Red Hat System Administration I

RH124

Welcome

Course Objectives and Structure

Schedule

Orientation to the Classroom Lab Environment

Internationalization

Chapter 1: Getting Started with Red Hat Enterprise Linux

Goal: Describe and define open source, Linux, Linux distributions, and Red Hat Enterprise Linux.

Objectives:

• Define and explain the purpose of Linux, open source, Linux distributions, and Red Hat Enterprise Linux.

Quiz: Getting Started with Red Hat Enterprise Linux

Summary

• Open source software is software with source code that anyone can freely use, study, modify, and share.
• A Linux distribution is an installable operating system constructed from a Linux kernel and supporting user programs and libraries.
• Red Hat participates in supporting and contributing code to open source projects, sponsors and integrates project software into community-driven distributions, and stabilizes the software to offer it as supported enterprise-ready products.
• Red Hat Enterprise Linux is Red Hat's open source, enterprise-ready, commercially-supported Linux distribution.

Chapter 2: Accessing the Command Line

Goal: Log in to a Linux system and run simple commands using the shell.

Objectives:

• Log in to a Linux system on a local text console and run simple commands using the shell.

• Log in to a Linux system using the GNOME 3 desktop environment and run commands from a shell prompt in a terminal program.

• Save time by using tab completion, command history, and command editing shortcuts to run commands in the Bash shell.

Quiz: Accessing the Command Line

Guided Exercise: Accessing the Command Line Using the Desktop

Quiz: Executing Commands Using the Bash Shell

Lab: Accessing the Command Line

Summary

• The Bash shell is a command interpreter that prompts interactive users to specify Linux commands.
• Many commands have a --help option that displays a usage message or screen.
• Using workspaces makes it easier to organize multiple application windows.
• The Activities button located at the upper-left corner of the top bar provides an overview mode that helps a user organize windows and start applications.
• The file command scans the beginning of a file's contents and displays what type it is.
• The head and tail commands display the beginning and end of a file, respectively.
• You can use Tab completion to complete file names when typing them as arguments to commands.

Chapter 3: Managing Files From the Command Line

Goal: Copy, move, create, delete, and organize files while working from the Bash shell.

Objectives:

• Describe how Linux organizes files, and the purposes of various directories in the file-system hierarchy.

• Specify the location of files relative to the current working directory and by absolute location, determine and change your working directory, and list the contents of directories.

• Create, copy, move, and remove files and directories.

• Make multiple file names reference the same file using hard links and symbolic (or "soft") links.

• Efficiently run commands affecting many files by using pattern matching features of the Bash shell.

Quiz: Describing Linux File System Hierarchy Concepts

Quiz: Specifying Files by Name

Guided Exercise: Managing Files Using Command-line Tools

Guided Exercise: Making Links Between Files

Quiz: Matching File Names with Shell Expansions

Lab: Managing Files from the Command Line

Summary

• Files on a Linux system are organized into a single inverted tree of directories, known as a file-system hierarchy.
• Absolute paths start with a / and specify the location of a file in the file-system hierarchy.
• Relative paths do not start with a / and specify the location of a file relative to the current working directory.
• Five key commands are used to manage files: mkdir, rmdir, cp, mv, and rm.
• Hard links and soft links are different ways to have multiple file names point to the same data.
• The Bash shell provides pattern matching, expansion, and substitution features to help you efficiently run commands.

Chapter 4: Getting Help in Red Hat Enterprise Linux

Goal: Resolve problems by using local help systems.

Objectives:

• Find information in local Linux system manual pages.

• Find information from local documentation in GNU Info.

Guided Exercise: Reading Manual Pages

Guided Exercise: Reading Info Documentation

Lab: Getting Help in Red Hat Enterprise Linux

Summary

• Man pages are viewed with the man command and provide information on components of a Linux system, such as files, commands, and functions.
• By convention, when referring to a man page the name of a page is followed by its section number in parentheses.
• Info documents are viewed with the pinfo command and are made up of a collection of hypertext nodes, providing information about software packages as a whole.
• The navigational keystrokes used by man and pinfo are slightly different.

Chapter 5: Creating, Viewing, and Editing Text Files

Goal: Create, view, and edit text files from command output or in a text editor.

Objectives:

• Save command output or errors to a file with shell redirection, and process command output through multiple command-line programs with pipes.

• Create and edit text files using the vim editor.

• Use shell variables to help run commands, and edit Bash startup scripts to set shell and environment variables to modify the behavior of the shell and programs run from the shell.

