book

Beginning Linux SysAdmin: Getting Started with Linux System Administration

Name: Beginning Linux SysAdmin: Getting Started with Linux System Administration
Author: Neville Asiago Ondara
ISBN: 9798868821639

by Neville Asiago Ondara

January 2026

Beginner

305 pages

4h 4m

English

Apress

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Beginning Linux SysAdmin
Introduction
What This Book CoversWho This Book Is ForBook StructureHow to Use This BookA Note from the Author
Acknowledgments
Table of Contents
About the Author
About the Technical Reviewer
1. Introduction to Linux Administration
Choosing and Setting Up Linux DistributionsWhat Is a Linux Distribution?Major Types of Linux DistributionsDebian-Based DistributionsRed Hat–Based DistributionsArch-Based DistributionsSUSE-Based DistributionsChoosing the Right Linux DistributionDesktop vs. Server DistributionsDesktop DistributionsServer DistributionsInstalling and Setting Up LinuxSelecting How to Install LinuxDownloading the Linux ISO FileCreating a Bootable USB DriveFor Windows: Use EtcherFor Windows: Use RufusLinux: Using lsblk and ddmacOS: Using diskutil and ddBooting from USBInstalling LinuxDistribution DifferencesInstalling with a GUI Installer (Ubuntu Desktop)Post-installation SetupCommand-Line EssentialsWhat Is the Terminal?Basic Structure of a CommandMust-Know Linux CommandsGetting HelpReal-World Scenario: Managing a Server via SSHKey Takeaways
2. Managing User Accounts
What Is sudo?Introduction to Linux UsersCreating New UsersCreating a New User with useraddCreating a User with adduserChanging a UsernameChanging a User’s Home DirectoryDeleting UsersManaging GroupsCreating a GroupAdding Users to a GroupChecking Group MembershipsUnderstanding File PermissionsChanging Permissions with chmodChanging Ownership with chownEnforcing Strong Password PoliciesReal-World Scenario: New Employee OnboardingKey Takeaways
3. Filesystem Management
Understanding the Linux Filesystem HierarchyChecking Disk UsageDisk PartitioningPartitioning a Disk with fdiskCreating a Filesystem Partition on /dev/sdbFormatting PartitionsMounting and Unmounting FilesystemsManually Mount a DriveUnmount the DriveMaking Mounts Permanent with /etc/fstabCreating and Managing Swap SpaceCheck Current Swap SpaceCreating a Swap FileSwap and HibernationMonitoring Disk HealthCheck Disk IO UsageSMART Disk Health CheckKey Takeaways
4. Basic System Configuration
Why System Configuration MattersManaging System Services with systemdUnderstanding systemd UnitsCommon Unit TypesExample ServicesViewing Service StatusStarting the SSH Service (If It Didn’t Auto-start)Enabling SSH on BootVerifying SSH ConnectivityList All ServicesCheck Failed ServicesProcess ManagementViewing Running Processes with ps auxReal-Time Monitoring with topEnhanced Interactive View with htopManaging ProcessesKilling a ProcessSending SignalsAdjusting Process PriorityWhat Is “nice”?Job Control in the ShellBasic Networking SetupChecking Network InterfacesSetting a Static IP Address (Ubuntu Netplan)Validating and Applying Netplan SafelyConfirming the IP AddressTesting Network Connectivity to the Local GatewayTesting Connectivity to an External DomainChecking DNS ResolutionSystem Time and Time Zone ConfigurationSetting the Time ZoneSet Your Time ZoneSynchronizing Time with NTP or ChronyInstall Chrony (Recommended)apt vs. apt-get in ScriptsCheck Sync StatusHardware Clock vs. System ClockLocale and Language SettingsViewing the Current LocaleSetting the Default LanguageAutomating Configuration with ScriptsNotes on AutomationNon-interactive UFW (Uncomplicated Firewall) SetupConclusion

