18. Configuring SSH Key-based Authentication on Ubuntu

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Ubuntu 20.04 Essentials

By : Neil Smyth

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Ubuntu 20.04 Essentials

By: Neil Smyth

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Overview of this book

Ubuntu is undeniably one of the most highly regarded and widely used Debian-based Linux distributions available today. Thanks to its ease of use and reliability, Ubuntu has a loyal following of Linux users and an active community of developers. Ubuntu 20.04 Essentials is designed to take you through the installation, use, and administration of the Ubuntu 20.04 distribution in detail. 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. Additional installation topics such as dual booting with Microsoft Windows are also covered along with crucial security topics such as configuring a firewall and user and group administration. For the experienced user, the book delves into topics such as remote desktop access, the Cockpit web interface, logical volume management (LVM), disk partitioning, and swap management. Further, it also explores KVM virtualization, Secure Shell (SSH), Linux containers, and file sharing using both Samba and NFS to provide a thorough overview of this enterprise-class operating system.

1. Introduction

1.1 Superuser Conventions

1.2 Opening a Terminal Window

1.3 Editing Files

1.4 Feedback

1.5 Errata

Free Chapter

2. A Brief History of Linux

2.1 What exactly is Linux?

2.2 UNIX Origins

2.3 Who Created Linux?

2.4 The History of Ubuntu

2.5 What does the word “Ubuntu” Mean?

2.6 Summary

3. Installing Ubuntu on a Clean Disk Drive

3.1 Ubuntu Installation Options

3.2 Server vs. Desktop Editions

3.3 Obtaining the Ubuntu Installation Media

3.4 Writing the ISO Installation Image to a USB Drive

3.5 Booting from the Ubuntu USB Image

3.6 Installing Ubuntu

3.7 Accessing the Ubuntu Desktop

3.8 Installing Updates

3.9 Displaying Boot Messages

3.10 Summary

4. Installing Ubuntu with the Network Installer

4.1 Network Installer Advantages

4.2 Obtaining the Network Installer Image

4.3 Booting from the Installer Image

4.4 Performing the Installation

4.5 Disk Partitioning

4.6 Software Collection Selection

4.7 Installing Software Collections After System Setup

4.8 Summary

5. Dual Booting Ubuntu with Windows

5.1 Beginning the Ubuntu Installation

5.2 Booting Ubuntu for the First Time

5.3 Changing the Default Boot Option

5.4 Accessing the Windows Partition from the Command-line

5.5 Accessing the Windows Partition from the Desktop

5.6 Summary

6. Allocating Windows Disk Partitions to Ubuntu

6.1 Unmounting the Windows Partition

6.2 Deleting the Windows Partitions from the Disk

6.3 Formatting the Unallocated Disk Partition

6.4 Mounting the New Partition

6.5 Editing the Boot Menu

6.6 Using the GNOME Disks Utility

6.7 Summary

7. A Guided Tour of the GNOME 3 Desktop

7.1 Installing the GNOME Desktop

7.2 An Overview of the GNOME 3 Desktop

7.3 Launching Activities

7.4 Managing Windows

7.5 Using Workspaces

7.6 Calendar and Notifications

7.7 Desktop Settings

7.8 Customizing the Dash

7.9 Switching to Dark Mode

7.10 Installing Ubuntu Software

7.11 Beyond Basic Customization

7.12 Summary

8. An Overview of the Ubuntu Cockpit Web Interface

8.1 An Overview of Cockpit

8.2 Installing and Enabling Cockpit

8.3 Accessing Cockpit

8.4 Overview

8.5 Logs

8.6 Storage

8.7 Networking

8.8 Accounts

8.9 Services

8.10 Applications

8.11 Virtual Machines

8.12 Software Updates

8.13 Terminal

8.14 Connecting to Multiple Servers

8.15 Summary

9. Using the Bash Shell on Ubuntu

9.1 What is a Shell?

9.2 Gaining Access to the Shell

9.3 Entering Commands at the Prompt

9.4 Getting Information about a Command

9.5 Bash Command-line Editing

9.6 Working with the Shell History

9.7 Filename Shorthand

9.8 Filename and Path Completion

9.9 Input and Output Redirection

9.10 Working with Pipes in the Bash Shell

9.11 Configuring Aliases

9.12 Environment Variables

9.13 Writing Shell Scripts

9.14 Summary

10. Managing Ubuntu Users and Groups

10.1 User Management from the Command-line

10.2 User Management with Cockpit

10.3 User Management using the Settings App

10.4 Summary

11. Managing Ubuntu systemd Units

11.1 Understanding Ubuntu systemd Targets

11.2 Understanding Ubuntu systemd Services