Quiz: Redirecting Output to a File or Program

Guided Exercise: Editing Text Files from the Shell Prompt

Guided Exercise: Changing the Shell Environment

Lab: Creating, Viewing, and Editing Text Files

Summary

• Running programs, or processes, have three standard communication channels, standard input, standard output, and standard error.
• You can use I/O redirection to read standard input from a file or write the output or errors from a process to a file.
• Pipelines can be used to connect standard output from one process to standard input of another process, and can be used to format output or build complex commands.
• You should know how to use at least one command-line text editor, and Vim is generally installed.
• Shell variables can help you run commands and are unique to a particular shell session.
• Environment variables can help you configure the behavior of the shell or the processes it starts.

Chapter 6: Managing Local Users and Groups

Goal: Create, manage, and delete local users and groups and administer local password policies.

Objectives:

• Describe the purpose of users and groups on a Linux system.

• Switch to the superuser account to manage a Linux system, and grant other users superuser access using the sudo command.

• Create, modify, and delete locally defined user accounts.

• Create, modify, and delete locally defined group accounts.

• Set a password management policy for users, and manually lock and unlock user accounts.

Quiz: Describing User and Group Concepts

Guided Exercise: Gaining Superuser Access

Guided Exercise: Managing Local User Accounts

Guided Exercise: Managing Local Group Accounts

Guided Exercise: Managing User Passwords

Lab: Managing Local Users and Groups

Summary

• There are three main types of user account: the superuser, system users, and regular users.
• A user must have a primary group and may be a member of one or more supplementary groups.
• The three critical files containing user and group information are /etc/passwd, /etc/group, and /etc/shadow.
• The su and sudo commands can be used to run commands as the superuser.
• The useradd, usermod, and userdel commands can be used to manage users.
• The groupadd, groupmod, and groupdel commands can be used to manage groups.
• The chage command can be used to configure and view password expiration settings for users.

Chapter 7: Controlling Access to Files

Goal: Set Linux file-system permissions on files and to interpret the security effects of different permission settings.

Objectives:

• List the file system permissions on files and directories, and interpret the effect of those permissions on access by users and groups.

• Change the permissions and ownership of files using command-line tools.

• Control the default permissions of new files created by users, explain the effect of special permissions, and use special permissions and default permissions to set the group owner of files created in a particular directory.

Quiz: Interpreting Linux File System Permissions

Guided Exercise: Managing File System Permissions from the Command Line

Guided Exercise: Managing Default Permissions and File Access

Lab: Controlling Access to Files

Summary

• Files have three categories to which permissions apply. A file is owned by a user, a single group, and other users. The most specific permission applies. User permissions override group permissions and group permissions override other permissions.
• The ls command with the -l option expands the file listing to include both the file permissions and ownership.
• The chmod command changes file permissions from the command line. There are two methods to represent permissions, symbolic (letters) and numeric (digits).
• The chown command changes file ownership. The -R option recursively changes the ownership of a directory tree.
• The umask command without arguments displays the current umask value of the shell. Every process on the system has a umask. The default umask values for Bash are defined in the /etc/profile and /etc/bashrc files.

Chapter 8: Monitoring and Managing Linux Processes

Goal: Evaluate and control processes running on a Red Hat Enterprise Linux system.

Objectives:

• Get information about programs running on the system so that you can determine status, resource use, and ownership, so you can control them.

• Use Bash job control to manage multiple processes started from the same terminal session.

• Control and terminate processes that are not associated with your shell, and forcibly end user sessions and processes.

• Describe what load average is and determine processes responsible for high resource use on a server.

Quiz: Listing Processes

Guided Exercise: Controlling Jobs

Guided Exercise: Killing Processes

Guided Exercise: Monitoring Process Activity

Lab: Monitoring and Managing Linux Processes

Summary

• A process is a running instance of an executable program. Processes are assigned a state, which can be running, sleeping, stopped, or zombie. The ps command is used to list processes.
• Each terminal is its own session and can have foreground process and independent background processes. The jobs command displays processes within a terminal session.
• A signal is a software interrupt that reports events to an executing program. The kill, pkill, and killall commands use signals to control processes.
• Load average is an estimate of how busy the system is. To display load average values, you can use the top, uptime, or w command.

Chapter 9: Controlling Services and Daemons

Goal: Control and monitor network services and system daemons using Systemd.

Objectives:

• List system daemons and network services started by the systemd service and socket units.

• Control system daemons and network services, using systemctl.

