RH124 - ch11s09

Preface A: Introduction

Section A.1: Orientation to the Classroom Lab Environment

Chapter 1: Accessing the Command Line

Section 1.1: Accessing the Command Line Using the Local Console

Section 1.2: Quiz: Local Console Access Terms

Section 1.3: Accessing the Command Line Using the Desktop

Section 1.4: Guided Exercise: The GNOME 3 Desktop Environment

Section 1.5: Executing Commands Using the Bash Shell

Section 1.6: Quiz: Bash Commands and Keyboard Shortcuts

Section 1.7: Lab: Accessing the Command Line

Chapter 2: Managing Files From the Command Line

Section 2.1: The Linux File System Hierarchy

Section 2.2: Quiz: File System Hierarchy

Section 2.3: Locating Files by Name

Section 2.4: Quiz: Locating Files and Directories

Section 2.5: Managing Files Using Command-Line Tools

Section 2.6: Guided Exercise: Command-Line File Management

Section 2.7: Matching File Names Using Path Name Expansion

Section 2.8: Quiz: Path Name Expansion

Section 2.9: Lab: Managing Files with Shell Expansion

Chapter 3: Getting Help in Red Hat Enterprise Linux

Section 3.1: Reading Documentation Using man Command

Section 3.2: Guided Exercise: Using the man Command

Section 3.3: Reading Documentation Using pinfo Command

Section 3.4: Guided Exercise: Using the pinfo Command

Section 3.5: Reading Documentation in /usr/share/doc

Section 3.6: Guided Exercise: Viewing Package Documentation

Section 3.7: Getting Help From Red Hat

Section 3.8: Guided Exercise: Creating and Viewing an SoS Report

Section 3.9: Lab: Viewing and Printing Help Documentation

Chapter 4: Creating, Viewing, and Editing Text Files

Section 4.1: Redirecting Output to a File or Program

Section 4.2: Quiz: I/O Redirection and Pipelines

Section 4.3: Editing Text Files from the Shell Prompt

Section 4.4: Guided Exercise: Editing Files with Vim

Section 4.5: Editing Text Files with a Graphical Editor

Section 4.6: Guided Exercise: Copying Text Between Windows

Section 4.7: Lab: Creating, Viewing, and Editing Text Files

Chapter 5: Managing Local Linux Users and Groups

Section 5.1: Users and Groups

Section 5.2: Quiz: User and Group Concepts

Section 5.3: Gaining Superuser Access

Section 5.4: Guided Exercise: Running Commands as root

Section 5.5: Managing Local User Accounts

Section 5.6: Guided Exercise: Creating Users Using Command-line Tools

Section 5.7: Managing Local Group Accounts

Section 5.8: Guided Exercise: Managing Groups Using Command-line Tools

Section 5.9: Managing User Passwords

Section 5.10: Guided Exercise: Managing User Password Aging

Section 5.11: Lab: Managing Local Linux Users and Groups

Chapter 6: Controlling Access to Files with Linux File System Permissions

Section 6.1: Linux File System Permissions

Section 6.2: Quiz: Interpreting File and Directory Permissions

Section 6.3: Managing File System Permissions from the Command Line

Section 6.4: Guided Exercise: Managing File Security from the Command Line

Section 6.5: Managing Default Permissions and File Access

Section 6.6: Guided Exercise: Controlling New File Permissions and Ownership

Section 6.7: Lab: Controlling Access to Files with Linux File System Permissions

Chapter 7: Monitoring and Managing Linux Processes

Section 7.1: Processes

Section 7.2: Quiz: Processes

Section 7.3: Controlling Jobs

Section 7.4: Guided Exercise: Background and Foreground Processes

Section 7.5: Killing Processes

Section 7.6: Guided Exercise: Killing Processes

Section 7.7: Monitoring Process Activity

Section 7.8: Guided Exercise: Monitoring Process Activity

Section 7.9: Lab: Monitoring and Managing Linux Processes

Chapter 8: Controlling Services and Daemons

Section 8.1: Identifying Automatically Started System Processes

Section 8.2: Guided Exercise: Identify the Status of systemd Units

Section 8.3: Controlling System Services

Section 8.4: Guided Exercise: Using systemctl to Manage Services

Section 8.5: Lab: Controlling Services and Daemons

Chapter 9: Configuring and Securing OpenSSH Service

Section 9.1: Accessing the Remote Command Line with SSH

Section 9.2: Guided Exercise: Accessing the Remote Command Line

Section 9.3: Configuring SSH Key-based Authentication

Section 9.4: Guided Exercise: Using SSH Key-based Authentication

Section 9.5: Customizing SSH Service Configuration

Section 9.6: Guided Exercise: Restricting SSH Logins

Section 9.7: Lab: Configuring and Securing OpenSSH Service

Chapter 10: Analyzing and Storing Logs

Section 10.1: System Log Architecture

Section 10.2: Quiz: System Logging Components

Section 10.3: Reviewing Syslog Files

Section 10.4: Guided Exercise: Finding Log Entries

Section 10.5: Reviewing systemd Journal Entries

Section 10.6: Guided Exercise: Finding Events With journalctl

Section 10.7: Preserving the systemd Journal

