OPS235 Lab 1 - CentOS6

CentOS Installation (on Main Host - c6host)

Introduction

• In this lab, you are going to install the CentOS (GNU/Linux Distribution) to your removable hard disk from your burned DVD.

• Although this will be a simple install, this CentOS Operating System will be a platform (host) for other Virtual Machine CentOS installations (in future labs). Therefore, it is very important that you take the time to carefully read and perform ALL steps, and take time to check your work.

• After performing the CentOS DVD installation, you will collect baseline information about your system, and perform some post installation configuration to prepare your system for the remainder of the labs.

Objectives

1. Perform a GNU/Linux installation using the CentOS 6.5 distribution
2. Investigate information during and after the CentOS 6.5 installation
3. Perform an update after a recent installation

Required Materials (Bring to All Labs)

• CentOS 6.5 x86_64 Live DVD
• CentOS 6.5 x86_64 Installation DVD1
• SATA Hard Disk (in removable disk tray)
• USB Memory Stick
• Lab Logbook

Prerequisites

• None (First Lab)

Linux Command Online Reference

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

Utilities:

rpm hostname uname ps ifconfig netstat route nslookup wc

Normally you would read man pages on the machine you're working on using the man command, for example man rpm will show you the manual page for the rpm command.

Performing Lab 1

Investigation 1: Performing a CentOS DVD Install on Your Removable Hard Drive

Part 1: Simple Things

1. Insert your removable SATA hard disk into the drive tray.
2. Set your computer's drive selector switch to external (a.k.a position #4).
3. Power up the computer and insert the CentOS 6.5 Installation DVD1 into the DVD drive (refer to main OPS235 WIKI page on how to obtain Installation DVD).
4. Wait until the CentOS DVD boots (could take a few moments).

DVD Boot-up Issues in Seneca's Computer labs
If for some reason, the Installation DVD does not boot:

• Restart the computer, and press the function key F10 to specify the device to boot (eg. DVD drive).
• If the user is prompted for a password, simply press ENTER (without typing any password) at the password prompt.
• Choose the DVD drive from the list of devices avalable for boot.
• You will need to perform this technique to ensure that CentOS boots from the hard drive (in future labs).
• If you have tried this technique, and the CentOS Installation DVD does not boot, you may have to burn a new Installation DVD.

5. Note the time at the beginning of your installation.
6. Select the option Install or upgrade existing system. When the Installation DVD boots, it will prompt the user to test the media (i.e. DVD) for integrity. Since time is limited for installation in the lab, select SKIP. On the other hand, if the install did not work, then you can test out the integrity of the DVD in the computer lab during your spare time.
7. During the install process the user makes selections, then clicks the Next button located at the bottom right-hand portion of the screen to continue. Select the default language (English), the default keyboard layout and Basic Storage Devices in the following installation screens.
8. Set your hostname (name of the computer) to c6host (one word, no space, all lowercase).
9. Set your time zone to Toronto. Note that the system (BIOS) clock is set to local time, not UTC.
10. Root Password: enter a password of your own choosing. Pick one that is hard to guess to protect your system. (Recommendation: use the first letter and all the punctuation from a favorite phrase or song verse. For example, "To be or not to be, that is the question!" could become the password "Tbontb,titq!").

Part 2: Partitioning

You're supposed to use this hard drive only for this course
But if you really need to use it for two courses, and the professor for the other (probably windows) course will allow it - ask your professor for help with partitioning.

1. If you get a warning with something like "This device may contain data" - it's probably your new hard drive and you can safely use it.
2. Select Create Custom Layout, we don't want to use the default setup now. If you are using a hard drive that contains partitions from a previous course (previous version of Linux), delete all partitions prior to proceeding.
3. On your drive you will need the following partitions. These may be primary partitions or logical drives. Remember that the sizes are recorded in MB (eg. 20 GB = 20000 MB). If you have more space than 250GB available - you can add the extra space in equal parts to /home and /var/lib/libvirt/images
   
   Primary Partitions (ext4):
• 20GB for / (i.e. "root")
• 30GB for /home
• 100GB for /var/lib/libvirt/images
  
  Swap Partition:
  
  Swap Partition:
  
  8GB (Note: "swap" must be selected from the drop down menu)
4. Record briefly in your lab logbook what partitions you created of what size and what device names were assigned to them (/dev/sda1, etc.).