Guided Exercise: Identifying Automatically Started System Processes

Guided Exercise: Controlling System Services

Lab: Controlling Services and Daemons

Summary

• systemd provides a method for activating system resources, server daemons, and other processes, both at boot time and on a running system.
• Use the systemctl to start, stop, reload, enable, and disable services.
• Use the systemctl status command to determine the status of system daemons and network services started by systemd.
• The systemctl list-dependencies command lists all service units upon which a specific service unit depends.
• systemd can mask a service unit so that it does not run even to satisfy dependencies.

Chapter 10: Configuring and Securing SSH

Goal: Configure secure command-line service on remote systems, using OpenSSH.

Objectives:

• Log in to a remote system and run commands using ssh.

• Configure key-based authentication for a user account to log in to remote systems securely without a password.

• Restrict direct logins as root and disable password-based authentication for the OpenSSH service.

Guided Exercise: Accessing the Remote Command Line

Guided Exercise: Configuring SSH Key-based Authentication

Guided Exercise: Customizing OpenSSH Service Configuration

Lab: Configuring and Securing SSH

Summary

• The ssh command allows users to access remote systems securely using the SSH protocol.
• A client system stores remote servers' identities in ~/.ssh/known_hosts and /etc/ssh/ssh_known_hosts.
• SSH supports both password-based and key-based authentication.
• The ssh-keygen command generates an SSH key pair for authentication. The ssh-copy-id command exports the public key to remote systems.
• The sshd service implements the SSH protocol on Red Hat Enterprise Linux systems.
• It is a recommended practice to configure sshd to disable remote logins as root and to require public key authentication rather than password-based authentication.

Chapter 11: Analyzing and Storing Logs

Goal: Locate and accurately interpret logs of system events for troubleshooting purposes.

Objectives:

• Describe the basic logging architecture used by Red Hat Enterprise Linux to record events.

• Interpret events in relevant syslog files to troubleshoot problems or review system status.

• Find and interpret entries in the system journal to troubleshoot problems or review system status.

• Configure the system journal to preserve the record of events when a server is rebooted.

• Maintain accurate time synchronization using NTP and configure the time zone to ensure correct time stamps for events recorded by the system journal and logs.

Quiz: Describing System Log Architecture

Guided Exercise: Reviewing Syslog Files

Guided Exercise: Reviewing System Journal Entries

Guided Exercise: Preserving the System Journal

Guided Exercise: Maintaining Accurate Time

Lab: Analyzing and Storing Logs

Summary

• The systemd-journald and rsyslog services capture and write log messages to the appropriate files.
• The /var/log directory contains log files.
• Periodic rotation of log files prevent them from filling up the file system space.
• The systemd journals are temporary and do not persist across reboot.
• The chronyd service helps to synchronize time settings with a time source.
• The time zone of the server can be updated based on its location.

Chapter 12: Managing Networking

Goal: Configure network interfaces and settings on Red Hat Enterprise Linux servers.

Objectives:

• Describe fundamental concepts of network addressing and routing for a server.

• Test and inspect current network configuration with command-line utilities.

• Manage network settings and devices using nmcli.

• Modify network settings by editing configuration files.

• Configure a server's static host name and its name resolution, and test the results.

Quiz: Describing Networking Concepts

Guided Exercise: Validating Network Configuration

Guided Exercise: Configuring Networking from the Command Line

Guided Exercise: Editing Network Configuration Files

Guided Exercise: Configuring Host Names and Name Resolution

Lab: Managing Networking

Summary

• The TCP/IP network model is a simplified, four-layered set of abstractions that describes how different protocols interoperate in order for computers to send traffic from one machine to another over the Internet.
• IPv4 is the primary network protocol used on the Internet today. IPv6 is intended as an eventual replacement for the IPv4 network protocol. By default, Red Hat Enterprise Linux operates in dual-stack mode, using both protocols in parallel.
• NetworkManager is a daemon that monitors and manages network configuration.
• The nmcli command is a command-line tool for configuring network settings with NetworkManager.
• The system's static host name is stored in the /etc/hostname file. The hostnamectl command is used to modify or view the status of the system's host name and related settings. The hostname command displays or temporarily modifies the system's host name.

Chapter 13: Archiving and Transferring Files

Goal: Archive and copy files from one system to another.

Objectives:

• Archive files and directories into a compressed file using tar, and extract the contents of an existing tar archive.

• Transfer files to or from a remote system securely using SSH.

• Synchronize the contents of a local file or directory with a copy on a remote server.

