OPS235 Lab 1 - CentOS7 - HD2

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LAB PREPARATION

If you have a removable hard drive (as opposed to a solid state drive), you will be creating a Linux host machine first to support virtual machines that you will create later in lab 2.

Purpose of Lab 1

In order to save money and resources when learning to install, to manage, and to connect Linux machines to form networks, we will be using Virtual Machines for this course.

  • lab1: Create a Centos7 Host machine (c7host) on your removable hard drive.
  • Lab2: Install a Virtual package on your host machine called KVM which will be used to create 3 remaining Virtual Machines (VMs) that will be used to learn about Linux system administration for the remainder of this course.


It is ESSENTIAL to have a removable hard drive with a minimum storage capacity of 240 GB to perform your lab sessions and provide a host for your other Centos7 host and other VMs that you will create in lab2. Due to space requirements, you are NOT permitted to share this removable hard drive with any other course material than our OPS235 course.


Main Objectives

  • Correctly install the CentOS 7 FULL INSTALL DVD (c7host) on your removable hard drive.
  • Note common Linux commands and record them in your lab1 logbook.
  • Use Shell scripts to generate a post-install report for your Centos7 host VM.
  • Disable Linux Kernel security enhancements to allow easier internal networking connections (to be reactivated in a later lab).


Minimum Required Materials
 Linux Command Reference
CentOS7FULL INSTALL DVD
Removable SATA Hard Disk
Lab Log Book
(lab 1)
 Package Management

rpm
yum
System Information
hostname
uname
ps
lsblk
Networking
ifconfig
route
nslookup

 Miscellaneous

grep
wc
pwd
ls
more
file
wget
chmod
vi

Matrix on-line tutorials
  • Linux Basics:
    /home/murray.saul/linux-basics
  • Using the vi Text Editor:
    /home/murray.saul/vi-tutorial
  • Shell Scripting - Part I (Scripting Basics):
    /home/murray.saul/scripting-1

INVESTIGATION 1: CREATE AND INSTALL HOST MACHINE (c7host)

In this lab, you will learn how to install your Centos Full Install DVD as a host machine. Make certain to record your observations in your lab1 logbook.


Part 1: Using KVM to Create a New Virtual Machine (VM)

c7host Machine Details:

  • Name: c7host
  • Boot media / Installation: CentOS7 Full Install DVD
  • Disk space: 240GB
  • CPUs: 1


Perform the following steps:

The Installation Summary screen provides flexibly when configuring to install on your computer.
  1. Although the images may be a little out of date (i.e. not exact), you can refer to this listing of installation screenshots for general reference:
    [installation screen-shots ]
  2. Insert your removable SATA hard disk into the drive tray.
  3. Set your computer's drive selector switch to external (a.k.a position #4).
  4. Power up the computer and insert the CentOS 7 Installation DVD into the DVD drive, then power-off computer.
  1. Power on the computer again, press the F9 key a few times upon boot, and select SATA5 near the bottom on the menu to boot from your DVD. After booting from the DVD, select from the installation menu: Install Centos7.

    Note: If you experience unreadable display after you boot into your installed system, you can redo the install, but select from the install menu: Troubleshooting and then select Install in Basic Graphics Mode.

  2. Next, you will be prompted for a language. In the first screen, select language English with subselection English-Canada and then click the Continue button on the bottom right-hand screen.
  3. The Install Summary should now appear. This screen allows the installer to customize their Centos7 system prior to installation.
  4. Configure the following installation settings from the Install Summary Screen:

    DATE & TIME:
    • Click on the Map to select Toronto area (you may also select from the drop-down menu section)
    • Click the DONE button at the top-left corner to finish and return to the Installation Summary screen.

    NETWORK & HOSTNAME:
    • Select the default Ethernet connection and click the button on the top right-hand side to change the setting from OFF to ON.
    • At the bottom left-hand corner type the hostname: c7host (all lowercase letters)
    • Review your settings, then click the DONE button at the top-left corner to finish and return to the Installation Summary screen.

