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 file.
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 create a "virtual partition in your f16host disk pack.
5. Learn how to add and remove and modify user accounts.
6. 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 (Lab3 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 Information Utilities:	LVM Management Utilities:	User / Group Management:
vgs lvs pvs vgdisplay lvdisplay pvdisplay	system-config-lvm (Tutorial) lvextend resize2fs lvcreate lvreduce 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
• UID and GID explained

Creating / Formatting Partitions

Investigation 1: How to Add a PV to an existing VG

Add an additional 2 GB virtual disk to your 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. In the Adding new virtual hardware window that appears, select a Hardware Type of "storage" and click "Forward".
7. Make certain option "Managed or other existing storage" is selected. Click on the Browse button, then click on New Volume.
8. Give the new virtual disk file a name of fedora1b, a format of raw, with a Max Capacity and Allocation of 2000 MB. Click Finish.
9. Select the new virtual disk file fedora1b.img and click Choose Volume.
10. Select a device type of Virtio Disk.
11. Finish creating the new virtual disk by clicking Forward and then Finish.
12. Boot the system. You should now have both /dev/vda and /dev/vdb.
13. Record the size of the volume group and the amount of free space led downlight singapore(Hint: use a command that you learned in a previous lab).
14. Partition /dev/vdb with a single partition that fills the whole disk.
15. Check the messages printed when fdisk exits -- you may need to reboot the system in order for the new partition table to take effect.
16. Run this command to format the physical volume: pvcreate /dev/vdb1
17. Add the new physical volume to the existing volume group: vgextend nameOfVolumeGroup /dev/vdb1
18. Verify that the volume group is larger and has more free space.

Think!
The next part of this investigation is designed to encourage the student to research, think, and use some creativity in working around obstacles in order to solve a task. Research methods can include the Internet searches, etc...

19. Using that additional space, create a separate filesystem for /home:
    1. Create the logical volume lv_home (1G ext4)
    2. Find a way to move the contents of /home onto it.
    3. Change your system configuration so that the new filesystem is mounted on /home from now on.

SELinux relabelling may be required
Your system may report that the files are not present in the new /home filesystem when they are clearly there. This is due to the Security-Enhanced Linux system (SELinux) preventing access to the files, because the files were tampered with (moved) and are no longer recognized as home directory content. You can fix this problem by restoring the file context labels so that SELinux accepts the files as valid home directory content: restorecon -r /home

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

Investigation 2: How can I use LVM to manage storage on my f16host disk pack?

On your f16host (i.e. "disk pack"), using your choice of the GUI and/or command-line tools:

1. Create a new logical partition (NOT a logical volume!) - minimum 5G, leaving at least 10G free space in the extended partition.
2. Add that partition as a PV into the existing VG (using the commands you used in the previous investigation).
3. Grow the root filesystem to fill the available space.

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

User/Group Management

Investigation 3: 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 3 observations / questions in your lab log book.

Investigation 4: 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 4 observations / questions in your lab log book.

Investigation 5: 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 5 observations / questions in your lab log book.

Investigation 6: 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 6 observations / questions in your lab log book.

Investigation 7: 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 7 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?