Guided Exercise: Managing Compressed Tar Archives

Guided Exercise: Transferring Files Between Systems Securely

Guided Exercise: Synchronizing Files Between Systems Securely

Lab: Archiving and Transferring Files

Summary

• The tar command creates an archive file from a set of files and directories, extracts files from the archive, and lists the contents of an archive.
• The tar command provides a set of different compression methods reduce archive size.
• Besides providing a secure remote shell, the SSH service also provides the scp and sftp commands as secure ways to transfer files from and to a remote system running the SSH server.
• The rsync command securely and efficiently synchronizes files between two directories, either one of which can be on a remote system.

Chapter 14: Installing and Updating Software Packages

Goal: Download, install, update, and manage software packages from Red Hat and Yum package repositories.

Objectives:

• Register a system to your Red Hat account and assign it entitlements for software updates and support services using Red Hat Subscription Management.

• Explain how software is provided as RPM packages, and investigate the packages installed on the system with Yum and RPM.

• Find, install, and update software packages using the yum command.

• Enable and disable use of Red Hat or third-party Yum repositories by a server.

• Explain how modules allow installation of specific versions of software, list, enable, and switch module streams, and install and update packages from a module.

Quiz: Registering Systems for Red Hat Support

Guided Exercise: Explaining and Investigating RPM Software Packages

Guided Exercise: Installing and Updating Software Packages with Yum

Guided Exercise: Enabling Yum Software Repositories

Guided Exercise: Managing Package Module Streams

Lab: Installing and Updating Software Packages

Summary

• Red Hat Subscription Management provides tools to entitle machines to product subscriptions, get updates to software packages, and track information about support contracts and subscriptions used by the systems.
• Software is provided as RPM packages, which make it easy to install, upgrade, and uninstall software from the system.
• The rpm command can be used to query a local database to provide information about the contents of installed packages and install downloaded package files.
• yum is a powerful command-line tool that can be used to install, update, remove, and query software packages.
• Red Hat Enterprise Linux 8 uses Application Streams to provide a single repository to host multiple versions of an application's packages and its dependencies.

Chapter 15: Accessing Linux File Systems

Goal: Access, inspect, and use existing file systems on storage attached to a Linux server.

Objectives:

• Explain what a block device is, interpret the file names of storage devices, and identify the storage device used by the file system for a particular directory or file.

• Access file systems by attaching them to a directory in the file system hierarchy.

• Search for files on mounted file systems using the find and locate commands.

Quiz: Identifying File Systems and Devices

Guided Exercise: Mounting and Unmounting File Systems

Guided Exercise: Locating Files on the System

Lab: Accessing Linux File Systems

Summary

• Storage devices are represented by a special file type called block device.
• The df command reports total disk space, used disk space, and free disk space on all mounted regular file systems.
• The mount command allows the root user to manually mount a file system.
• All processes need to stop accessing the mount point in order to successfully unmount the device.
• The removable storage devices are mounted in the /run/media directory when using the graphical environment.
• The find command performs a real-time search in the local file systems to find files based on search criteria.

Chapter 16: Analyzing Servers and Getting Support

Goal: Investigate and resolve issues in the web-based management interface, getting support from Red Hat to help solve problems.

Objectives:

• Activate the Web Console management interface to remotely manage and monitor the performance of a Red Hat Enterprise Linux server.

• Describe key resources available through the Red Hat Customer Portal, and find information from Red Hat documentation and the Knowledgebase.

• Analyze servers for issues, remediate or resolve them, and confirm the solution with Red Hat Insights.

Guided Exercise: Analyzing and Managing Remote Servers

Guided Exercise: Getting Help from Red Hat Customer Portal

Quiz: Detecting and Resolving Issues with Red Hat Insights

Summary

• Web Console is a web-based management interface to your server based on the open source Cockpit service.
• Web Console provides graphs of system performance, graphical tools to manage system configuration and inspect logs, and an interactive terminal interfaces.
• Red Hat Customer Portal provides you with access to documentation, downloads, optimization tools, support case management, and subscription and entitlement management for your Red Hat products.
• redhat-support-tool is a command-line tool to query Knowledgebase and work with support cases from the server's command line.
• Red Hat Insights is a SaaS-based predictive analytics tool to help you identify and remediate threats to your systems' security, performance, availability, and stability.

Chapter 17: Comprehensive Review

Lab: Managing Files from the Command Line

Lab: Managing Users and Groups, Permissions and Processes

Lab: Configuring and Managing a Server

Lab: Managing Networks

Lab: Mounting Filesystems and Finding Files