    SOFTWARE SELECTION:
    • Select the software packages labelled: Gnome Desktop
    • Click the DONE button at the top-left corner to finish and return to the Installation Summary screen.

  5. Although the Centos installtion program can provide suggestions on how to partition your hard disk, you will be customizing partitions for your hard disk. This custom partitioning is important since it will have consequences on future labs that you perform (especially for lab2).

    Proceed to Part 2 to customize your partitions.

Part 2: Creating Partitions

The next step is to perform a custom installation for your Centos7 virtual machine using the Centos7 Full DVD. Upon creation of your c7host virtual machine, The VMware Workstation application will automatically simulate a "boot" to allow you to complete the installation process to create the Centos7 operating system on that virtual machine.

Note.png
Mount Points and Linux File System Types
Similar to other Operating Systems like windows fat / vfat / ntfs file system types, it is good to know a few common file system types in Linux for comparison:
  • xfs:   Newer filesystem (fast transfer rates for large files, Journaling)
  • ext4:   Newer filesystem supporting large files and Journaling (used in for this lab)
  • ext2:   Stable filesystem popular for databases (no journaling)
Carefully verify partition mount-names and sizes prior to proceeding with install. Check installation screenshots link for verification.


Perform the Following Steps:
  1. From the installation summary screen, click Installation Destination.
  2. In the installation destination screen, select the destination option: I will configure partitioning and then click Done.
  3. The manual partitioning screen should appear.
  4. If you have used your hard disk for previous Linux (Centos) distributions, you should remove them. Click on the distribution, and for each partition, select the partition and click the remove button (minus sign) and confirm deletion.
Remember that the sizes are recorded in MB (eg. 30 GB = 30000 MB) and you should multiply GB by a factor of 1024 to get the correct size. (eg. 30 GB x 1024 = 30720 MB)

  1. We will now create some mount points under the root (/) partition. Click on the add button (plus) sign.
  2. In the Add a New Mount Point, click the drop-down button and select /boot/efi (or /boot if /boot/efi is not present) for the mount point and type 2954 as the desired capacity, and then click Add mount point.
  3. When you return to the main screen, make certain that this mount point is a Standard Partition and not LVM.
  4. Add another mount point, but in the Add a New Mount Point screen, select / as the mount-point (either by typing or selecting from drop-down menu), and enter 30720 in for partition size and click Add Mount Point button.
  5. You will return to the previous dialog box.
    For the / partition, change the file-system type from xfs to ext4 and make certain that the Device Type is set to LVM.
  6. Repeat the same steps above for the /home partition (calculate the equivalent size for 40GB (ext4 file-system type and LVM as device type).
  7. Add a mount point /var/lib/libvirt/images (type yourself, check spelling!) for size 100GB (file-system type ext 4 and device type LVM).
  8. Recheck each of the created partitions, and make certain that the file-system type is set to ext4 and the Device Type should be LVM.
  9. Finally, add a swap partition (Mount Point: swap) for 16 GB.
  10. Check that your partition settings are correct (you can ask your instructor or lab monitor to confirm), and then click Done (possibly twice) in order to proceed

  11. A Summary of Changes screen will appear to show the partitioning operations that will be created. Click the Accept Changes and click Begin Installation in the Installation Summary screen to proceed with the installation.

Part 3: Completing the Installation

This screen indicates that installation is complete. You should remove the install DVD and confirm Centos7 boots from your removable hard drive.
Perform the Following Steps:
  1. During the installation process, you will required to create a root password (for administration access) and create a regular user account. Click on Root Password and enter your root password. Think of an appropriate password and record that password somewhere in case you forget! An indicator will appear to show you how secure your password is. Retype your root password and click Done (you may have to click Done twice if your password is not considered to be a strong password).
  2. You need to create a regular user account. This account will be used to graphical log into your host machine. It is never recommended to graphically log into a graphical Linux/Unix system as root. It is better to log into a regular user account, then run a command to login as root (you will learn how to do this later in this lab).
  3. Click User Creation and enter your full name, username, and an appropriate password (and confirm password). Click Done to finish (click twice if password is not considered to be a strong password).