5. Package Management
Understanding Package ManagementPlaceholder and Example PolicyUniversal Package Management WrappersAPT/dpkg (Debian, Ubuntu, Linux Mint)APT Command Examples (Ubuntu 25.04)Update Package ListsInstall PackagesUpgrade All PackagesSearch for a PackageRemove and PurgeClean Up PackagesFix Broken InstallsDNF/YUM/RPM (Fedora, RHEL, CentOS, AlmaLinux, Rocky Linux)Update RepositoriesInstall PackagesUpdate the SystemRemove PackagesClean MetadataAuto-remove Unused DependenciesSearch for PackagesAdd and Manage Third-Party Repositories (MySQL Example)Disable and Enable ReposPacman (Arch-Based Systems: Arch, Manjaro)Sync and UpdateInstall PackagesRemove PackagesForce Remove Without Dependency ChecksClean Package CacheSearch for PackagesNix and Guix: Declarative, Atomic Package ManagementNixInstall PackagesList Installed PackagesUpgrade PackagesRevert to Previous GenerationGuix (GNU Guix System)Common Guix CommandsInstall PackagesList Installed PackagesGarbage-Collect Unused Store ItemsRoll Back the Last TransactionSnap and Flatpak: Containerized Desktop PackagingSnapInstall PackagesList PackagesRemove PackagesFlatpakInstall PackagesList PackagesUninstall PackagesSlackware-Based Systems (pkgtool/slackpkg, .tgz/.txz)Important ConsiderationsExample: Manually Installing a DependencyExtending Slackware with Community ToolsVoid Linux (XBPS, .xbps)Solus (eopkg, .eopkg)CRUX (pkgmk, pkgadd, .tar.gz)GUI and Web-Based Tools for Package ManagementSynaptic Package Manager (Debian, Ubuntu, Linux Mint)Key FeaturesExample: Locking a Package Version Using SynapticLimitationsRecommended UsagePamac (Manjaro, Arch Linux)Key FeaturesCockpit’s PackageKit Plugin (Fedora, RHEL, AlmaLinux, Rocky Linux)Key FeaturesInstallation and Setup (Fedora/RHEL-Based Systems)Install Cockpit and the PackageKit PluginEnable and Start the Cockpit Web ServiceFirewall and SELinux ConsiderationsWhen to Use Cockpit’s PackageKit PluginNixUI/Guix Web Interfaces (NixOS, GNU Guix System)Key FeaturesInstallation InstructionsNixUI (for NixOS or Nix on Other Distros)Guix Web Interface (guix-web)Security and AuditingClarifying Edge Cases in Package ManagementConflicts Between Snap, Flatpak, and Native Packages (APT/DNF/RPM)ExampleFlatpak Permissions and Sandboxing LimitationsCommon LimitationsManaging Flatpak PermissionsFlatseal (GUI Tool)Terminal (Manual Overrides)Safer, Granular AlternativesGood PracticesManaging Dual Systems (e.g., Flatpak + RPM on Fedora)Conclusion
6. Introduction to Shell Scripting
What Is Shell Scripting?Why Shell Scripting Matters in Linux System AdministrationUnderstanding the ShellBash and Other ShellsThe Shell as a Command InterpreterShell Scripting BasicsCreating Your First Shell ScriptFile Permissions and the Shebang (#!)Running ScriptsVariablesDeclaring VariablesEnvironment VariablesQuoting: Single vs. DoubleUser Input and OutputEcho and PrintCommand SubstitutionConditional Statementsif, else, and eliftest and [ ] ConditionsCase StatementsLoopsfor Loopswhile Loopsuntil LoopsFunctions in Shell ScriptsReturning ValuesError Handling and DebuggingExit StatusDebugging with setLogging ErrorsAutomating Tasks with Shell ScriptsAutomated Full System Backup with Logging and CompressionObjectiveAutomated Security Patch Installation with ReportingObjectiveServer Resource Monitoring and Alert SystemObjectiveAutomated Log Analyzer and Report GeneratorObjectiveAutomated User Account Creation and ConfigurationObjectiveScheduling Scripts with cronHow cron WorksHow It Works InternallyEditing Your CrontabCommon Examples of cron JobsAdvanced Scheduling PatternsMultiple ValuesInterval RunsRun the Script at RebootPermissions and Environment in cronSolutionsLogging and OutputExample with LoggingViewing Crontab EntriesRemove Your CrontabEdit the System-Wide CrontabViewing cron Job LogsTraditional syslog (Some Distributions)Using journalctl (on systemd-Based Systems)Testing Your cron Jobscron Troubleshooting TipsReal-World Use Case: Scheduled Backup with cronTaskSet Up the Cron JobBest PracticesConclusion
7. System Monitoring and Performance
