interface Adapter
					Set Network During Installation
					Manual Configuration
						Fedora
						Ubuntu
						openSUSE
							Additional Parameters
							Applying Network Configuration
					Network Manager
						Managed or Not
							Fedora
							Ubuntu
							OpenSUSE
						Change Network Configuration with NetworkManager
			Network Configuration Using Textual Interfaces
				NetworkManager
			Network Configuration with Desktop
				Fedora
				Ubuntu
				OpenSUSE
			Exercise
				Fedora
				Ubuntu
				OpenSUSE
		Network Tools
			Default Tools Available
				Ping
				ss
				dig
			Exercise
				Prerequisites
				Network Testing
		Summary
	Chapter 9: Disk Configuration
		Disk Management
			Disk Layers
			Tools Available
				Showing Disks Available
					/proc/partitions File
					lsblk
					Graphical Tools
				Disk Names
				Adding Disks
				Disk Partition Tooling
					fdisk
					parted
				Graphical
					Fedora
					Ubuntu
					OpenSUSE
			Exercise
				Prerequisites
				Create a Partition with “fdisk”
				Create a Partition with “parted”
				Create a Partition with “YaST Partitioner”
			LVM
				Installing LVM
					Package Name
				LVM Utilities
				Create
					Physical Volume
					Volume Group
					Logical Volumes
				Extending LVM
					Extending Physical Volumes
					Extending Volume Groups
					Extending Logical Volumes
				Migrate
				Destroy
					Delete Physical Volumes
					Delete Logical Volumes
					Delete Volume Groups
				Disaster Recovery
				RAID, Mirror, and HA
			Exercise
				Add Disks
				Install LVM
				Create LVM Components
				Delete and Recover
		Filesystem Management
			Filesystem Types
			Checking Disk Filesystem
			Creating
			Mounting Filesystems
				Mounts Persistent Across Reboots
			Resizing
				xfs Cannot Shrink
			Directory Hierarchy
			Exercise
				Create Filesystem
				Mount Filesystem
		Summary
	Chapter 10: Service Management
		Basic Service Management
			Service Management Utilities
				chkconfig
				systemctl
				Web Console
				Example Service
			Starting a Service
				Command Line
				Cockpit Web Console
			Stopping a Service
				Command Line
				Cockpit Web Console
			Viewing the Status of a Service
				Command Line
				Cockpit Web Console
			Enabling/Disabling a Service
				Command Line
				Cockpit Web Console
			Exercise
				Prerequisites
					Cockpit
					Apache Web Server
				Manage httpd Service
					Enable and Start
					Confirm Service Is Started
					Stop and Disable
		systemd
			Configuration Files
				Configuration File Types
				Example Configuration File
				Configuration File Locations
					Changing to and from Graphical Desktops
			Utilities
				systemctl
				journalctl
				Other Useful Utilities
			Exercise
				Basic Service Management
				Check Your Default Target
		Creating a New Service
			Example Script
			Unit File
				Unit File Explained
					Unit Section
					Service Section
					Install Section
			Enable and Start Service
			Remove a Service
			Exercise
				Create a Script
				Create a Service
				Remove Your Service
		Summary
Part IV: Enterprise
	Chapter 11: Enterprise Linux Distributions
		Red Hat
			Brief History
				Upstream
			RHEL
				Red Hat Account
				Exercise
					Red Hat
				Installation Media
				Using Installation Media
				Virtual Machine
				Create a Virtual Machine
				RHEL Install
			Subscriptions and Support
				Subscribing a System
					Verify Subscriptions
					Register with Red Hat
					Attaching Subscriptions
					Unregister with Red Hat
			Estate Management Basics
				Estate Management Tools
					Red Hat Satellite Server
					Red Hat Automation Platform
			Training and Certifications
				RHCSA
				RHCE
				Expertise Exams
			Exercise
				Virtual Machine
				RHEL Server
				Register to Red Hat
		SUSE Linux Enterprise Server
			Brief History
				Upstream
			SLES
				SUSE Account
				Exercise
					SUSE
				Installation Media
				Using Installation Media
				Virtual Machine
				Create a Virtual Machine
				Installing SLES
			Subscriptions and Support
				Subscribing a System
					Verify Subscriptions
					Register with SUSE
				Verify the System Registered with SUSE
				Deregister with SUSE
			Estate Management Basics
				Estate Management Tools
					SUSE Manager
					SaltStack
			Training and Certifications
				SCA
				SCE
				Speciality Exams
			Exercise
				Virtual Machine
				SLES Server
		Ubuntu
			Brief History
				Upstream Is Enterprise
			Ubuntu
			Training and Certifications
				Ubuntu Account
				Exercise
					Ubuntu
			Ubuntu Installation
			Estate Management Basics
				Estate Management Tools
					Landscape
			Subscriptions and Support
				Subscribing a System
					Verify Subscriptions
					Register with Ubuntu
				Verify the System Registered with SUSE
				Detach from the Ubuntu Account
		Summary
	Chapter 12: Example Use Cases for Linux
		Building a Web Server
			Web Server Options
				Apache httpd
