OPS235 Lab 4 - Fedora17

Working with Partitions / User & Group Management

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 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. Learn about partitions, and how to create and format them without using LVM
2. Identify and define major entries in the /etc/passwd, /etc/shadow, and /etc/group files.
3. Learn how to add and remove and modify user accounts.
4. Learn how to create and manage groups.

Required Materials (Bring to All Labs)

• Fedora 17 LIVE CD
• Fedora 17 x86_64 Installation DVD
• SATA Hard Disk (in removable disk tray)
• USB Memory Stick
• Lab Logbook

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):

Partition/Filesystem Management Utilities:	User/Group Management:
fdisk cfdisk mkfs.ext3 mount umount	/etc/passwd File /etc/skel File /etc/group File useradd userdel usermod groupadd groupdel chmod

Resources on the web

Additional links to tutorials and HOWTOs:

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

Creating / Formatting / Mounting Partitions

Investigation 1: Create partition (Graphical Method)

Perform this investigation on fedora1 and fedora2

1. Make sure that on both virtual machines you have system-config-lvm and gparted installed. If you finished lab3 - you should have system-config-lvm on fedora2, but you still have to install it on fedora1.
2. In the end of the last lab we used the graphical tool system-config-lvm to create a logical volume lv_archive. Examine the logical and physical volumes on fedora2 using system-config-lvm.
3. Run gparted. Gparted will only list traditional partitions, not any LVM information. Note that in Gparted there is a dropdown box for the drive currently displayed. Look for common elements that are displayed in both programs.
4. Just as we added a new physical drive to fedora3 in lab3 - go to the hardware details (in the virtual-manager application) in fedora1 and add a new hard disk of 2GBs, make sure it's a VirtIO disk.
5. Instead of adding it to the volume group for use with LVM we're going to create a traditional partition on it, and a filesystem on that partition:
   1. Run gparted on fedora1 and select the new drive, if you added it correctly it should be /dev/vdb.
   2. Create a new partition using up all the space (approx. 2GB) with an ext4 filesystem, with the label archive. Don't call it lv_archive since it's not a logical volume.
   3. Gparted may not allow you to create a partition because the drive has not been initialized. Create a partition table as the tool tells you to do, then create the partition.
   4. When you're ready to apply the changes - click the "Apply all operations" button.
6. Run system-config-lvm on fedora1. Do you see the archive partition you created?
7. Go back to gparted and shrink the /dev/vdb1 partition to be 1GB in size. Don't forget to apply the changes.
8. Spend some time looking at the drive/partition/physical volume/logical volume details in gparted and system-config-lvm on fedora1 and fedora2 - by the end of this lab you should be able to explain everything in all of the views for these applications.

You need to be comfortable with these concepts on tests - make useful notes in your lab log book.

Investigation 2: Create partition (command-line method)

Perform this investigation on fedora1.

1. There are two command-line programs that can be used for working with partitions on linux: fdisk (something rather unique) and cfdisk (something like the old DOS fdisk, if that means anything to you). cfdisk is easier to use, but fdisk is available on more systems by default. You can choose either tool for completing this investigation.
2. Give the full path to the hard drive device (vdb) as the first parameter to fdisk. If you don't understand what this means - you may want to do a review of some parts of ULI101.
3. Create a new primary partition on the drive, using up all the available free (unpartitioned) space. Tip: in fdisk use the 'h' command to get a list of all available commands.
4. Don't forget to save your changes.
5. Now we have a partition /dev/vdb2. But there is no filesystem on this partition yet. We need to create a filesystem (both system-config-lvm and gparted did the following step automatically): mkfs.ext4 /dev/vdb2 -L archive2
6. Run gparted again, look for the changes that happened after you created the partition/filesystem.

Will you remember how to use fdisk or cfdisk and mkfs? Make notes in your lab log book.

Investigation 3: Manually Mounting / Unmounting Filesystems

Perform this investigation on the VM named fedora1.