11.3 Ubuntu systemd Target Descriptions

11.4 Identifying and Configuring the Default Target

11.5 Understanding systemd Units and Unit Types

11.6 Dynamically Changing the Current Target

11.7 Enabling, Disabling and Masking systemd Units

11.8 Working with systemd Units in Cockpit

11.9 Summary

12. Ubuntu Software Package Management and Updates

12.1 Repositories

12.2 Managing Repositories with Software & Updates

12.3 Managing Packages with APT

12.4 Performing Updates

12.5 Enabling Automatic Updates

12.6 Enabling Livepatch

12.7 Summary

13. Ubuntu Snap Package Management

13.1 Managing Software with Snap

13.2 Basic Snap Commands

13.3 Working with Snap Channels

13.4 Snap Refresh Schedule

13.5 Snap Services

13.6 Summary

14. Ubuntu Network Management

14.1 An Introduction to NetworkManager

14.2 Installing and Enabling NetworkManager

14.3 Basic nmcli Commands

14.4 Working with Connection Profiles

14.5 Interactive Editing

14.6 Configuring NetworkManager Permissions

14.7 Summary

15. Ubuntu Firewall Basics

15.1 Understanding Ports and Services

15.2 Securing Ports and Services

15.3 Ubuntu Services and iptables Rules

15.4 Well Known Ports and Services

15.5 Summary

16. Using gufw and ufw to Configure an Ubuntu Firewall

16.1 An Overview of gufw and ufw

16.2 Installing gufw on Ubuntu

16.3 Running and Enabling gufw

16.4 Creating a New Profile

16.5 Adding Preconfigured Firewall Rules

16.6 Adding Simple Firewall Rules

16.7 Adding Advanced Rules

16.8 Configuring the Firewall from the Command Line using ufw

16.9 Summary

17. Basic Ubuntu Firewall Configuration with firewalld

17.1 An Introduction to firewalld

17.2 Checking firewalld Status

17.3 Configuring Firewall Rules with firewall-cmd

17.4 Managing firewalld using firewall-config

17.5 Summary

18. Configuring SSH Key-based Authentication on Ubuntu

18.1 An Overview of Secure Shell (SSH)

18.2 SSH Key-based Authentication

18.3 Setting Up Key-based Authentication

18.4 Installing and Starting the SSH Service

18.5 SSH Key-based Authentication from Linux and macOS Clients

18.6 Managing Multiple Keys

18.7 SSH Key-based Authentication from Windows 10 Clients

18.8 SSH Key-based Authentication using PuTTY

18.9 Generating a Private Key with PuTTYgen

18.10 Installing the Public Key for a Google Cloud Instance

18.11 Summary

19. Ubuntu Remote Desktop Access with Vino

19.1 Remote Desktop Access Types

19.2 Secure and Insecure Remote Desktop Access

19.3 Enabling Remote Desktop Access on Ubuntu

19.4 Connecting to the Shared Desktop

19.5 Connecting from Non-Linux Clients

19.6 Establishing a Secure Remote Desktop Session

19.7 Establishing a Secure Tunnel on Windows using PuTTY

19.8 Summary

20. Ubuntu Remote Desktop Access with VNC

20.1 Installing the GNOME Desktop Environment

20.2 Installing VNC on Ubuntu

20.3 Configuring the VNC Server

20.4 Starting the VNC Server

20.5 Connecting to a VNC Server

20.6 Summary

21. Displaying Ubuntu Applications Remotely (X11 Forwarding)

21.1 Requirements for Remotely Displaying Ubuntu Applications

21.2 Remotely Displaying an Ubuntu Application

21.3 Trusted X11 Forwarding

21.4 Compressed X11 Forwarding

21.5 Displaying Remote Ubuntu Apps on Windows

21.6 Summary

22. Using NFS to Share Ubuntu Files with Remote Systems

22.1 Ensuring NFS Services are running on Ubuntu

22.2 Configuring the Ubuntu Firewall to Allow NFS Traffic

22.3 Specifying the Folders to be Shared

22.4 Accessing Shared Ubuntu Folders

22.5 Mounting an NFS Filesystem on System Startup

22.6 Unmounting an NFS Mount Point

22.7 Accessing NFS Filesystems in Cockpit

22.8 Summary

23. Sharing Files between Ubuntu and Windows Systems with Samba

23.1 Accessing Windows Resources from the GNOME Desktop

23.2 Samba and Samba Client

23.3 Installing Samba on an Ubuntu System

23.4 Configuring the Ubuntu Firewall to Enable Samba

23.5 Configuring the smb.conf File

23.6 Creating a Samba User

23.7 Testing the smb.conf File

23.8 Starting the Samba and NetBIOS Name Services

23.9 Accessing Samba Shares

23.10 Accessing Windows Shares from Ubuntu

23.11 Summary

24. An Overview of Virtualization Techniques

24.1 Guest Operating System Virtualization

24.2 Hypervisor Virtualization

24.3 Virtual Machine Networking

24.4 Summary

25. Installing KVM Virtualization on Ubuntu

25.1 An Overview of KVM

25.2 KVM Hardware Requirements

25.3 Preparing Ubuntu for KVM Virtualization

