Arguably one of the most highly regarded and widely used enterprise-level operating systems available today is the Red Hat Enterprise Linux (typically shortened to RHEL and pronounced rell) distribution. Not only is it considered to be among the most stable and reliable operating systems, it is also backed by the considerable resources and technical skills of Red Hat, Inc. Red Hat Enterprise Linux 9 Essentials is designed to provide detailed information on the installation, use, and administration of the Red Hat Enterprise Linux 9 distribution. For beginners, the book covers topics such as operating system installation, the basics of the GNOME desktop environment, configuring email and web servers, and installing packages and system updates using App Streams. Additional installation topics, such as dual booting with Microsoft Windows, are also covered, together with all important security topics, such as configuring a firewall and user and group administration.
For the experienced user, topics such as remote desktop access, the Cockpit web interface, logical volume management (LVM), disk partitioning, swap management, KVM virtualization, Secure Shell (SSH), Linux Containers, and file sharing using both Samba and NFS are covered in detail to provide a thorough overview of this enterprise class operating system.
Author(s): Neil Smyth
Publisher: Payload Media
Year: 2023
Language: English
Pages: 223
1. Introduction 1
1.1 Superuser Conventions 1
1.2 Opening a Terminal Window 2
1.3 Editing Files 3
1.4 Feedback 4
1.5 Errata 5
2. A Brief History of Red Hat Linux 7
2.1 What exactly is Linux? 7
2.2 UNIX Origins 7
2.3 Who Created Linux? 7
2.4 The Early Days of Red Hat 8
2.5 Red Hat Support 8
2.6 Open Source 9
2.7 The Fedora Project 9
2.8 CentOS Stream - The Free Alternative 9
2.9 Summary 9
3. Installing RHEL 9 on a Clean Disk Drive 11
3.1 Obtaining the RHEL 9 Installation Media 11
3.2 Writing the ISO Installation Image to a USB Drive 12
3.2.1 Linux 12
3.2.2 macOS 13
3.2.3 Windows/macOS 14
3.3 Installing Red Hat Enterprise Linux 9 15
3.4 Partitioning a Disk for RHEL 9 20
3.5 Disk Encryption 22
3.6 User Settings 23
3.7 Registering the System 23
3.8 The Physical Installation 24
3.9 Final Configuration Steps 24
3.10 Installing Updates 25
3.11 Displaying Boot Messages 26
3.12 Summary 26
4. Dual Booting RHEL 9 with Windows 29
4.1 Partition Resizing 29
4.2 Changing the Default Boot Option 31
4.3 Accessing the Windows Partition from RHEL 9 32
4.4 Summary 33
5. Allocating Windows Disk Partitions to RHEL 9 35
5.1 Unmounting the Windows Partition 35
5.2 Deleting the Windows Partitions from the Disk 35
5.3 Formatting the Unallocated Disk Partition 38
5.4 Mounting the New Partition 38
5.5 Summary 39
6. A Guided Tour of the GNOME 40 Desktop 41
6.1 Installing the GNOME Desktop 41
6.2 An Overview of the GNOME 40 Desktop 41
6.3 Activity Overview 42
6.4 Managing Windows 44
6.5 Using Workspaces 45
6.6 Calendar and Notifications 46
6.7 GNOME Desktop Settings 47
6.8 Beyond Basic Customization 48
6.9 Summary 48
7. An Overview of the Cockpit Web Interface 49
7.1 An Overview of Cockpit 49
7.2 Installing and Enabling Cockpit 50
7.3 Accessing Cockpit 50
7.4 Overview 51
7.5 Logs 52
7.6 Storage 53