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. Issue the command called mount . This command provides information relating to various partitions (logical volumes) and corresponding "mount points" (directories).
2. Record the information from issuing the mount command for lv_root. Can you write the command that will quickly find just the line you're interested in from all the output of the mount command? You need to know this (from ULI101).
3. Create the directories /archive and /archive2
4. Issue the commands mount /dev/vdb1 /archive and mount /dev/vdb2 /archive2. Did anything happen? Issue the mount command again. Is there any difference with the command output?
5. Copy some files to /archive and /archive2, then unmount the two partitions. After the unmount is successful - look at the two directories. Where did your files go?
6. Note that CD/DVD disks also need to be mounted for you to access files on them. Try mounting a DVD manually (without using the GUI) on our host - you'll need to use the mount command, and know the device name of your drive (it's probably /dev/sr0).

Do you know how to use the mount/umount commands? Make notes in your lab log book.

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

Perform this investigation on fedora1.

1. Check the man page for /etc/fstab by entering the command man fstab
2. Edit your /etc/fstab file to mount the partitions /dev/vdb1 and /dev/vdb2 to /archive and /archive2
3. Issue this command:

mount -a

5. What does that command do?
6. Confirm that the partitions mounted.
7. Issue a command to list the contents of /archive and /archive2. Are there any files?
8. Reboot the fedora1 VM, and verify that /archive and /archive2 have now been automatically mounted.

Make notes about the format of the lines in fstab in your lab log book.

User/Group Management

Investigation 5: The /etc/passwd file

Perform this investigation on the VM named fedora1.

1. Read about the file: http://linux.die.net/man/5/passwd
2. Now look at the contents of the /etc/passwd file.
3. Make note of the contents of that file, and make certain and record in your lab log-book the information that each field contains.
4. Why do you think there are so many users?
5. Look at the names of the users. What do you think these user names represent? Are they people?
6. What is the numeric user ID (UID) of the root user?
7. 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

Perform this investigation on the VM named fedora1.

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. Use the grep command to obtain information for each of the newly created users within the /etc/passwd file.
   • 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.
   • What is the purpose of the /etc/shadow file?
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. Boot-up your fedora3 VM.
8. Create a new user using your Matrix account user-name.
9. Issue a command to verify that you have created this user account.

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
   1. Which values of GID are reserved for system accounts?
   2. Which values of GID are reserved for non-system user accounts?
   3. What is the lowest available GID number for non-system users?
   4. What is the default group name of a new user?
   5. Add a new group named ops235 with a GID of 600.
   6. 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 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

Perform this investigation on the VM named fedora1.

1. Read the man page for the usermod command. Note which options change the user's full name, primary group, supplementary groups, and shell.
2. Add each of your new pod mate accounts to the group ops235 (in other words, add ops235 to each user as a supplementary group).
3. Examine /etc/group. What has changed?
4. Experiment with your pod-mate accounts to share and deny access to same group members by creating directories and files, and use the chmod command. How is the /etc/group related to file sharing permissions?
5. 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?
6. Just for interest, how would you use a graphical utility to modify user account information?
7. Be sure to record your observations in your lab notes.

Shutdown VMs
It is time to safely shut-down all of your Virtual Machines. Please proceed to Completing the Lab

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. Graphical or command-line view of the two new partitions in fedora1.
2. /etc/fstab entry in fedora1 VM to automatically mount /archive and /archive2
3. Evidence that /archive and /archive2 are currently mounted.
4. Proof of ops235 group entry in /etc/group in fedora1 VM
5. Proof of pod-mate user account information in /etc/passwd in fedora1 VM.
6. Proof of new VM backups.

Preparing for Quizzes

1. What is the reason to extend a Volume Group?
2. What is the purpose of the file called /etc/fstab?
3. How do you ensure that a file-system is mounted every time that a system is started?
4. What are the purposes of the following files: /etc/passwd, /etc/shadow, /etc/group?
5. Explain the purpose of the /etc/skel directory.
6. What do the terms UID and GID represent. What is their purpose?
7. List the steps to create a user account on a system.
8. List the steps to change user account information on a system.
9. List the steps in order for users to share file and directory accounts as "same group members".
10. List the steps to remove a user account. What is required to remove a user account's home directory as well?