25.4 Verifying the KVM Installation

25.5 Summary

26. Creating KVM Virtual Machines using Cockpit and virt-manager

26.1 Installing the Cockpit Virtual Machines Module

26.2 Creating a Virtual Machine in Cockpit

26.3 Starting the Installation

26.4 Working with Storage Volumes and Storage Pools

26.5 Creating a Virtual Machine using virt-manager

26.6 Starting the Virtual Machine Manager

26.7 Configuring the KVM Virtual System

26.8 Starting the KVM Virtual Machine

26.9 Summary

27. Creating KVM Virtual Machines with virt-install and virsh

27.1 Running virt-install to build a KVM Guest System

27.2 An Example Ubuntu virt-install Command

27.3 Starting and Stopping a Virtual Machine from the Command-Line

27.4 Creating a Virtual Machine from a Configuration File

27.5 Summary

28. Creating an Ubuntu KVM Networked Bridge Interface

28.1 Identifying the Network Management System

28.2 Getting the Netplan Network Settings

28.3 Creating a Netplan Network Bridge

28.4 Getting the Current Network Manager Settings

28.5 Creating a Network Manager Bridge from the Command-Line

28.6 Declaring the KVM Bridged Network

28.7 Using a Bridge Network in a Virtual Machine

28.8 Creating a Bridge Network using nm-connection-editor

28.9 Summary

29. Managing KVM using the virsh Command-Line Tool

29.1 The virsh Shell and Command-Line

29.2 Listing Guest System Status

29.3 Starting a Guest System

29.4 Shutting Down a Guest System

29.5 Suspending and Resuming a Guest System

29.6 Saving and Restoring Guest Systems

29.7 Rebooting a Guest System

29.8 Configuring the Memory Assigned to a Guest OS

29.9 Summary

30. An Introduction to Linux Containers

30.1 Linux Containers and Kernel Sharing

30.2 Container Uses and Advantages

30.3 Ubuntu Container Tools

30.4 The Docker Registry

30.5 Container Networking

30.6 Summary

31. Working with Containers on Ubuntu

31.1 Installing the Container Tools

31.2 Pulling a Container Image

31.3 Running the Image in a Container

31.4 Managing a Container

31.5 Saving a Container to an Image

31.6 Removing an Image from Local Storage

31.7 Removing Containers

31.8 Building a Container with Buildah

31.9 Summary

32. Setting Up an Ubuntu Web Server

32.1 Requirements for Configuring an Ubuntu Web Server

32.2 Installing the Apache Web Server Packages

32.3 Configuring the Firewall

32.4 Port Forwarding

32.5 Starting the Apache Web Server

32.6 Testing the Web Server

32.7 Configuring the Apache Web Server for Your Domain

32.8 The Basics of a Secure Web Site

32.9 Configuring Apache for HTTPS

32.10 Obtaining an SSL Certificate

32.11 Summary

33. Configuring an Ubuntu Postfix Email Server

33.1 The structure of the Email System

33.2 Configuring an Ubuntu Email Server

33.3 Postfix Pre-Installation Steps

33.4 Firewall/Router Configuration

33.5 Installing Postfix on Ubuntu

33.6 Configuring Postfix

33.7 Configuring DNS MX Records

33.8 Starting Postfix on an Ubuntu System

33.9 Testing Postfix

33.10 Sending Mail via an SMTP Relay Server

33.11 Summary

34. Adding a New Disk Drive to an Ubuntu System

34.1 Mounted File Systems or Logical Volumes

34.2 Finding the New Hard Drive

34.3 Creating Linux Partitions

34.4 Creating a File System on a Disk Partition

34.5 An Overview of Journaled File Systems

34.6 Mounting a File System

34.7 Configuring Ubuntu to Automatically Mount a File System

34.8 Adding a Disk Using Cockpit

34.9 Summary

35. Adding a New Disk to an Ubuntu Volume Group and Logical Volume

35.1 An Overview of Logical Volume Management (LVM)

35.2 Getting Information about Logical Volumes

35.3 Adding Additional Space to a Volume Group from the Command-Line

35.4 Summary

36. Adding and Managing Ubuntu Swap Space

36.1 What is Swap Space?

36.2 Recommended Swap Space for Ubuntu

36.3 Identifying Current Swap Space Usage

36.4 Adding a Swap File to an Ubuntu System

36.5 Adding Swap as a Partition

36.6 Adding Space to an Ubuntu LVM Swap Volume

36.7 Adding Swap Space to the Volume Group

36.8 Summary

37. Ubuntu System and Process Monitoring

37.1 Managing Processes

37.2 Real-time System Monitoring with htop

37.3 Command-Line Disk and Swap Space Monitoring

37.4 Summary

Index

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Ubuntu 20.04 Essentials

By : Neil Smyth

Ubuntu 20.04 Essentials

By: Neil Smyth

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