OPS235 Lab 4 - Fedora17

This is a draft only!
It is still under construction and content may change. Do not rely on this information.

Introduction

• In this lab, you are going to learn how to create and format partitions. You will be creating partitions by using both graphical and command-line using LVM and other Linux utilities.

• Also in this lab, you will learn how to manage (add, delete, modify) user accounts on your Fedora systems. You will also learn how to create and maintain groups to allow users to share and protect data.

Objectives

1. Identify and define major entries in the /etc/passwd, /etc/shadow, and /etc/group files.
2. Learn about partitions, and how to add "virtual partitions with LVM.
3. Learn how to create a "virtual partition" in a Virtual Machine.
4. Learn how to add and remove and modify user accounts.
5. Learn how to create and manage groups.

Required Materials (Bring to All Labs)

• Fedora 16 LIVE CD - You can burn this onto a CD-R in the Open Lab
• Fedora 16 x_64 Installation DVD - You can burn this onto a DVD-R in the Open Lab (or burn image onto a DVD+R if you are using the Freedom Toaster).
• SATA Hard Disk (in removable disk tray)
• USB Memory Stick (minimum 64M)
• Lab Logbook (Lab4 Reference Sheet) (to make notes and observations).

Prerequisites

• Completion and Instructor "Sign-off" of Lab 3: OPS235 Lab 3

Linux Command Online Reference

Each Link below displays online manpages for each command (via http://linuxmanpages.com):

LVM Management Utilities:	User / Group Management:
vgs lvs pvs fdisk lvextend lvcreate pvcreate vgextend mount umount	/etc/passwd File /etc/skel File /etc/group File useradd userdel usermod groupadd groupdel

Resources on the web

Additional links to tutorials and HOWTOs:

• Logical Volume Management
• Partitioning with fdisk
• Mounting / Unmounting File-systems
• UID and GID explained

Creating / Formatting / Mounting Partitions

Do not Shut-Down VMs Until Instructed
You will be running all 3 VMs eventually when performing this tutorial, Leave all VMs running until you are instructed to shut them down at the end of this lab.

Investigation 1: How to Add a PV to an existing VG (Graphical Method)

Perform this investigation on the VM named fedora1.

In this investigation we will be adding an additional 2 GB virtual disk to our fedora1 system, and use it as an additional physical volume...

1. Start virt-manager.
2. Shutdown fedora1 if it is running.
3. Open the console window for fedora1.
4. Select the menu option View>Details.
5. Click Add Hardware button at the bottom left-hand corner.
6. Make certain to remain in the default section called "Storage".
7. Make the following selections in this "Storage" dialog box:

• Under Create a disk image on the Computer's Hard Drive, change the size to 2 GB.
• Click on Select Managed or Other Existing Storage. You can specify a file pathname for the Hard Drive (refer to diagram). If no file pathname is provided, then the system will assign a name in the directory /var/lib/libvirt/images/.
• Select Device Type: Virtio Disk
• Select Storage Format: raw
• Click FINISH to proceed.

8. Boot the system. You should now have both /dev/vda and /dev/vdb.
9. Record the size of the volume group and the amount of free space (Hint: use a command that you learned in a previous lab).
10. Refer to the following tutorial to use the fdisk command: :* Partitioning with fdisk
11. Use the fdisk command to create a primary partition for /dev/vdb with a single partition (number 1) that fills the whole disk.
12. Check the messages printed when fdisk exits -- you may need to reboot the system in order for the new partition table to take effect.
13. Run this command to format the physical volume: pvcreate /dev/vdb1
14. Add the new physical volume to the existing volume group: vgextend nameOfVolumeGroup /dev/vdb1
15. Verify that the volume group is larger and has more free space.

Answer the Investigation 1 observations / questions in your lab log book.

Investigation 2: How to Add a PV to an existing VG (Command Line Method)

Perform this investigation on the VM named fedora3.

1. You are going to repeat the same steps as outlined in Investigation #1, but on your fedora3 system via command line.
2. Make reference to the following command line resource: Logical Volume Management

• (Hint: First view section on Adding a Physical Volume. Also, write down the commands first and check prior to issuing them in sequence.)

3. Verify that the volume group is larger and has more free space from the series of commands that you issued.

Answer the Investigation 2 observations / questions in your lab log book.

Investigation 3: Manually Mounting / Unmounting Partitions

Perform this investigation on the VM named fedora2.

So far, we have simply assumed that when the Fedora OS boots-up, that its file-system is automatically available. In this investigation, you will learn how file-systems (or portions of file-systems) can be mounted or "connected" to existing file-systems. You will also learn how to unmount (or "disconnect") portions of file-systems from existing file-systems.

1. Open a terminal and login as root.
2. Issue the command called mount . This command provides information relating to various partitions (logical volumes) and corresponding "mount points" (directories).
3. Record all of the information for the "mount" command in your Lab log-book.
4. Issue the command umount /archive , then issue the mount command. What is different in the command output?
5. View the online man pages for the mount command. Using the information that you recorded in your Lab logbook for step #3, issue the mount command to "re-connect" the lv_archive directory to your existing fedora2's file-system (refer to the section "Linux Command Online Reference" above).

File-System Type Option No Longer Required for Mount Command
When viewing examples online, you may notice that the -t option is used with the mount command to indicate the version or type of file-system to mount.
The -t option is no longer required for the mount command,

6. Explain how the mount command would be useful for Linux system administration.

Answer the Investigation 3 observations / questions in your lab log book.