7.7 Networking 54
7.8 Accounts 54
7.9 Services 54
7.10 Applications 55
7.11 Virtual Machines 55
7.12 Software Updates 56
7.13 Terminal 56
7.14 Connecting to Multiple Servers 57
7.15 Enabling Stored Metrics 58
7.16 Summary 59
8. Using the Bash Shell on RHEL 9 61
8.1 What is a Shell? 61
8.2 Gaining Access to the Shell 61
8.3 Entering Commands at the Prompt 62
8.4 Getting Information about a Command 62
8.5 Bash Command-line Editing 62
8.6 Working with the Shell History 63
8.7 Filename Shorthand 64
8.8 Filename and Path Completion 64
8.9 Input and Output Redirection 64
8.10 Working with Pipes in the Bash Shell 65
8.11 Configuring Aliases 65
8.12 Environment Variables 66
8.13 Writing Shell Scripts 67
8.14 Summary 68
9. Managing RHEL 9 Users and Groups 69
9.1 User Management from the Command-line 69
9.2 User Management with Cockpit 71
9.3 User Management using the Settings App 73
9.4 Summary 75
10. Understanding RHEL 9 Software Installation and Management 77
10.1 Repositories 77
10.2 The BaseOS Repository 78
10.3 The AppStream Repository 79
10.4 Summary 82
11. Managing RHEL 9 systemd Units 83
11.1 Understanding RHEL 9 systemd Targets 83
11.2 Understanding RHEL 9 systemd Services 83
11.3 RHEL 9 systemd Target Descriptions 83
11.4 Identifying and Configuring the Default Target 85
11.5 Understanding systemd Units and Unit Types 86
11.6 Dynamically Changing the Current Target 87
11.7 Enabling, Disabling, and Masking systemd Units 87
11.8 Working with systemd Units in Cockpit 89
11.9 Summary 90
12. RHEL 9 Network Management 91
12.1 An Introduction to NetworkManager 91
12.2 Installing and Enabling NetworkManager 92
12.3 Basic nmcli Commands 92
12.4 Working with Connection Profiles 96
12.5 Interactive Editing 98
12.6 Configuring NetworkManager Permissions 99
12.7 Summary 100
13. RHEL 9 Firewall Basics 101
13.1 Understanding Ports and Services 101
13.2 Securing Ports and Services 101
13.3 RHEL 9 Services and iptables Rules 102
13.4 Well-Known Ports and Services 103
13.5 Summary 106
14. RHEL 9 Firewall Configuration with firewalld 107
14.1 An Introduction to firewalld 107
14.1.1 Zones 107
14.1.2 Interfaces 109
14.1.3 Services 109
14.1.4 Ports 109
14.2 Checking firewalld Status 109
14.3 Configuring Firewall Rules with firewall-cmd 110
14.3.1 Identifying and Changing the Default Zone 110
14.3.2 Displaying Zone Information 110
14.3.3 Adding and Removing Zone Services 111
14.3.4 Working with Port-based Rules 112
14.3.5 Creating a New Zone 112
14.3.6 Changing Zone/Interface Assignments 112
14.3.7 Masquerading 112
14.3.8 Adding ICMP Rules 113
14.3.9 Implementing Port Forwarding 113
14.4 Managing firewalld from the Cockpit Interface 114
14.5 Managing firewalld using firewall-config 115
14.6 Summary 116
15. Configuring SSH Key-based Authentication on RHEL 9 117
15.1 An Overview of Secure Shell (SSH) 117
15.2 SSH Key-based Authentication 117
15.3 Setting Up Key-based Authentication 118
15.4 Installing and Starting the SSH Service 118
15.5 SSH Key-based Authentication from Linux and macOS Clients 118
15.6 Managing Multiple Keys 120
15.7 SSH Key-based Authentication from Windows Clients 121
15.8 SSH Key-based Authentication using PuTTY 123
15.9 Generating a Private Key with PuTTYgen 124
15.10 Summary 125