Tools for Monitoring System Performancetop, htop, and Other Monitoring ToolstophtopInstallationDebian/UbuntuRHEL/CentOS/Fedoravmstat: Virtual Memory StatisticsInstallationDebian/UbuntuRHEL/CentOS/FedoraUsageOptional EnhancementsAdd pidstat for Per-Process Statisticsiostat: Input/Output StatisticsInstallationDebian/UbuntuRHEL/CentOS/FedoraUsageKey Metricsfree: Memory Usage SnapshotInstallationDebian/UbuntuRHEL/CentOSUsagedstat: Versatile All-in-One Resource MonitorInstallationDebian/UbuntuRHEL/CentOSBasic UsageWhen to Use Which ToolChecking Memory and Disk UsageMemory UsageUsing vmstatDisk UsageUsing du: Disk Usage per DirectoryAnalyzing System Resource ConsumptionFind High-CPU or High-Memory ProcessesUsing top or htopUsing psMonitor Disk IO per Process with iotopTroubleshooting and Prerequisites for iotop and Related ToolsManaging System LogsOverview of Log Files (/var/log)/var/log/syslog: System Messages (Debian/Ubuntu)/var/log/messages: System Messages (RHEL/CentOS)/var/log/kern.log: Kernel Logs/var/log/dmesg: Boot and Hardware Logs/var/log/apt/: Package Management LogsTips for Viewing LogsUsing journalctl (for systemd-Based Systems)View All LogsLogs from a Specific ServiceLogs from the Current BootReal-Time Logs (like tail -f)Show Errors and ExplanationsRotating and Cleaning LogsLog Rotation with logrotateWhat It DoesDry Run (Debug Mode)Manually Rotate LogsTo See What logrotate Is Doing, Add -v (Verbose) or -d (Debug)Identifying and Resolving Performance BottlenecksIdentifying High-Resource ProcessesCPU/Memory Hogs with htopDisk IO Hogs with iotopNetwork UsagePerformance Optimization TipsDisable Unused ServicesClean Temporary FilesClean ManuallyWarning: Manual Deletion Can Be RiskyIf You Must Manually Clean (Proceed with Extreme Caution)Safer Alternatives for Cleaning Temporary FilesOn Debian/UbuntuOn RHEL/CentOS/Fedora/AlmaLinux/RockyAdjust SwappinessUse Lighter Desktop EnvironmentsTuning System ParametersIncrease File DescriptorsFor systemd Services: Use LimitNOFILE=Create a Drop-In OverrideImportance of Increasing the File Descriptor Limit (ulimit -n)TCP Network Performance TweaksReduce Stale TCP Connections and Improve Backlog HandlingCaution: About net.ipv4.tcp_tw_reuseMake Settings PersistentImportance of TCP Network Performance TweaksLong-Term Monitoring ToolsNetdata (Dashboard via the Web)Access the Web DashboardOpen in a BrowserWhat You’ll SeeClarifications and Troubleshootingiostat and sysstat: Immediate vs. Historical Usagenetstat vs. ss: Which to Use?Memory Metrics: “Used” vs. “Available”iotop Prerequisites and TroubleshootingLinux Observability and Monitoring: Command Cheat SheetConclusion
8. Introduction to Security
Basic Security ConceptsConfidentialityIntegrityAvailabilityKey DefinitionsSecurity PrinciplesLeast PrivilegeDefense in DepthZero TrustCommon Linux Security ToolsPopular ToolsConfiguring FirewallsIntroduction to iptables and firewalldFirewall Setup: Before You Start (iptables/nftables/firewalld)Packet Filtering with iptables, nftables, and firewalldiptables (Legacy Firewall Tool)Basic iptables Examplenftables (Modern Replacement for iptables)firewalld (Front End for nftables or iptables)Setting Up Basic Firewall Rules with firewalldAllowing and Blocking PortsUser Authentication and AuthorizationUnderstanding Authentication MethodsBefore You Start: SSH HardeningPassword-Based Authentication (Default Method)ProsConsHow to Use It (and Secure It)Best Practices for Password-Based LoginSetting Up SSH Key AuthenticationWhy Use SSH Keys Instead of Passwords?Step-by-Step Guide: SSH Key AuthenticationTest SSH Login Without a PasswordOptional: Disable Password Authentication on the ServerSet Up Two-Factor Authentication (2FA)Before You Start: Enabling SSH 2FAWhy Use 2FA?Step-by-Step SetupInstall the Google Authenticator PAM ModuleRun on Each User AccountEdit PAM ConfigurationEdit SSH ConfigurationTest SSH LoginFail2Ban: Automatically Block Brute-Force AttacksWhat Is Fail2Ban?Step-by-Step SetupInstall Fail2BanCreate the Config FileStart and Enable Fail2BanCheck StatusUnban an IPMonitor Logins with auditd (Audit Daemon)Why Use auditd?Step-by-Step SetupAudit Login EventsAudit