Important.png
Keep the root password the same for Host and VMs
In order to simplify running the lab checking scripts in future labs, using the same root password for ALL machines (c7host and virtual machines). Also use the same username and passwords for all of your machines (c7host and virtual machines). Do not do this in a production environment!


  1. When installation is complete, you will notice a message at the bottom of the screen stating: CentOS is now successfully installed and ready for you to use!
  2. Click the Reboot button. Your DVD will briefly open in the DVD drive bay. Make certain to remove this installation DVD so that Centos will boot from your hard drive.
  3. After the system reboots, a boot menu should briefly appear, then prompt the user to accept the License Information (this is only a one-time occurrence).
    In order to accept the license agreement, Click on License Not Accepted and graphically accept the license and then click FINISH CONFIGURATION to finish the installation process.

    NOTE: If you have an older version of Centos7, you must perform the alternative steps:
    Issue the following keystrokes:

    1 followed by ENTER (to select the license agreement prompt
    2 followed by ENTER (to accept the license agreement)
    c followed by ENTER (to save the selection)
    c followed by ENTER (a second time to continue booting into the system)

  4. The system should then graphically prompt the user to login with their regular user account. Click on your regular user account name and enter your regular user password.

  5. The last phase of the installation process should now run:
    • Confirm English as the default input source and click Next.
    • Skip the creation of online accounts by clicking Next.
    • Start using your installed Linux system by clicking Start Using CentOS Linux.

  6. Open a web-browser and check to see if you can connect to the Internet. It is essential that your Host machine can connect to the Internet in order to download checking scripts, installing software and performing software updates.
Important.png
Can't connect to Internet on your Host Machine with Removable Hard Drive
Sometimes, you may not be able to connect to the Internet when booting your Host machine from your removable hard disk drive. If that is the case, you should notice on the top right hand side of your desktop two square brackets containing dots. To fix that problem, you need to perform the following steps to temporarily place your NIC card into hibernation:

  1. Quickly press the power button (do not hold it down!). This should put it in suspend mode. You can confirm it is in suspend mode if the blue power light is flashing.</ li>
  2. Wait a few seconds, then press the power button again. This will go out of suspend mode. You can confirm is is not in suspend mode if blue power light is solid (not flashing).
  3. In a few seconds, the symbol on the top right-hand side should appear like a solid box (it means that you can now connect to the Internet).</div>



Answer Investigation 1 observations (all parts and questions) in your lab log book.

INVESTIGATION 2: COMMON POST-INSTALL TASKS

Part 1: Turning Off Locked Screen-saver

Your system automatically enables a screen-saver application which is a useful security tool to prevent unauthorized viewing of information on a terminal after a certain amount of inactivity. Turning-off the locked screen-saver for this (and other) virtual machine can be useful when waiting for your instructor to come over to "sign-off" your computer lab without having to re-issue user passwords.

To Disable the Locked Screen-saver, Perform the following steps:

  1. Click on the power button at the top right-hand corner of the window.
  2. Click the Settings icon (bottom left-hand side of menu - looks like a screw-driver and wrench icon.
  3. Click the Power icon located in the Settings Dialog Box
  4. Change the amount of time in the Power Saving section to Never or a longer period of time
  5. Close the Settings Dialog box.