16. RHEL 9 Remote Desktop Access with VNC 127
16.1 Secure and Insecure Remote Desktop Access 127
16.2 Installing the GNOME Desktop Environment 127
16.3 Installing VNC on RHEL 9 129
16.4 Configuring the VNC Server 129
16.5 Connecting to a VNC Server 131
16.6 Establishing a Secure Remote Desktop Session 131
16.7 Establishing a Secure Tunnel on Windows using PuTTY 133
16.8 Shutting Down a Desktop Session 134
16.9 Troubleshooting a VNC Connection 134
16.10 Summary 135
17. Displaying RHEL 9 Applications Remotely (X11 Forwarding) 137
17.1 Requirements for Remotely Displaying RHEL 9 Applications 137
17.2 Displaying a RHEL 9 Application Remotely 138
17.3 Trusted X11 Forwarding 138
17.4 Compressed X11 Forwarding 138
17.5 Displaying Remote RHEL 9 Apps on Windows 138
17.6 Summary 141
18. Using NFS on RHEL 9 to Share Files with Remote Systems 143
18.1 Ensuring NFS Services are running on RHEL 9 143
18.2 Configuring the RHEL 9 Firewall to Allow NFS Traffic 144
18.3 Specifying the Folders to be Shared 144
18.4 Accessing Shared Folders 145
18.5 Mounting an NFS Filesystem on System Startup 145
18.6 Unmounting an NFS Mount Point 145
18.7 Accessing NFS Filesystems in Cockpit 146
18.8 Summary 147
19. Sharing Files between RHEL 9 and Windows Systems with Samba 149
19.1 Accessing Windows Resources from the GNOME Desktop 149
14.1.4 Ports 109
14.2 Checking firewalld Status 109
14.3 Configuring Firewall Rules with firewall-cmd 110
14.3.1 Identifying and Changing the Default Zone 110
14.3.2 Displaying Zone Information 110
14.3.3 Adding and Removing Zone Services 111
14.3.4 Working with Port-based Rules 112
14.3.5 Creating a New Zone 112
14.3.6 Changing Zone/Interface Assignments 112
14.3.7 Masquerading 112
14.3.8 Adding ICMP Rules 113
14.3.9 Implementing Port Forwarding 113
14.4 Managing firewalld from the Cockpit Interface 114
14.5 Managing firewalld using firewall-config 115
14.6 Summary 116
15. Configuring SSH Key-based Authentication on RHEL 9 117
15.1 An Overview of Secure Shell (SSH) 117
15.2 SSH Key-based Authentication 117
15.3 Setting Up Key-based Authentication 118
15.4 Installing and Starting the SSH Service 118
15.5 SSH Key-based Authentication from Linux and macOS Clients 118
15.6 Managing Multiple Keys 120
15.7 SSH Key-based Authentication from Windows Clients 121
15.8 SSH Key-based Authentication using PuTTY 123
15.9 Generating a Private Key with PuTTYgen 124
15.10 Summary 125
16. RHEL 9 Remote Desktop Access with VNC 127
16.1 Secure and Insecure Remote Desktop Access 127
16.2 Installing the GNOME Desktop Environment 127
16.3 Installing VNC on RHEL 9 129
16.4 Configuring the VNC Server 129
16.5 Connecting to a VNC Server 131
16.6 Establishing a Secure Remote Desktop Session 131
16.7 Establishing a Secure Tunnel on Windows using PuTTY 133
16.8 Shutting Down a Desktop Session 134
16.9 Troubleshooting a VNC Connection 134
16.10 Summary 135
17. Displaying RHEL 9 Applications Remotely (X11 Forwarding) 137
17.1 Requirements for Remotely Displaying RHEL 9 Applications 137
17.2 Displaying a RHEL 9 Application Remotely 138
17.3 Trusted X11 Forwarding 138
17.4 Compressed X11 Forwarding 138
17.5 Displaying Remote RHEL 9 Apps on Windows 138
17.6 Summary 141
