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OPS235 Lab 4 - CentOS7

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[[Category:OPS235]]
{{Admon/caution|THIS IS AN OLD VERSION OF THE LAB|'''This is an archived version. Do not use this in your OPS235 course.'''}}
=LAB PREPARATION=
 
==Purpose / Objectives of Lab 4==
{| width="40%" align="right" cellpadding="10"
|- valign="top"
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[[Image:users.png|thumb|right|150px|System administrators are required to add, remove and modify user accounts.]]
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[[Image:on-off.png|thumb|right|135px|In order to perform maintenance, system administrators need to know how to stop and start services for a Linux system. ]]
|}
=Logical Volume Management (Continued) and User / Group Management=
==Introduction==There are many other tasks that a Linux system administrator must perform other than installing Linux and installing software.
In this lab you're going to learn how to:A few additional tasks are user management and managing services.
:* Add a virtual hard disk and expand your vm's existing file system using LVM
:* Administer (add, remove, modify) users on a Linux system.
:* Save time while adding new users using a template of start-up files.
:* Create and manage groups on a Linux system.
== Required Materials <u>Main Objectives</u>:<br>:* Administer '''(Bring to All Labsadd, remove, modify) ==users''' on a Linux system.:* Save time while adding new users using a template of '''start-up files'''.:* Create and manage '''groups''' on a Linux system.:* '''Start and Stop services''' on a Linux system.:* Display the '''status of running services''' on a Linux system.
* 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 2: [[OPS235 Lab 3 - CentOS6]]==Minimum Required Materials==
{|cellpadding="15" width=Linux Command Online Reference==Each Link below displays online manpages for each command (via [http://linuxmanpages.com/ http://linuxmanpages.com]):"40%"
{|width="100%" cellpadding="5"
|'''LVM Information Utilities:'''
|'''LVM Management Utilities:'''
|'''Additional Utilities:'''
|- valign="top"
 |width="10%" |*[http://linuxmanpages.com/man8/vgs.8.php vgs]*[httpImage://linuxmanpagesharddrive.compng|thumb|left|85px|<b>Removable Hard Disk Pack</man8/lvs.8.php lvsb> (SATA)]*[http://linuxmanpages.com/man8/pvs.8.php pvs]*[http://linuxmanpages.com/man8/vgdisplay.8.php vgdisplay]*|width="10%" |[http://linuxmanpages.com/man8/lvdisplay.8.php lvdisplay]*[httpImage://linuxmanpagesubs-key.com/man8/pvdisplay.8.php pvdisplay]png|thumb|left|85px|*[http://www.centos.org/docs/5/html/Deployment_Guide-en-US<b>USB key</s1-system-config-lvm.html system-config-lvm] b><br>(Tutorialfor backups)*[http://linuxmanpages.com/man8/lvextend.8.php lvextend]*[http://linuxmanpages.com/man8/resize2fs.8.php resize2fs]*[http://linuxmanpages.com/man8/lvcreate.8.php lvcreate]*[http://linuxmanpages.com/man8/lvreduce.8.php lvreduce]*[http://linuxmanpages.com/man8/pvcreate.8.php pvcreate]*[http://linuxmanpages.com/man8/vgextend.8.php vgextend]|*width="10%" |[http://linuxmanpages.com/man8/mount.8.php mount]*[httpImage://linuxmanpageslog-book.compng|thumb|left|70px|<b>Lab4 Log Book</man8/umount.8.php umount]*[http://linuxmanpages.com/man8/useradd.8.php useradd]*[http://linuxmanpages.com/man8/userdel.8.php userdel]*[http://linuxmanpages.com/man8/usermod.8.php usermodb>]*[http://linuxmanpages.com/man8/groupadd.8.php groupadd]*[http://linuxmanpages.com/man8/groupdel.8.php groupdel]
|}
==Resources on the webMy Toolkit (CLI Reference)==Additional links to tutorials and HOWTOs:
{|width="50%" cellpadding="15"|- valign="top"|width="10%" |<u>User Management:* </u>[http://unixhelp.ed.ac.uk/CGI/man-cgi?useradd+8 useradd]<br>[Logical Volume Managementhttp://unixhelp.ed.ac.uk/CGI/man-cgi?userdel+8 userdel]<br>[http://unixhelp.ed.ac.uk/CGI/man-cgi?usermod+8 usermod] ('''Note<br>[http:''' It is recommended to return to this guide as a reference when performing the next several investigations)//unixhelp.ed.ac.uk/CGI/man-cgi?groupadd+8 groupadd]<br>[http:* //unixhelp.ed.ac.uk/CGI/man-cgi?groupdel+8 groupdel]|width="10%" |<u>Managing Services</u>[http://wwwunixhelp.ed.thegeekstuffac.comuk/2011CGI/man-cgi?chkconfig+8 chkconfig]<br>[http:/05/ext2unixhelp.ed.ac.uk/CGI/man-ext3-ext4cgi?service+8 service]<br>[http:// Linux File Systems (ext2www.dsm.fordham.edu/ext3cgi-bin/ext4)man-cgi.pl?topic=systemctl systemctl]<br>|width="10%" |<u>Miscellaneous</u>:* [http://tldpman7.org/HOWTOlinux/man-pages/Partitionman5/fdisk_partitioningpasswd.5.html Partitioning with fdisk/etc/passwd]<br>:* [http://wwwman7.org/linux/man-tutorialpages/man5/group.5.infohtml /modulesetc/group]<br>[http://man7.php?name=MContent&pageid=282 Mounting org/linux/ Unmounting Fileman-systemspages/man5/shadow.5.html /etc/shadow]<br>:* [http://wwwarchive.itwirelinuxfromscratch.comorg/businessblfs-itmuseum/1.0/BLFS-news1.0/postlfs/skel.html /etc/open-sourceskel]<br>[http://zenit.senecac.on.ca/wiki/index.php/14446-uid-and-gid-the-basics-of-linux-user-admin UID and GID explainedInit_vs_systemd init vs systemd]|}
= Software Package INVESTIGATION 1: User/Group Management =