Part 2: Accessing Administrative Privileges

Note.png
Accessing the Administration Account (root)
Many administrative tasks require the root administrative account. There are many ways to access this administration account:
  • Login: root (enter root password)
  • Switch User to root (without login):
    • su: Remains in regular user's directory, does not run root's startup script(s).
    • su - : Changes to root's home directory (/root) and runs root's start script(s).
Perform the following steps:
  1. Refer to the Information box regarding how to access the admin account from the command line.
  2. Issue the command su Issue the pwd and whoami commands to confirm your directory pathname. When finished logout of this account.
  3. Issue the command su - Issue the pwd and whoami commands to confirm your directory pathname. What do you notice are the main differences between using su versus using su - ?
  4. An installation log file called /var/log/anaconda/packaging.log has been created to record the installation of your c7host machine. This file is an ASCII file which can be viewed with the more command.
  5. You can make use of this file to determine how many packages have been installed: complete the following command to count the number of packages that are labelled "Installing" in the installation log file:
grep -i packaging /var/log/anaconda/packaging.log | wc -l


Part 3: Disable SELinux and Perform Software Updates

Important.png
Never disable SELinux in the real world
It is highly discouraged and unsafe to disable SELinux on a public-facing server. Some applications may require tedious steps to setup SELinux rules. Disabling SELinux is never the correct way to solve an issue.

SELinux stands for Security-Enhanced Linux. It is a component that helps to better secure the system to protect against intrusion (hackers). SELinux is enabled upon the default install of CentOS. SELinux can be a good thing, if you take care of it and know how it works. For this course it is strongly recommended that you disable SELinux by default because we won't have the time to reconfigure it every time the labs make it necessary.

Perform the following Steps:
  1. Disabling SELinux is quite simple.
  2. Edit the file /etc/selinux/config
  3. In the editing session, set SELINUX to disabled (from enforcing) and save your editing session.

Answer Investigation 2 observations (all parts and questions) in your lab log book.

Part 4: Using Shell Scripting to Generate System Information Reports

Note.png
Bash Shell Scripting Reference Guide:

She-bang Line
  • Forces shell script to run in a specific Shell
  • Must be at beginning of first line (eg. #!/bin/bash)

Variables
Environment
  • System-wide or "global" variable
  • Usually appear in UPPERCASE letters
  • Can view with command: set | more
  • $ in front to expand variable to value
  • Examples: USER, PATH, HOME, SHELL
User-defined
  • Variable created by user (command line, scripting)
  • Examples:
    myVar="my value"; readonly myVar; export myVar
    read -p "enter value: " myVar
Positional parameters
  • Assign values with set command or shell script arguments
  • These variables are numbered (eg. $1, $2 ... $10}
  • Special parameters: $*, $@, $#, $$, $?
Command Substitution
  • Useful method to expand output from a command to be used as an argument for another command.
  • Examples:
    file $(ls)
    set $(ls);echo $#;echo $*
    echo "hostname: $(hostname)"

if / elif / else statements
  • If a command runs (even pipeline command like to grep to match) will be true (0); otherwise, false (non-zero), thus can use with logic statements.
    • Example:
    if echo $myVar | grep "match"
    then
    echo "Match"
    fi
  • The test command is used to test conditions. Square brackets [ ] is short-cut for test command (args contained inside with spaces). The exit command can be used to terminate the shell script with a false value.
    Example:
    if [ $USER = "root" ]
    then
     echo "You must be root"
     exit1
    fi
  • For numberic comparison, use the test options: -gt,-ge, -lt, -le, -eq, -ne
    Example:
    if [ $grade -gt 79 ]
    then
     echo "You get Good Mark"
    elif [ $grade -gt 49 ]
    then
     echo "You pass"
    else
     echo "You fail"
    fi
  • For testing for file information, you can use -d to test if directory pathname exists, and -f if the file pathname exists. You can use ! for negation.
    Examples:
    if [ -d directory-pathname ]
    then
    echo "directory exists"
    fi

    if [ ! - f file-pathname ]
    then
    echo "File does not exist"
    fi


It is very common for System Administrators to keep records regarding their installed computer systems. For example, it is necessary to have a record of all the hardware information for each machine in order to help fix computer hardware problems, and to assist when purchasing additional consistent computer hardware.

Therefore, it makes sense to also have a record of the installed computer software as well. This can contain information regarding the Linux operating system, installed software, and network connectivity information.