18. Using NFS on RHEL 9 to Share Files with Remote Systems 143
18.1 Ensuring NFS Services are running on RHEL 9 143
18.2 Configuring the RHEL 9 Firewall to Allow NFS Traffic 144
18.3 Specifying the Folders to be Shared 144
18.4 Accessing Shared Folders 145
18.5 Mounting an NFS Filesystem on System Startup 145
18.6 Unmounting an NFS Mount Point 145
18.7 Accessing NFS Filesystems in Cockpit 146
18.8 Summary 147
19. Sharing Files between RHEL 9 and Windows Systems with Samba 149
19.1 Accessing Windows Resources from the GNOME Desktop 149
19.2 Samba and Samba Client 150
19.3 Installing Samba on RHEL 9 150
19.4 Configuring the RHEL 9 Firewall to Enable Samba 150
19.5 Configuring the smb.conf File 151
19.5.1 Configuring the [global] Section 151
19.5.2 Configuring a Shared Resource 151
19.5.3 Removing Unnecessary Shares 152
19.6 Configuring SELinux for Samba 152
19.7 Creating a Samba User 154
19.8 Testing the smb.conf File 154
19.9 Starting the Samba and NetBIOS Name Services 155
19.10 Accessing Samba Shares 156
19.11 Accessing Windows Shares from RHEL 9 158
19.12 Summary 159
20. An Overview of Virtualization Techniques 161
20.1 Guest Operating System Virtualization 161
20.2 Hypervisor Virtualization 162
20.2.1 Paravirtualization 163
20.2.2 Full Virtualization 164
20.2.3 Hardware Virtualization 164
20.3 Virtual Machine Networking 165
20.4 Summary 165
21. Installing KVM Virtualization on RHEL 9 167
21.1 An Overview of KVM 167
21.2 KVM Hardware Requirements 167
21.3 Preparing RHEL 9 for KVM Virtualization 168
21.4 Verifying the KVM Installation 168
21.5 Summary 170
22. Creating KVM Virtual Machines on RHEL 9 using Cockpit 171
22.1 Installing the Cockpit Virtual Machines Module 171
22.2 Creating a Virtual Machine in Cockpit 171
22.3 Starting the Installation 174
22.4 Working with Storage Volumes and Storage Pools 176
22.5 Summary 178
23. Creating KVM Virtual Machines on RHEL 9 using virt-manager 179
23.1 Starting the Virtual Machine Manager 179
23.2 Configuring the KVM Virtual System 180
23.3 Starting the KVM Virtual Machine 184
23.4 Summary 185
24. Creating KVM Virtual Machines with virt-install and virsh 187
24.1 Running virt-install to build a KVM Guest System 187
24.2 An Example RHEL 9 virt-install Command 187
24.3 Starting and Stopping a Virtual Machine from the Command-Line 188
24.4 Creating a Virtual Machine from a Configuration File 189
24.5 Summary 189
25. Creating a RHEL 9 KVM Networked Bridge Interface 191
25.1 Getting the Current Network Manager Settings 191
25.2 Creating a Network Manager Bridge from the Command-Line 193
25.3 Declaring the KVM Bridged Network 194
25.4 Using a Bridge Network in a Virtual Machine 195
25.5 Creating a Bridge Network using nm-connection-editor 197
25.6 Summary 200
26. Managing KVM using the virsh Command-Line Tool 201
26.1 The virsh Shell and Command-Line 201
26.2 Listing Guest System Status 202
26.3 Starting a Guest System 203
26.4 Shutting Down a Guest System 203
26.5 Suspending and Resuming a Guest System 203
26.6 Saving and Restoring Guest Systems 203
26.7 Rebooting a Guest System 204
26.8 Configuring the Memory Assigned to a Guest OS 204
26.9 Summary 204
27. An Introduction to Linux Containers 205
27.1 Linux Containers and Kernel Sharing 205
27.2 Container Uses and Advantages 206
