Red Hat Enterprise Linux 7 Troubleshooting

Introduction

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Course Objectives

  • This course is designed to prepare an administrator who has a firm Linux or UNIX background, to troubleshoot Red Hat Enterprise Linux.

  • After completing this course, you should be able to understand and demonstrate how to troubleshoot a Red Hat Enterprise Linux environment including using:

    • System tools

    • SELinux

    • firewalld

    • iSCSI, and more

  • This course is targeted at platform consultants who need to learn about troubleshooting Red Hat Enterprise Linux.

Copyright ©2012-2019 Red Hat, Inc. - 1.5

Provisioning Your Lab Environment

The entire Lab Environment Setup section is extremely important. Please read and understand it before continuing with the course. Most questions will be answered here.

  1. Log in to the OPENTLC Labs portal.

  2. Go to Services -> Catalogs.

  3. All Services/OPENTLC Datacenter Infrastructure Labs

  4. On the left, click RHEL 7 Troubleshooting Lab.

  5. On the right, click Order.

  6. On the bottom right, click Submit.

    • You will receive an email with information on accessing your environment

    • It takes about 20 minutes for your lab to be accessible

    • Your instructor's server is accessible via the hostname rhel-GUID.rhpds.opentlc.com where _GUID_ is replaced with a unique identifier for your lab

You will get this hostname and GUID in the email mentioned above.
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Lab Environment Overview

  • Most hands-on lab exercises use two computer systems:

    • desktop = hostname desktop1.example.com

    • server = hostname server1.example.com

  • Both machines have a standard user account:

    • user = student

    • password = r3dh@t1!

  • The root password on both systems is r3dh@t1!.

  • Any other accounts also use the r3dh@t1! password.

    Remember, in this environment, your student number will always be 1.

  • Your IPv4 network is 192.168.0.0/24.

  • The rhel-GUID.rhpds.opentlc.com system also acts as a central utility server which provides a router for the classroom networks as well as DNS, DHCP, HTTP, and other content services.

Copyright ©2012-2019 Red Hat, Inc. - 1.5

Classroom Machines

Machine NameIP AddressRole

desktop1.example.com

192.168.0.1

Student "client" computer

server1.example.com

192.168.0.101

Student "server" computer

External: rhel-GUID.rhpds.opentlc.com Internal: instructor.example.com

192.168.0.254

Classroom utility server (accessible externally)

Your lab environment exists totally within the cloud. You have direct access to only one system, the instructor server. When you provision your lab via the OPENTLC CloudForms system, you will receive an email that contains the external host name and IP address for your instructor server. You will not, however, have root access to the instructor server.

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Accessing Your System via SSH

  • You access your instructor system using an SSH client pointed to rhel-GUID.rhpds.opentlc.com.

  • The root passwords for the systems are locked out.

  • You must log in using your OPENTLC SSO account (the same login that you used to provision the lab) plus your OPENTLC SSO SSH Key.

You must use SSH to connect to the instructor system using your OPENTLC SSO username + SSH Key. You cannot log in to the instructor system as root.

References

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Accessing Your Desktop System Via the Web GUI

  • Your desktop system is accessible via an HTML5 remote console technology called Guacamole.

  • You do not need to install or run anything other than a web browser on your side.

  • To access your remote console, point your web browser to the Guacamole URL that is provided in the e-mail sent to you from OPENTLC.

  • Use the provided username and password to log in to Guacamole.

  • When logged into Guacamole, start the web GUI by clicking Desktop-VNC.

    You can also start web-based SSH sessions for the desktop and server systems by clicking their names in the Guacamole landing page.
Type the URL above correctly. Include https and replace GUID with your lab’s assigned GUID.
One drawback of using Guacamole is that it is difficult to cut and paste text from your physical system. If you want to cut and paste, you should use SSH to connect to the instructor server, and then use SSH to connect to the lab systems as described later in this module.
Copyright ©2012-2019 Red Hat, Inc. - 1.5

Adjusting the Desktop Resolution in the Web GUI

If your GUI’s resolution is hard to see, lower the resolution as follows:

  1. Click the Red Hat Shadowman logo at the bottom left corner.

  2. Type display configuration in the Search box.

  3. Click the Display Configuration Item that appears, to start the control panel.

  4. Click the tiny white box with green arrows labeled "Show list of available display resolutions."

  5. Double-click the resolution that works best for you.

  6. Click Apply.

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Using the Instructor Server to Connect via SSH

If you used SSH to connect directly into the classroom server, you can then use SSH to connect to the desktop or server system as the student user:

  1. Enter the following command:

    bash-4.2$ ssh student@desktop1.example.com

  2. Answer yes when prompted.

  3. Enter the student user’s password, which was provided earlier.

Copyright ©2012-2019 Red Hat, Inc. - 1.5

Download Lab RPMs

Download and uncompress the lab RPMs on both desktop1.example.com and server1.example.com:

# cd /root
# wget https://www.opentlc.com/download/RTlabscripts.tar.gz
# tar -xf RTlabscripts.tar.gz
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Module Completion

Nice job!

Click the button below to complete this module of the course:


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