Part 3: Completing Installation

1. Select in the next screen the Desktop applications, and in the additional repositories section (at the bottom) accept the default settings, then proceed. You may look at what's available if you choose "Customize now" but you don't need to customize the software installed at this point.
2. Add in your lab logbook a brief description of the term "software repository" and what its major purpose serves (what you think it does). We will not add any existing repositories since we are not currently connected to the Internet. Therefore, we will customize the repositories later.
3. Proceed with the installation. This may take some time. Record in your lab log-book the general steps in the installation process (displayed in the dialog box).
4. When installation is complete, a screen will confirm completion, and ask the user to remove the DVD, and reboot the computer. Write in your lab log-book the time it took to perform this DVD install.
5. Remove the Installation DVD, and click Reboot.
6. When the system starts, set or accept the time and date default.
7. Create a user account for yourself using the same user ID as your learn account, and create a suitable password.
8. Normally, you would want to enable Network Time Protocol, but since we will be experimenting with the networking turned off in later labs, leave it disabled.
9. Finish the post-installation customization and then login to your computer account that you created.
10. Proceed to Investigation 2

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

Investigation 2: How many file packages and files are installed on the system?

For the rest of the tasks in this lab, you must login to your installed CentOS system using your regular user account (not root), open a terminal and execute the following listed Linux commands to obtain information for your lab-logbook (lab1). If you get a Permission Denied message when trying to execute a command, then switch to the superuser account by running the command su - and type in your password for "root" (which you know since you are the main administrator for your system). Once the intended command is executed, type "exit" to exit from the superuser account and return to your regular user account.

Using Superuser Privilege
Throughout this course, you may need to execute commands using the privileges of the the administrative user (username "root", also called the "superuser"). To switch from your account to the root account, type the command: su

After switching user notice and make note of the change in your shell prompt. Also note the difference in output for the whoami andpwd commands.

Whenever this is required, make a note of it, and determine why superuser privilege is required.

When you are finished using the root account type exit to return to your previous account. Avoid using the superuser account unless absolutely necessary, because the superuser account has unlimited privilege and a typo can destroy your system.

In some documentation, you may see the command su - used in place of su. The dash argument causes su to go through the steps that would normally be performed when the root user logs in, including (1) running the startup scripts (such as/etc/profile and /root/.bash_profile and (2) changing to the root user's home directory (/root).

Note that the root user's home directory (/root) is not the same as the root directory of the system (/). It is also in a different directory than the rest of the home directories, which are typically in /home -- the reason for this is that /home is sometimes on a network filesystem shared by another server (as is the case on Matrix), and it's important that the system administrator be able to log in to the system even if the network is not operating normally.

Navigate through your Graphical CentOS system, locate and run a terminal program (in order to issue Linux commands). Issue and record the commands used and the output generated in each of the following steps:

1. The name of the installation log file is /root/install.log -- It is an ASCII file (how can you be sure?) which can be viewed with the less command.
2. 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 ________________ ________________ | wc -l

3. Using the rpm command: you can also use the following commands to list all the installed packages, and the total number of packages installed:

rpm -q -a

rpm -q -a | wc -l

rpm -qa | wc -l

4. The -q option means query, and the -a option means all (in other words, query all installed software packages). Did you get the same number of packages from the above two methods?
5. Some of the files on your system were installed with the software packages, and some were created by system activity (for example, by creating your Learn account and by logging in). If you know the package name (from the install.log), you can list all the files that were installed from the package by using the following command:

rpm -q -l package_name
(where package_name represents the name of the application or package)