27.3 RHEL 9 Container Tools 207
27.4 Container Catalogs, Repositories, and Registries 207
27.5 Container Networking 208
27.6 Summary 208
28. Working with Containers on RHEL 9 209
28.1 Installing the Container Tools 209
28.2 Logging in to the Red Hat Container Registry 209
28.3 Pulling a Container Image 209
28.4 Running the Image in a Container 211
28.5 Managing a Container 213
28.6 Saving a Container to an Image 213
28.7 Removing an Image from Local Storage 214
28.8 Removing Containers 214
28.9 Building a Container with Buildah 214
28.10 Building a Container from Scratch 214
28.11 Container Bridge Networking 215
28.12 Managing Containers in Cockpit 218
28.13 Summary 221
29. Setting Up a RHEL 9 Web Server 223
29.1 Requirements for Configuring a RHEL 9 Web Server 223
29.2 Installing the Apache Web Server Packages 223
29.3 Configuring the Firewall 224
29.4 Port Forwarding 224
29.5 Starting the Apache Web Server 224
29.6 Testing the Web Server 224
29.7 Configuring the Apache Web Server for Your Domain 225
29.8 The Basics of a Secure Website 226
29.9 Configuring Apache for HTTPS 227
29.10 Obtaining an SSL Certificate 227
29.11 Summary 229
30. Configuring a RHEL 9 Postfix Email Server 231
30.1 The Structure of the Email System 231
30.1.1 Mail User Agent 231
30.1.2 Mail Transfer Agent 231
30.1.3 Mail Delivery Agent 231
30.1.4 SMTP 232
30.1.5 SMTP Relay 232
30.2 Configuring a RHEL 9 Email Server 232
30.3 Postfix Pre-Installation Steps 232
30.4 Firewall/Router Configuration 233
30.5 Installing Postfix on RHEL 9 233
30.6 Configuring Postfix 233
30.7 Configuring DNS MX Records 235
30.8 Starting Postfix on a RHEL 9 System 235
30.9 Testing Postfix 235
30.10 Sending Mail via an SMTP Relay Server 236
30.11 Summary 237
31. Adding a New Disk Drive to a RHEL 9 System 239
31.1 Mounted File Systems or Logical Volumes 239
31.2 Finding the New Hard Drive 239
31.3 Creating Linux Partitions 240
31.4 Creating a File System on a RHEL 9 Disk Partition 241
31.5 An Overview of Journaled File Systems 242
31.6 Mounting a File System 242
31.7 Configuring RHEL 9 to Mount a File System Automatically 243
31.8 Adding a Disk Using Cockpit 243
31.9 Summary 245
32. Adding a New Disk to a RHEL 9 Volume Group and Logical Volume 247
32.1 An Overview of Logical Volume Management (LVM) 247
32.1.1 Volume Group (VG) 247
32.1.2 Physical Volume (PV) 247
32.1.3 Logical Volume (LV) 248
32.1.4 Physical Extent (PE) 248
32.1.5 Logical Extent (LE) 248
32.2 Getting Information about Logical Volumes 248
32.3 Adding Additional Space to a Volume Group from the Command-Line 251
32.4 Adding Additional Space to a Volume Group Using Cockpit 253
32.5 Summary 255
33. Adding and Managing RHEL 9 Swap Space 257
33.1 What is Swap Space? 257
33.2 Recommended Swap Space for RHEL 9 257
33.3 Identifying Current Swap Space Usage 257
33.4 Adding a Swap File to a RHEL 9 System 258
33.5 Adding Swap as a Partition 259
33.6 Adding Space to a RHEL 9 LVM Swap Volume 259
33.7 Adding Swap Space to the Volume Group 260
33.8 Summary 262
34. RHEL 9 System and Process Monitoring 263
34.1 Managing Processes 263
34.2 Real-time System Monitoring with top 267
34.3 Command-Line Disk and Swap Space Monitoring 268
34.4 Summary 269
Index 271