Investigation 4: How Partitions are Automatically Mounted Upon Boot-up

Perform this investigation on the VM named fedora2.

1. Create a directory called /storage (i.e. lab5 is a subdirectory of the root directory)
2. Check the man page for /etc/fstab by entering the command man fstab
3. Edit your /etc/fstab file to mount the partition /dev/sda2 to /storage
4. Issue this command:

mount -a

5. What does that command do?
6. Confirm that the partition mounted and copy some files to it.
7. Reboot the fedora2 VM, and verify that /storage has been automatically mounted.
8. In the previous investigation, we mounted the directory as /archive, but in this investigation we automatically mounted it as /storage. What purpose does could this server for a Linux system administrator?

Answer the Investigation 4 observations / questions in your lab log book.

User/Group Management

Investigation 5: The /etc/passwd file

1. Look at the /etc/passwd file.
2. Make note of the contents of that file.
3. Read about the file: http://linux.die.net/man/5/passwd
4. Make sure you know what information each field contains.
5. Why do you think there are so many users?
6. Look at the names of the users. What do you think these user names represent? Are they people?
7. What is the numeric user ID (UID) of the root user?
8. The user IDs of real users (people) are different from the user IDs of system accounts. What is the pattern?

Answer the Investigation 5 observations / questions in your lab log book.

Investigation 6: Adding users

Use f16host
Perform these steps in the f16host system. Due to a configuration issue, these steps may not work normally in the fedora1 virtual host (previous versions of this lab used fedora1 for this investigation).

1. Read the man page for the useradd command.
2. Create a new user account for each of your pod mates, using their learn account name as a user name. Give each user a password.
3. Grep the /etc/passwd file for each of the new users.
   • What is the home directory of each user?
   • What group is each user in?
   • What else do you know about each user?
   • Where are the passwords stored?
4. Look at the man page for /etc/shadow using the command man 5 shadow
   • Grep the /etc/shadow file for each of the new users.
   • Make note of this information.
5. Create two new dummy users, ops235_1 and ops235_2.
6. Investigate the home directory of one of your new users.
   • What files are there? Be sure to include hidden files.
   • What do you think these files are used for ?
   • How does the operating system determine which files are created in a new home account? The answer can be found here: http://www.linuxhowtos.org/Tips%20and%20Tricks/using_skel.htm
   • Look at the files (including hidden files) in the template directory referred to in the article. Compare them to what is in a home directory for a new user. What do you notice?
   • Create a new file in this directory with the following command: touch foo
   • Create a new user named foobar, with the option to automatically create a home directory.
   • Look at the contents of foobar's home directory. What do you notice?
7. Be sure to record your observations in your lab notes.

Use fedora3
Perform these steps in the fedora3 virtual machine.

1. Add your matrix account user to fedora3.

Answer the Investigation 6 observations / questions in your lab log book.

Investigation 7: Managing Groups

Use fedora1
Perform these steps in the fedora1 virtual machine.

1. Read the man page for the groupadd and groupdel commands.
2. Note which option allows you to set the Group ID number (GID) when you create a new group.
3. Examine the file /etc/group
   • Which values of GID are reserved for system accounts?
   • Which values of GID are reserved for non-system user accounts?
4. 8 What is the lowest available GID number for non-system users?
   • What is the default group name of a new user?
   • Add a new group named ops235 with a GID of 600.
   • You are angry at some irresponsible users on your system.
     • Add a new group named idiots.
     • Look at /etc/group and note the GID of idiots.
     • What GID is given to a new group if if you do not specify it?
     • Your anger has subsided. Delete the idiots group.
     • Look at /etc/group again and note the change.

Be sure to record your observations in your lab notes.

Answer the Investigation 7 observations / questions in your lab log book.

Investigation 8: Deleting users

Use fedora1
Perform these steps in the fedora1 virtual machine.

1. Read the man page for the userdel command. Note which option automatically removes the users home directory when that user is deleted.

1. Delete the user ops235_1 using the command userdel ops235_1
2. Delete the user ops235_2 using the same command with the option which removes the home directory of the user.
3. Check the contents of the /home directory. What do you notice?
4. Check the contents of the /etc/group directory. What do you notice?

Answer the Investigation 8 observations / questions in your lab log book.

Investigation 9: Modifying users

Use fedora1
Perform these steps in the fedora1 virtual machine.

1. Read the man page for the usermod command. Note which options change the user's full name, primary group, supplementary groups, and shell.

1. Add each of your new users to the group ops235 (in other words, add ops235 to each user as a supplementary group).
2. Examine /etc/group. What has changed?
3. Use the usermod command to associate each of your pod mates' full name to their user name, as shown in your text. With each change, examine their entries in the /etc/passwd file. What has changed?
4. Be sure to record your observations in your lab notes.

Answer the Investigation 9 observations / questions in your lab log book.

Completing the lab

Time for a new backup!
If you have successfully completed this lab, make a new backup of your virtual machines. Remember to also make a backup of the new second virtual disk drive on fedora1 -- you now have two virtual disks on fedora1, and therefore two image files, and therefore will need two backup files.

Arrange proof of the following on the screen:

1. Account created on fedora3 matching your Matrix account.

Preparing for the Quizzes

1. What is the purpose of /etc/fstab?
2. What did you have to do in order to move the home directories onto a new filesystem? Why?