6. This combines the -q (query) option with the -l (list filenames) option
7. You can pipe the outupt through wc -l to count the number of lines:

rpm -ql package_name| wc -l

8. Using what you learned in steps 3, 4, and 7, get a count of the total number of files installed by all of the software packages on your system.
9. To find out the name that you have assigned to your Linux system, enter the command: hostname
10. To find out the kernel version of your GNU/Linux workstation and the date it was created, enter the command: uname -rv
11. To find out all the system processes running on your GNU/Linux workstation, enter the command: ps -ef
12. To capture the list of all the system processes to a file called ps.lst, enter the command: ps -ef > ps.lst

Pathname for USB Stick
The default mount location has been changed in linux distributions newer than CentOS. So while we will get /media/usb-device-name, in newer distributions you'll see /run/media/userloginid/usb-device-name

13. Copy the installation log file /root/install.log and the file ps.lst to a USB memory key, or scp to your matrix account as a backup.
14. View the section below to learn about and perform an update on your fresh CentOS install (you may have to find spare time to perform this install if you are running short on lab time). Do not proceed to Investigation 3 without performing an update.
15. The CentOS software is updated frequently to add features, fix bugs, and upgrade security. Perform a system update to get the latest versions of the packages installed: Start the Firefox web browser, turn off popup window blocking (select Edit>Preferences, then select the Content tab and uncheck the box to Block Popups), then login to SeneNET. Open a terminal and type su to start a shell as root. Enter the command yum update This will download and install all of the packages that have been updated since the installation DVD image was created. If you complete this command at Seneca it should run quite fast as Seneca College hosts a CentOS Repository mirror (a copy of all of the current CentOS packages, on a local web server).

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

Investigation 3: What is the network configuration?

Rusty Issuing Linux commands since ULI101?
To be an effective Linux administrator, you need to become comfortable on issuing Linux commands in a shell, and use resources to quickly learn how to properly formulate Linux commands...

You can run the following online tutorials to practice (refresh) issuing Linux commands. These tutorials were designed for another course called "OPS435", but you can still use them for practice. Simply open a shell, SSH into the Matrix server (eg. ssh yourusername@matrix.senecac.on.ca) and run the following 4 tutorials (you can copy and paste these separate pathnames and run like a program):

/home/ops435/tutorials/tutorial1
/home/ops435/tutorials/tutorial2
/home/ops435/tutorials/tutorial3
/home/ops435/tutorials/vi-tutorial

You can also refer to the section above called Linux Command Online Reference to see how use use the following Linux commands to obtain the required information.

1. To check the network configuration settings obtained from the DHCP server, run the following commands, describing the output in your log book:
   • ifconfig
   • route -n
   • nslookup (at the > prompt, enter the word "server" (do not type the quotes) and record the output. Type exit to leave nslookup).
2. Find the following information in the output of the above commands:
   • MAC address of the ethernet network interface
   • Subnet mask
   • The IP address assigned to you by the DHCP server
   • The default gateway
   • The DNS nameserver

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

Investigation 4: SELinux

SELinux
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.

1. Disabling SELinux is quite simple, just edit the file /etc/selinux/config and set SELINUX to disabled.

Completing the Lab

Check off the following items before asking your instructor to check your lab:

• Task 1 - Install Linux Workstation using CentOS
• Task 2 - Collect system information after installation.
• Task 3 - Update CentOS
• Task 4 - Collect network information

Arrange evidence for each of these items on your screen, then ask your instructor to review them and sign off on the lab's completion:

• Can login with your "learn" account name
• Has the package count
• Has correct size partitions for:

• root / (20GB), /home (30GB), swap (8GB)
• /var/lib/libvirt/images (100GB)
• Hint: Can issue lsblk (listblock command)

• Has the correct IP address and MAC address
• Find out the default route (gateway)
• IP of the DNS name server
• Name and contact information on your disk pack
• Lag Logbook (lab1) notes filled-in.

Preparing for Quizzes

1. How many packages were installed?
2. How many files (correct to the nearest hundred) were installed?
3. How many users were created automatically on your system (do not count your learn account)?
4. What is your learn account's UID and GID?
5. What is your learn account's home directory?
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?