Perform the Following Steps:
  1. Study the Linux commands and their purpose to note computer software information for your installed c7hostVM. You should take time to issue each of these commands to view the output, and record this chart in your lab1 logbook.

  2. Login to your c7hostVM, open a Bash Shell terminal, and login as root by issuing the command:
    su -

  3. Make certain to record output from these commands (except for the ps -ef output) in your lab1 logbook.


Linux/Unix System Information Utilities
Command(s) Purpose
uname -rv
hostname
ps -ef		 Basic Linux OS information such as kernel version, host-name of Linux server, and all processes that are running on the system after installation.
rpm -q -a | wc -l
rpm -q -a -l | wc -l
rpm -q -l gedit | wc -l		 Obtain number of installed packages in the rpm database. Option -q is to "query" informationo, option -a means for all installed packages, option -l means all files installed as opposed to just the application.
ifconfig
route -n
nslookup (at prompt, enter command: server) 		Obtain network connectivity confirmation including: IP ADDRESS, Netmask, routing (default gateway), and the default Domain Name Server.


You may have learned about creating and running Bash Shell Scripts in your ULI101 course. Shell scripts help Linux users and system administrators to automate repetitive tasks to become more efficient and to help them save time. You will be reviewing and building a basic Bash Shell script to generate information reports for your newly-installed Linux host machine.


  1. Refer to the Bash Shell Scripting Reference Guide on the right-hand side prior to proceeding with this section. As you continue, you are required to make Bash Shell scripting notes in your lab1 logbook.
  2. Create a directory called bin in your root home directory to store your shell scripts by issuing the command:
    mkdir /root/bin
  3. Change to that newly-created bin directory


NOTE: Although it is possible to copy and paste, is it highly recommended to manually enter the following Bash Shell scripting content to become familiar with writing Bash Shell scripting code. Remember: you will be required to create a Bash Shell script on your final exam, so you need the practice!


  1. Launch a text editor (such as vi or nano) to create a Bash Shell script called: myreport.bash in your current directory.
  2. Copy and paste the text below into your vi editing session for your file report.bash
    (how do you copy and paste efficiently in Linux?)


#!/bin/bash

# Author: *** INSERT YOUR NAME ***
# Date: *** CURRENT DATE ***
#
# Purpose: Creates system info report
#
# USAGE: ./myreport.bash

if [ $USER != "root" ] # only runs if logged in as root
then
 echo "You must be logged in as root." >&2
 exit 1
fi

  1. Save your editing session, assign the myreport.bash file read and execute permissions (at least for the owner) and run by typing:
    ./myreport.bash
  2. Did it work?
  3. Reopen your text-editing session for /root/bin/myreport.bash and add the following lines of code to the bottom of the shell script file:


# Create report title

echo "SYSTEM REPORT" > /root/report.txt
echo "Date: $(date +'%A %B %d, %Y (%H:%M:%p)')" >> /root/report.txt
echo >> /root/report.txt

  1. Save and run the bash shell script. View the contents of the file called report.txt that was generated (I hope you are using the up arrow key to issue previously issued commands in order to save time!). Notice how the redirection symbol > is used at the beginning of the report, and then the other redirection symbol >> is used to help "grow" the report with the other content.
  2. The only remaining content of the report would be the system information. We can use a shell scripting trick called "command substitution" $( .. ) in order place results from an command to be used by another command (like echo). Re-edit the shell script and add the following code at the bottom of the shell script file:


echo >> /root/report.txt
echo "Hostname: $(hostname)" >> /root/report.txt
echo >> /root/report.txt
echo "Kernel Version: $(uname -rv)" >> /root/report.txt
echo >> /root/report.txt