				Nginx
			Web Server Configuration Overview
				Use Case Overview
				Design Decision
				Linux Distribution
			Linux Installation and Configuration
				User Account
				Subscribe to an Ubuntu Account
			Web Server Package Installation
				Firewalld
				Apache2
			Configuration Files
				apache2.conf
				Included Configuration
				Website Configuration
					Create Directories
					Create Website Files
					Site Configuration Files
			Firewall Configuration
				Firewall Status
				Opening Ports
				Reload Firewall Configuration
				Verify Configuration
			SELinux Configuration
				No SELinux on Ubuntu
				AppArmor
				Install SELinux
				Activate SELinux
				SELinux Permissive First
				SELinux Relabel
				SELinux Enforcing (Optional)
				Set SELinux Labels
			Exercise
				Prerequisites
				Build a Web Server
				Success Criteria
		Building a File Server
			NFS vs. Samba
			File Server Configuration Overview
				Use Case Overview
				NFS Solution
				Linux Distribution
			Linux Installation and Configuration
				User Account
				Subscribe to a Red Hat Account
			NFS Server Package Installation
				Firewalld
				nfs-utils
			Firewall Configuration
				Firewall Status
				Opening NFS Ports
				Reload Firewall Configuration
				Verify Configuration
			SELinux Configuration
				SELinux Enforcing
			Disk to Share
				Disk
			NFS Server Configuration
				Configuration File
					/etc/exports
					nfs-server Service
					Validate Configuration
					Test NFS Mounts
						NFS Server
						Web Server
			Exercise
				Prerequisites
				NFS Server
				Web Server
				Success Criteria
		Summary
	Chapter 13: Security
		Firewall
			Command-Line Configuration
				Iptables
				Firewalld
					Service
					Status
					Adding Ports and Services
					Removing Ports and Services
					Cheatsheet
			Web UI Configuration
				Using Cockpit
			Exercise
				Firewall Status
				Add to Firewall
				Learning More About Firewall Services
				Remove from Firewall
		SELinux
			SELinux Modes
			Command-Line Configuration
				SELinux Mode
					SELINUX
					SELINUXTYPE
				SELinux Commands
					getenforce
					setenforce
					Listing SELinux Labels
				SELinux Context Labels
					Listing Context Labels
					Setting Context Labels
					chcon
					semanage
				SELinux Booleans
					getsebool
					setsebool
				SELinux Debugging
					Journalctl
					Ausearch
					/var/log/messages
				Cheatsheet
			Exercise
				Setting SELinux Modes
				List SELinux Booleans
				Web Server and SELinux
		Hardening
			Hardening Standards
				Center for Internet Security (CIS)
				Security Technical Implementation Guide (STIG)
			Compliance Scanning
				OpenSCAP
					Installation
					Running Vulnerability Scans
					OpenSCAP Profiles
						Available Profiles
						Profile Information
						Running a Scan with a Profile
						Remediation
						Automated Remediation
			Exercise
				Prerequisites
				Compliance Scans
				Remediate
		Encryption
			How Does Encryption Work
			Linux Encryption
				SSH Keys
					Asymmetric Encryption
					Generate ssh Keys
						Different Algorithm
					Using ssh Keys
						Manual Configuration
				Disk Encryption
					Cryptsetup
					Create a LUKS Encrypted Disk
					Decrypting a LUKS Disk
					Encrypted Disk Status
					Formatting an Encrypted Disk
					Mounting an Encrypted Disk
					Persistent Mounting
				Network Encryption
					VPN
					Create a VPN Connection
				Certificates
					What Are Certificates Used For
					SSL and TLS
					Certificate Authority
					Manual Certificate Generation
					Automated Certificate Generation
			Exercise
				SSH Keys
				Encrypted Disk
				Generate a csr
		Summary
	Chapter 14: High Availability
		Clustering
			Types
				High Availability
				Load Balancing
				Distributed
				High Performance
			Cluster Concepts
		Enterprise Linux Clustering
			Projects
				Corosync
				Pacemaker
			RHEL Cluster Example
				Prerequisites
					Configuration Requirements
						Static IP Addresses
						Hostname Resolution
						NTP
						Communication Between Nodes
						Subscribe to Subscription
				Cluster Installation
					Install Packages
					Firewall Rules
					Cluster User Account
					Cluster Services
					Cluster Setup
						Authorize Nodes
						Form the Cluster
					Cluster Quorum
					Cluster Status
				Fencing
					KVM Fencing
					Node Fencing
					Cluster Resources
						Virtual IP Address
						Web Server
					Fixing the Cluster
						Removing resource
						Group Resources
					Cluster Status
			Cluster Troubleshooting
				Logs
				Official Documentation
				Official Training
			Exercise
				Prerequisites
				Build a Cluster
				Success Criteria
		Summary
	Chapter 15: Scripting and Automation
		Shell Scripting
			Linux Shell
				Shell Environments
				Check Your Shell Environment
				Change Shell Environments
			Shell Scripting Basics
				Before Writing a Script
					Is a Script Needed?
