OPS235 Lab 5 - CentOS7

Archiving Files, Compiling Software Packages from Source, Managing Services

Overview

• In this lab, you are going to help conserve disk space by learning how to compress and decompress files that are stored on your computer server. In addition, you will learn alternative methods of how to install programs (decompressing zipped tarball archives and then compiling source code).

• In addition, you will learn about how certain processes (services) work, and how the system administrator can manage these services (i.e. turn "on" and "off").

Objectives

1. To create and use archive files (tar and tar.gz)
2. Compiling software packages from source code
3. Install an application from software development repositories using the bit utility
4. Customising file-system start-up

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

• Completion and Instructor "Sign-off" of Lab 4: OPS235 Lab 4 - CentOS6

Linux Command Online Reference

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

Archiving Utilities:	Service Management Utilities:
tar gzip gunzipzip make	chkconfig

Resources on the web

Additional links to tutorials and HOWTOs:

• archiving with tar, gzip, gunzip
• init vs systemd
• init vs systemd vs upstart
• Runlevels

Managing Run-Levels and System Services

Investigation 4: How do we Manage Runlevels?

Use centos2 and centos3
Perform these steps in both of these virtual machines.

The runlevel command is now deprecated in Fedora, and will likely be deprecated in RHEL/CentOS at some point as well, but for now this is what the industry is using.

1. Issue the following Linux command:
   • runlevel
2. Note the difference in output between centos2 and centos3.
3. You can use the init command to change the current runlevel. See a list of runlevels here. Use the man command to learn how to use the init command. Use this command to change the current runlevel in centos2 to 3. What happened? What happens after your reboot?
4. Change the default runlevel on centos2 to 3. What happens now after you reboot?
5. Issue the following Linux command:
   • startx
6. What happens?
7. Log-off your graphical system. You should return to your shell prompt.
8. Change the default runlevel for centos2 back to 5 and reboot to make sure it works.

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

Investigation 5: How do we Manage System Services?

Remain in your centos2 VM
Perform these steps in the centos2 virtual machine.

We have seen that maintaining unneeded packages can be a security risk due to the unnecessary increase in the complexity of your system. Similarly, it is also unnecessarily hazardous, and even more so, to leave unneeded services running. In this investigation, we will learn how to control services, and turn off those services that we think are not necessary to help reduce security risks.}}

1. Issue the following Linux command:
   • service --status-all
2. Note the services that are currently running.
3. Use the service command to stop the service named iptables
4. Issue the service command to verify that this service has stopped.
5. If you reboot now - the iptables service will be turned back on. We don't want it on though, it causes students headaches. To turn it off permanently we need to use the chkconfig command: chkconfig iptables off
6. Reboot and confirm that it's no longer running.

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

Completing the Lab

Arrange evidence for each of these items on your screen, then ask your instructor to check each item:

1. Compressed files: /tmp/archive1.tar.gz and /tmp/archive2.tgz
2. nled application is installed
3. Lab5 notes how to use service/chkconfig commands
4. VMs backed-up

Preparing for Quizzes

1. What is the advantage of disabling services such as bluetooth?
2. What is the difference between a .tgz file and a .tar.gz file? What do these stand for?
3. What is the purpose of a repository?
4. What is source code?
5. How do you build software from source code?
6. Which is preferred: installing from an RPM file, or installing from source code? Why?
7. How do you use service/init/chkconfig to:
   • show/set current runlevel
   • list services
   • stop a service
   • start a service
   • Why is it important to learn how to manage services?
   • Why is it important to stop certain services?

Backup your work
Backup your disk images for centos2 and centos3 Virtual Machines.