KAHIBARO
3. PART III Intermediate System Administration
Table of Contents
Overview
Part III moves from using Linux to administering it. You’ll start thinking like the person responsible for keeping systems running, secure, and recoverable, not just as a user running commands.
This part assumes you are already comfortable with:
- Navigating the filesystem
- Using the shell and basic scripting
- Managing packages
- Understanding basic concepts like users, permissions, and processes
You’ll now apply those skills to real-world administration tasks.
Goals of Part III
By the end of this part, you should be able to:
- Understand and control how services start, stop, and log via
systemd - Manage disks, partitions, and filesystems, and handle backups/archives
- Configure basic networking and troubleshoot common connectivity issues
- Create and manage multiple users and groups on a shared system
- Monitor the health and performance of a Linux system
- Design and implement basic backup and restore strategies
- Apply foundational security measures to harden a Linux host
You are not yet building complex production clusters or doing deep kernel tuning—that comes later—but you will cover everything needed to run a small server or workstation responsibly.
How This Part Is Structured
Part III is divided into practical topics, each focusing on a key admin area:
- Systemd and Service Management
How Linux starts, stops, and supervises services on modern distributions: - Understanding
systemdas the init system and service manager - Using
systemctlto manage services and boot targets - Viewing and filtering logs with
journalctl - Defining simple custom services for your own scripts or apps
- Storage and Filesystems
Working with disks and on-disk data structures: - Mapping physical devices to partitions
- Choosing and creating common filesystems (like EXT4, XFS, Btrfs)
- Mounting and unmounting filesystems (both temporarily and persistently)
- Checking disk space and usage patterns
- Using classic archiving and compression tools for backups or transfers
- Networking Fundamentals
Giving your system an identity on a network and keeping it reachable: - Understanding IP addresses, subnets, and basic routing concepts
- How DNS and hostnames fit into name resolution
- Using standard network diagnostic tools
- Editing and applying network configuration on typical Linux systems
- User and Group Administration
Scaling beyond a single personal account: - Where account information is stored
- Creating, modifying, and removing user accounts
- Setting password aging and complexity policies
- Group-based access control and membership management
- Basic shell customization for users
- System Monitoring
Watching what the system is doing, in real time and historically: - Checking CPU, RAM, and swap usage
- Monitoring disk utilization and I/O behavior
- Understanding the role of
/var/logand key system logs - Measuring and troubleshooting slow boots
- Verifying that essential services are running correctly
- Backup and Restore
Preparing for failure and human mistakes: - Designing simple backup strategies and schedules
- Using
rsyncefficiently for local and remote backups - Creating and restoring
tararchives - Understanding snapshot-based backup systems conceptually
- Automating backup routines with existing tools and scripts
- Basic System Security
Protecting a single host from common threats: - Enabling and managing host firewalls (UFW or firewalld)
- Controlling authentication rules (passwords, lockouts, etc.)
- Hardening SSH access for remote logins
- Recognizing the role of MAC systems like SELinux and AppArmor
- Getting started with intrusion detection tools and ideas
Each of these topics focuses on practical, admin-level tasks. You’ll see common commands, configuration file locations, and workflows that most system administrators use daily.
How to Approach This Part
To get the most from Part III:
- Use a test machine or virtual machine
You will change system-wide settings. A VM lets you experiment freely. - Make small, reversible changes
Before editing configuration files, make backups like:
cp /etc/somefile.conf /etc/somefile.conf.bak - Practice end-to-end workflows
Don’t just learn individual commands. For example: - Install a service
- Enable it with
systemd - Expose it on the network
- Monitor its logs
- Back up its data
- Connect the chapters
For example: - Use user and group management together with filesystem permissions.
- Combine
rsyncandtarwith cron (from shell scripting) to automate backups. - Relate firewall rules to the network services you configure.
As you progress, you’ll transition from “Can I do this on my machine?” to “Could I responsibly maintain this system for others?”, which is the core mindset of a Linux system administrator.
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