SSH Config File ChangesView Audit LogOptional: Restrict SSH Access by IP AddressRestrict SSH Access Using UFWDeny All Other SSHCheck StatusUnderstanding AppArmor and SELinux (MAC Systems)What Is MAC (Mandatory Access Control)?MAC vs. DACSELinux: Security-Enhanced LinuxWhat Is SELinux?SELinux ModesHow SELinux Works: ConceptsBasic SELinux CommandsFix the 403 Error with SELinuxView SELinux LogsInstall GUI Tools (Optional for Testing)AppArmor: Application ArmorWhat Is AppArmor?Check AppArmor StatusHow AppArmor WorksEnable/Disable ProfilesPut into Complain ModeEdit AppArmor ProfilesProfile LocationView AppArmor LogsWhich One Should You Use?Real-World Scenario: Hardening a Web Serverchkrootkit/rkhunter: Rootkit Detection ToolsHow to Detect Rootkits on LinuxchkrootkitWhat Is chkrootkit?InstallationOn Ubuntu/DebianOn RHEL/CentOSrkhunter (Rootkit Hunter)What Is rkhunter?InstallationOn Ubuntu/DebianOn RHEL/CentOSUpdate Before ScanningRun a Full ScanOptional: Run Daily with cronBest Practices for Rootkit DetectionWhat to Do If You Suspect a Rootkit?Conclusion
9. Networking and Remote Access
Hostname and DNS ConfigurationSetting the HostnameChanging the HostnameEditing /etc/hosts and /etc/resolv.conf/etc/hosts: Local Name Mapping/etc/resolv.conf: DNS Server ConfigurationEditing /etc/resolv.confImportant Notessystemd-resolved vs. resolvconfViewing DNS Configuration with resolvectlWhat This MeansresolvconfHow DNS Lookups Work on LinuxCheck /etc/hostsCheck nsswitch.confUse the DNS ServerKey TakeawaysStatic vs. Dynamic IP AddressingDynamic IP AddressingStatic IP AddressingEditing Network Configuration FilesDebian/UbuntuOld Method: /etc/network/interfacesConfiguring DNS with Netplan (/etc/netplan/*.yaml)Apply the ConfigurationRed Hat/CentOS/Fedora NetworkingUsing nmcli (NetworkManager Command-Line Tool)Using Legacy Network Scripts (Deprecated)Package Management NoteTroubleshooting Network InterfacesCheck Interface and IP AddressTest Network ConnectivityRestart Interface or NetworkManagerView Logs from NetworkManagerSetting Up SSH for Remote AccessInstalling SSHDebian/UbuntuRed Hat/CentOS/FedoraCheck SSH Service StatusConfigure SSH SettingsManaging SSH Access Through FirewallsDebian/Ubuntu: UFW (Uncomplicated Firewall)Red Hat/CentOS/Fedora: firewalld (firewall-cmd)SSH Connection and Key AuthenticationConnect via SSH (Password Login)Set Up SSH Key AuthenticationManual Alternative to ssh-copy-idTest the ConnectionRemote Access Logging and MonitoringUnderstanding Linux Log Files for SSHUsing who, w, and lastwho: See Currently Logged-In Usersw: See Who Is Logged In and What They’re Doinglast: Show Login HistoryViewing SSH Service Logs with journalctlDetecting Failed Login AttemptsProactive Monitoring ToolsTracking Logins with the Linux Audit Daemon (auditd)Install and Start auditdUbuntu/DebianRed Hat/CentOS/FedoraView Login EventsNote on ConfigurationRemote Desktop and GUI AccessWhen Do You Need Remote GUI Access?Option 1: Using VNC (Virtual Network Computing)Setting Up a VNC Server on the Remote HostSecure VNC with SSH TunnelingUsing xRDP (Windows-Compatible Remote Desktop)Install xRDP on LinuxConnect from Windows or RemminaRunning GUI Apps over SSH (SSH Tunneling)RequirementsServer Side: Enable X11 Forwarding in SSHClient Side: Connect with X11 ForwardingImportant: X11 Forwarding and Wayland LimitationsCommon Issues Under WaylandWorkarounds and SolutionsSecurity and Performance TipsVirtual Private Networks (VPNs) and Remote ConnectionsLog In and Download Config FilesSetting Up OpenVPN (Client)Install OpenVPNOn Debian/UbuntuOn RHEL/CentOS/FedoraTest the VPN ManuallyStore and Configure OpenVPN for systemdAdd Login Credentials (Optional)Start and Enable the OpenVPN ServiceSystemd Service Name May VarySetting Up WireGuard on UbuntuOption 1: Using a Provider-Generated WireGuard ConfigInstall WireGuardPlace the Config FileSecure the Config FileStart the VPNEnable WireGuard at BootCheck VPN StatusImportant NotesOption 2: Manual Setup with Your Own KeysGenerate Key PairCreate the WireGuard ConfigTroubleshooting TipsSecure Remote File Transfer Using SCP and SFTPSCP (Secure Copy)SFTP (SSH File Transfer Protocol)Tips for Secure File TransferConclusion