Section 10.8: Guided Exercise: Configure a Persistent systemd Journal

Section 10.9: Maintaining Accurate Time

Section 10.10: Guided Exercise: Adjusting System Time

Section 10.11: Lab: Analyzing and Storing Logs

Chapter 11: Managing Red Hat Enterprise Linux Networking

Section 11.1: Networking Concepts

Section 11.2: Quiz: Networking Concepts

Section 11.3: Validating Network Configuration

Section 11.4: Guided Exercise: Examining Network Configuration

Section 11.5: Configuring Networking with nmcli

Section 11.6: Guided Exercise: Configuring Networking with nmcli

Section 11.7: Editing Network Configuration Files

Section 11.8: Guided Exercise: Editing Network Configuration Files

SectionSection 11.9: Configuring Host Names and Name Resolution

Section 11.10: Guided Exercise: Configuring Host Names and Name Resolution

Section 11.11: Lab: Managing Red Hat Enterprise Linux Networking

Chapter 12: Archiving and Copying Files Between Systems

Section 12.1: Managing Compressed tar Archives

Section 12.2: Guided Exercise: Backing Up and Restoring Files From a tar Archive

Section 12.3: Copying Files Between Systems Securely

Section 12.4: Guided Exercise: Copying Files Over the Network With scp

Section 12.5: Synchronizing Files Between Systems Securely

Section 12.6: Guided Exercise: Synchronizing Two Directories Securely With rsync

Section 12.7: Lab: Archiving and Copying Files Between Systems

Chapter 13: Installing and Updating Software Packages

Section 13.1: Attaching Systems to Subscriptions for Software Updates

Section 13.2: Quiz: Red Hat Subscription Management

Section 13.3: RPM Software Packages and Yum

Section 13.4: Quiz: RPM Software Packages

Section 13.5: Managing Software Updates with yum

Section 13.6: Guided Exercise: Installing and Updating Software with yum

Section 13.7: Enabling yum Software Repositories

Section 13.8: Guided Exercise: Enabling Software Repositories

Section 13.9: Examining RPM Package Files

Section 13.10: Guided Exercise: Working with RPM Package Files

Section 13.11: Lab: Installing and Updating Software Packages

Chapter 14: Accessing Linux File Systems

Section 14.1: Identifying File Systems and Devices

Section 14.2: Quiz: Identifying File Systems and Devices

Section 14.3: Mounting and Unmounting File Systems

Section 14.4: Guided Exercise: Mounting and Unmounting File Systems

Section 14.5: Making Links Between Files

Section 14.6: Guided Exercise: Making Links Between Files

Section 14.7: Locating Files on the System

Section 14.8: Guided Exercise: Locating Files on the System

Section 14.9: Lab: Accessing Linux File Systems

Chapter 15: Using Virtualized Systems

Section 15.1: Managing a Local Virtualization Host

Section 15.2: Quiz: Managing a Local Virtualization Host

Section 15.3: Installing a New Virtual Machine

Section 15.4: Quiz: Installing a New Virtual Machine

Section 15.5: Quiz: Using Virtualized Systems

Chapter 16: Comprehensive Review

Section 16.1: Red Hat System Administration I Comprehensive Review

Section 16.2: Lab: Comprehensive Review

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Configuring Host Names and Name Resolution

Display and change system host name and name resolution configuration.

Objectives

After completing this section, students should be able to configure and test system host name and name resolution.

Changing the system host name

Configuring host names and name resolution

The hostname command displays or temporarily modifies the system's fully qualified host name.

[root@desktopX ~]# hostname
desktopX.example.com

A static host name may be specified in the /etc/hostname file. The hostnamectl command is used to modify this file and may be used to view the status of the system's fully qualified host name. If this file does not exist, the host name is set by a reverse DNS query once the interface has an IP address assigned.

[root@desktopX ~]# hostnamectl set-hostname desktopX.example.com
[root@desktopX ~]# hostnamectl status
   Static hostname: desktopX.example.com
         Icon name: computer
           Chassis: n/a
        Machine ID: 9f6fb63045a845d79e5e870b914c61c9
           Boot ID: aa6c3259825e4b8c92bd0f601089ddf7
    Virtualization: kvm
  Operating System: Red Hat Enterprise Linux Server 7.0 (Maipo)
       CPE OS Name: cpe:/o:redhat:enterprise_linux:7.0:GA:server
            Kernel: Linux 3.10.0-97.el7.x86_64
      Architecture: x86_64
[root@desktopX ~]# cat /etc/hostname
desktopX.example.com

Important

The static host name is stored in /etc/hostname. Previous versions of Red Hat Enterprise Linux stored the host name as a variable in the /etc/sysconfig/network file.

Configuring name resolution

The stub resolver is used to convert host names to IP addresses or the reverse. The contents of the file /etc/hosts are checked first.