					Does This Already Exist?
					Keep It Simple
				Script Structure
				Interpreters
				Variables
					Setting Variables
					Variable Names
					Special Variables
					Variable Arithmetic
				Script Body
					Conditionals
					Conditional Operands
					Loops
			Examples
				Create Directory
				Package Installation
			Exercise
				Create Users
				Packages Managed
		Ansible
			Explained
				Control Node
				Managed Nodes
				Inventory
				Playbooks
				Roles
				Modules
				Plug-ins
				Collections
			Ansible Configuration
				Control Node
					Setup ssh Keys
					Ansible Configuration Files
						Hierarchy
				Creating Ansible Content
					Inventory File
					Playbook
						Execute Playbook
					Role
				Ansible Galaxy
				Variable Files
					Custom Variables
					Group_vars
					Host_vars
					Using Variables
				Ansible Documentation
			Exercise
				Ansible Environment
				Create a Playbook
				Create a Variable File
				Bonus Task
		Summary
	Chapter 16: Deployment at Scale
		Deployment Methods
			Kickstart
				Create Kickstart File
				Copy Kickstart File to Web Server
				Build a New System
				Official Documentation
			Image Cloning
			Kickstart vs. Cloning
			Exercise
				Prerequisite
				Create a Kickstart File
				Build RHEL 9 Using Kickstart
				Clone a VM
		Deployment Tools
			Enterprise Deployment Tools
				Foreman
				Red Hat Satellite Server
					Subscription Required
					Installing Red Hat Satellite Server
				Uyuni
				SUSE Manager
			Automation
				Ansible
					Red Hat Enterprise Version
					Community Ansible
				SaltStack
				Puppet
				Terraform
					How to Get Terraform
			Training and Certifications
				Red Hat
				SUSE
		Summary
Part V: Troubleshooting and Recovery
	Chapter 17: Troubleshooting Linux
		Logging
			Logs
				Where Logs Are Located
				Rsyslog
					Installation
					Configuration File
						Global Directives
						Templates
						Rules
				Verbosity
					Log Detail Levels
					Set Log Level
					Don’t Leave Debugging On
				Understanding Errors
				Tail Logs as You Work
			Journalctl
				Real-Time Messages
				Useful journalctl Commands
			Remote Logging
				Rsyslog as a Central Logging System
					Firewall
					SELinux
					rsyslog.conf
					Restart Service
				Forward Logs to Rsyslog server
					Restart Service
			Exercise
				Journalctl
				Logs
				Remote Logging
		Monitoring
			Process-Related Tools
				ps and top
					top
					ps
				pstree
			Disk-Related Tools
				lsblk
				blkid
				du
				df
			Network-Related Tools
				ss
				Additional Network Tools
			Performance Copilot
			Remote Monitoring
			Nagios
			Prometheus
		Finding Help
			Tools
				strace
				Manual Pages and Help
			Asking for Help
				Before Asking for Help
				Asking a Question the Right Way
					Be Very Clear
					Question Wording
				Example Questions
					Bad Question
					Good Question
			Getting Support
				Preempted Support
				Sosreport
		Summary
	Chapter 18: Recovering from Disaster
		Reinstalling
			Things to Consider
				Cattle vs. Pets
				Time to Build vs. Time to Troubleshoot
				Build from Code
				Knowing When to Start Over
		Recovering
			Single-User Mode
				RHEL
				Ubuntu
				SLES
			Emergency vs. Rescue Mode
			Using Rescue Disks
			Rescue Examples
				Root Password Reset
				Kernel Issues
					Use Old Kernel
					Rescue Disk and Install New Kernel
				Resolving Mount Issues
			Exercise
				Boot into Emergency Mode
				Boot into Rescue Mode
				Fix the Root Password
				Boot into a Second Kernel
		Summary
	Chapter 19: Backup and Restore
		Backups
			Backup Methods
				Filesystem Backups
					When to Back Up
					Tools
					What to Back Up
					Where to Back Up
					Network Considerations
					Network Mounts
				Virtual Machine Backups
					Snapshots
					Backup VM Files
				Storage Backups
			Backup Reports
		Restore
			What to Restore
			Test Restore
		Summary
Index