  1. Save, run the script, and view the report.txt contents (are you using tip that was given to save time?).
  2. Edit the shell script and include output from the ps aux and ifconfig commands (with appropriate titles). Remember to redirect that output to add to the bottom of the file!
  3. Save, run and confirm that the shell script is working correctly.
  4. What would be the use of keeping this shell script as a Linux system administrator?
  1. Here are some more "complex" Bash Shell scripts, that perform the same task. Although you are not require to understand some of these other tricks, it is recommended that you view the contents of the scripts and save them for future consideration or exmaples.
  2. The wget command can be used to quickly download files from the Internet. Issue the following command:
    wget https://scs.senecac.on.ca/~murray.saul/text-report.bash
  3. Verify that the file text-report.bash was downloaded to your current directory.
  4. Assign read and execute permissions for this file by issuing the command: chmod u+rx text-report.bash
  5. Run this Bash Shell script by issuing the command: ./text-report.bash
  6. Check to see if it created a report in your current directory. What is the purpose of the report?
  7. Use the vi text editor to view the contents of the file text-report.bash. Can you understand how this script works?

  8. Use the wget command to download, study, and run the following shell scripts on-line:
    https://scs.senecac.on.ca/~murray.saul/report.bash
     https://scs.senecac.on.ca/~murray.saul/report3.bash

  9. Try to understand what these Bash Shell scripts do.
  10. You have completed lab1. Proceed to Completing The Lab, and follow the instructions for "lab sign-off".

Answer Investigation 2 observations (all parts and questions) in your lab log book.


LAB 1 SIGN-OFF (SHOW INSTRUCTOR)

Students should be prepared with all required commands (system information) displayed in a terminal (or multiple terminals) prior to calling the instructor for signoff.


Shell scripting is so essential for Linux administration that this course has created a shell script for every lab for this course that a student must download and run in order to check their work.

If you have performed the lab correctly, then you will get a series of  OK  messages and you can proceed with the SIGN-OFF for lab1. On the other hand, if there were errors, then a  WARNING  message will appear with general suggestions that you will need to fix on your c7hostVM in order to have your OPS235 sign-off in this lab in order to proceed to the next lab.

Perform the Following Steps:
  1. Make certain that your c7host VM is running, open the Bash Shell terminal and issue the command: su - and enter root's password.

  2. Change to the /root/bin directory.

  3. Download the checking script by issuing the following Linux command:
    wget http://matrix.senecac.on.ca/~murray.saul/ops235/lab1-check.bash

  4. Give that downloaded shell script file execute permissions (for the file owner).

    FYI: Your this checking script will not work unless you issued "su -" instead of just "su".

  5. Run the shell script and if any warnings, make fixes and re-run shell script until you receive "congratulations" message.

  6. Arrange evidence (command output) for each of these items on your screen, then ask your instructor to review them and sign off on the lab's completion:
✓ Output of lsblk command showing correct partition names and sizes
✓ Run the lab1-check.bash script in front of your instructor (must have all  OK  messages)
✓ Lab1 logbook containing the values for:
  • IP address, MAC address, Default route (gateway) and
    DNS name server IP Address

Practice For Quizzes, Tests, Midterm & Final Exam

  1. Why do you need to create a host machine before using a virtual machine?
  2. List the major screens (steps) in the installation of Centos7 full install DVD.
  3. List the steps for disabling SELinux.
  4. List 2 ways that you can access your root account
  5. What is the difference between the commands su and su -  ?
  6. What is the home directory for the user "root"?
  7. How do you determine the host name of your GNU/Linux workstation?
  8. What command can display the NIC's MAC address?
  9. What command is used to get a list of running processes on your newly-installed system?
  10. Write the Linux command to download the on-line file: http://linux.server.org/package.tar.gz
  11. Write a Bash Shell Script to prompt the user for a directory, and then display the file types for all files in that specified directory (hint: use the read command and then use the file command and command substitution with the ls command). Test the Bash Shell script by adding execute permissions and run the Bash Shell Script.
  12. Modify the previously created shell script to perform error checking after prompting for a directory to test if the specified directory does not exist. If it does NOT exist (i.e. true), display an error message indicating that the directory does NOT exist, and issue the command exit 1 to terminate the Bash Shell Script. Test the Bash Shell script by adding execute permissions and run the Bash Shell Script.
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