[root@desktopX ~]# cat /etc/hosts
127.0.0.1       localhost localhost.localdomain localhost4 localhost4.localdomain4
::1             localhost localhost.localdomain localhost6 localhost6.localdomain6

172.25.254.254 classroom.example.com
172.25.254.254 content.example.com

The getent hosts hostname command can be used to test host name resolution with the /etc/hosts file.

If an entry is not found in that file, the stub resolver looks for the information from a DNS nameserver. The /etc/resolv.conf file controls how this query is done:

nameserver: the IP address of a nameserver to query. Up to three nameserver directives may be given to provide backups if one is down.
search: a list of domain names to try with a short host name. Both this and domain should not be set in the same file; if they are, the last instance wins. See resolv.conf(5) for details.

[root@desktopX ~]# cat /etc/resolv.conf
# Generated by NetworkManager
domain example.com
search example.com
nameserver 172.25.254.254

NetworkManager will update the /etc/resolv.conf file using DNS settings in the connection configuration files. Use the nmcli to modify the connections.

[root@desktopX ~]# nmcli con mod ID ipv4.dns IP
[root@desktopX ~]# nmcli con down ID
[root@desktopX ~]# nmcli con up ID
[root@desktopX ~]# cat /etc/sysconfig/network-scripts/ifcfg-ID
...
DNS1=8.8.8.8
...

The default behavior of nmcli con mod ID ipv4.dns IP is to replace any previous DNS settings with the new IP list provided. A +/- symbol in front of the ipv4.dns argument will add or remove an individual entry.

[root@desktopX ~]# nmcli con mod ID +ipv4.dns IP

The host HOSTNAME command can be used to test DNS server connectivity.

[root@desktopX ~]# host classroom.example.com
classroom.example.com has address 172.25.254.254
[root@desktopX ~]# host 172.25.254.254
254.254.25.172.in-addr.arpa domain name pointer classroom.example.com.

Important

If DHCP is in use, /etc/resolv.conf is automatically rewritten as interfaces are started, unless you specify PEERDNS=no in the relevant interface configuration files. The change can be made with nmcli.

[root@desktopX ~]# nmcli con mod "System eth0" ipv4.ignore-auto-dns yes

References

nmcli(1), hostnamectl(1), hosts(5), getent(1), host(1), and resolv.conf(5) man pages

Additional information may be available in the chapter on configuring host names in the Red Hat Enterprise Linux Networking Guide for Red Hat Enterprise Linux 7, which can be found at https://access.redhat.com/documentation/

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RH124 Chapter 15 Lab 3: Install zsh Package

VictoriaB97

16 sty 2024

Hello,I am trying to finish up Lab 3 of the Chapter 15 Comprehensive Review Labs in RH124, and when I type in sudo dnf install zsh for the 6th specification of the lab, I get an error message basically saying that it failed to download metadata for the repo 'ansible-2.9-for-rhel-9-x86_64-rpms', and that they could not download repomd.xml. It provided a 404 status code.Can someone please let me know what the problem is, and if there is a current workaround? Thanks.

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Red Hat System Administration I | Guided Exercise: Explain and Investigate RPM Software Pack

AbeHiero

10 lis 2023

I cannot start the lab with command: lab start software-rpm. I get this error:ModuleNotFoundError: No module named 'rhcsa-classroom'Script software-rpm not in course library rhcsa-classroom Anyone else see this?

172

Red Hat System Administration I (RH124)

Haley_Ruccio

19 lip 2023

The first of two courses covering the core system administration tasks needed to manage Red Hat Enterprise Linux serversRed Hat System Administration I (RH124) is designed for IT professionals without previous Linux system administration experience. The course provides students with Linux administration competence by focusing on core administration tasks. This course also provides a foundation for students who plan to become full-time Linux system administrators by introducing key command-line concepts and enterprise-level tools. This course is the first of a two-course series that takes a computer professional without Linux system administration knowledge to become a fully capable Linux administrator. These concepts are further developed in the follow-on course, Red Hat System Administration II (RH134).This course is based on Red Hat® Enterprise Linux 9.0.Course content summaryIntroduce Linux and the Red Hat Enterprise Linux ecosystem.Run commands and view shell environments.Manage, organize, and secure files.Manage users, groups and user security policies.Control and monitor systemd services.Configure remote access using the web console and SSH.Configure network interfaces and settings.Manage software using DNFAudience for this courseThe primary persona is a technical professional with current or pending responsibilities as a Linux enterprise or cloud system administrator.This course is popular in Red Hat Academy, and is targeted at the student who is planning to become a technical professional using Linux.Prerequisites for this courseBasic technical user skills with computer applications on some operating systems are expected.Take our free assessment to gauge whether this offering is the best fit for your skills.Technology considerationsThere are no special technical requirements for this course.This course is not designed for bring your own device (BYOD).Internet access is not required but is recommended so that students can research and browse Red Hat online resources.

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Revision: rh124-7-1b00421