10. Backup and Disaster Recovery
Backup StrategiesThe Importance of Regular BackupsBefore You Start Backing Up, Follow This ChecklistBackup Tools: rsync, tar, and Othersrsync: Remote SyncHow Does rsync Work?Basic Example: Local BackupExample with Remote BackupExample of Incremental Backup with rsyncImportant Notes About --link-destExample Directory LayoutExample CommandtarHow Does tar Work?Basic Example: Creating a Compressed BackupExample of Extracting Files from a BackupExample of Incremental Backup with tardd: Disk DuplicateHow Does dd Work?Basic Example: Creating a Disk ImageRestoring from a dd BackupStep 1: Identify the Correct Target DeviceStep 2: Restore the ImageChecking for status=progress SupportCloud Backup OptionsAmazon S3Why Use S3 for Backups?Install the AWS CLI on LinuxAbout AWS CLI VersionsMethod 1: Recommended—Official AWS CLI v2 InstallerMethod 2: Optional—Install via the OS Package Manager (May Install v1)Configure AWS CLIWhere to Get These?Create an S3 BucketSpecify a Region (Recommended)Bucket Naming Rules (Strict)Prepare the Data to Back UpOptional: Compress Your DataUpload Data to S3Option 1: Upload a Single FileOption 2: Sync a DirectoryImportant Notes About aws s3 sync--delete (Use with Caution)--exact-timestamps BehaviorBest PracticesAutomate with cron (Optional but Recommended)Restore Files from S3Verify UploadsUseful AWS CLI Options for S3Security Best PracticesTroubleshootingGoogle Cloud StorageKey FeaturesInstall the Google Cloud SDK (Includes gsutil)Restart the ShellInitialize the Google Cloud SDKRunning on Headless Servers (No GUI)Option 1: Manual Login via URLOption 2: Use a Service Account (Recommended for Automation)Authenticate and Set Up AccessSet Your Default ProjectEnable Billing (First-Time Setup)Create a Google Cloud Storage BucketCreate a BucketChoose Storage Class (Optional)Prepare Your Data for BackupCheck Data SizeOptional: Compress Before UploadingUpload to Google Cloud Storage Using gsutilUpload a Single FileSync a DirectoryImportant Note About Folder PlaceholdersSync and Delete Removed Files (Use Carefully)Automate with cronRestore Files from GCSSecurity Best PracticesUse IAM Roles for Principle of Least PrivilegeEnable Bucket EncryptionUse Signed URLs (Optional)Verifying and Listing FilesAccess Control OptionsTroubleshootingBackblaze B2Why Choose Backblaze B2 for Backups?Install rclone on LinuxQuick Install (Curl)Alternative: Verify Binary and Checksum ManuallyOther Option: Use Your Package Manager (May Be Outdated)Debian/UbuntuRHEL/CentOS (via EPEL)Create a Backblaze B2 Account and App KeyConfigure rclone for Backblaze B2Create a Bucket (Optional)Prepare Your Data for BackupBack Up Data to Backblaze B2 Using rcloneSync a DirectoryCopy a FileAutomate Backups with cronRestore From Backblaze B2Restore a FileRestore a Full DirectorySecurity Best PracticesList Contents of a B2 BucketCheck for Specific FileTest File IntegrityUseful rclone OptionsTroubleshootingHow to Test and Validate Your BackupsFor tar ArchivesFor rsyncFor rcloneFor S3ConclusionWrapping Up the Book
Index

Content preview from Beginning Linux SysAdmin: Getting Started with Linux System Administration

N. Asiago OndaraBeginning Linux SysAdminhttps://doi.org/10.1007/979-8-8688-2163-9_10

10. Backup and Disaster Recovery

Neville Asiago Ondara¹

(1)

Thika, Kenya

In any system administration environment, especially when dealing with Linux, ensuring the safety and recoverability of data is critical. Data loss can result from hardware failure, accidental deletion, malicious attacks, or even natural disasters. In this chapter, we’ll cover strategies and tools for backing up data, automating the backup process, and preparing for disaster recovery.

Backup Strategies

The Importance of Regular Backups

Regular backups are the cornerstone of data security. Without proper ...

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Beginning Linux SysAdmin: Getting Started with Linux System Administration

by Neville Asiago Ondara

10. Backup and Disaster Recovery