== Investigation 1User account management is a very important operation that a Linux sysadmin does on a consistent basis. The sysadmin not only needs to add or remove user accounts by issuing commands, but may need to automate user account creations a large number (batch) of potential employees. There are many features with the Linux command to create new users including: How do you query specification of a home directory, type of shell used, name, password and time-limit (referred to as "aging") for a new user account. Remove user accounts also have options such as removing the user account but keeping the RPM database? ==home directory for reference or evidence of "wrong-doing"
RPM maintains a database of installed software. This information is very useful In your ULI101 course, you learned to change permissions for directories and files relating to system administratorsuser, same group members and other group members. In this course, since you are the previous lab you queried that database using RPM sysadmin with the -q argument. When you query the RPM databaseroot privileges, you can separately specify::* Do an <u>operational task</u> on one create or more packages (like installing or removing a package), using a '''select-option''':* What <u>information</u> you want about those packages, using a '''query-option'''remove groups as well as change the ownership of directories and files! We will now learn to perform key user account management operations in this section.
'''Perform the following steps== Part 1:'''The /etc/passwd file ==
(Perform investigations # Look at the <b><code><span style="color:#3366CC;font-size:1 .2em;">/etc/passwd</span></code></b> file.# Make note of the contents of that file.# Read about the file: http://man7.org/linux/man- 3 in your host machine pages/man5/passwd.5.html # Make sure you know what information each field contains.# Why do you think there are so many users?# Look at the names of the users. What do you think these user names represent? Are they people?# What is the numeric user ID (UID) of the root user?# The user IDs of real users (c6hostpeople)are different from the user IDs of system accounts. What is the pattern?
# Using information from '''Answer the man page for <code>rpm<Part 1 observations /code>, fill questions in this information:your lab log book.'''
{|width="100%" border="1" cellpaddingPart 2: Adding users =="5"|-!Option!Meaning!Select or query option?!Example command|-| -a|Select all packages|select-option| |-| -l| | | |-| -i|Show the package information.| | |-| -f filename| | | |-|packagename|Select just this package|select-option| |}
'''Answer the Investigation 1 observations / table contents in your lab log book.'''
#Perform this part in your '''centos1''' VM.# Read the man page for the <b><code><span style="color:#3366CC;font-size:1.2em;">useradd</span></code></b> command.# Create three fictitious users (make-up their userids and full names. Give each of these newly-created users a password.# Grep the <b><code><span style="color:#3366CC;font-size:1.2em;">/etc/passwd</span></code></b> file for each of the new users.#* What is the '''home''' directory of each user?#* What '''group''' is each user in?#* What other information can you provide regarding these users?#* Where are the '''passwords''' stored?# Look at the man page for '''/etc/shadow''' using the command: <b><code><span style="color:#3366CC;font-size:1.2em;">man 5 shadow</span></code></b>#* Grep the <b><code><span style="color:#3366CC;font-size:1.2em;">/etc/shadow</span></code></b> file for each of the new users.#* Make note of this information. # Create two new dummy users, <b><code><span style="color:#3366CC;font-size:1.2em;">ops235_1</span></code></b> and <b><code><span style= Investigation 2"color: #3366CC;font-size:1.2em;">ops235_2</span></code></b>.# 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:<br>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 install and remove software notice?#* Create a new file in this directory with RPM? the following command: <b><code><span style="color:#3366CC;font-size:1.2em;">touch foo</span></code></b>#* Create a new user named <b><code><span style="color:#3366CC;font-size:1.2em;">foobar</span></code></b>, with the option to automatically create a home directory.#* Look at the contents of foobar's home directory. What do you notice?# Be sure to record your observations in your lab notes.#Issue the man pages for the '''useradd''' command. Explain the purpose of using the '''-e''' option for the ''useradd'' command. Try to think what would be the purpose for a Linux sysadmin to use this option when creating new users.
# Use the graphical file manager (Nautilus) to change to the directory on your Installation DVD. Go to the sub-directory called '''Packages'''. It should contain a file called: <code>lynx-2.8.6-27.el6.x86_64.rpm</code># Execute Answer the following command: <code>rpm -i lynx-Part 2.8.6-27.el6.x86_64.rpm<observations /code># Issue an RPM query to check that lynx is installed. Record this command questions in your lab log-book.# Issue the following command: <code>rpm -e lynx</code># Issue an RPM query to verify that lynx is no longer installed. Record this command in your lab log-book.# Issue the following command: <code>rpm -i elinks-0.12.rpm</code>. Did it work? Explain in your lab log-book why this command may not have worked. '''
'''Answer the Investigation 2 observations / questions in your lab log book.'''== Part 3: Managing Groups ==
#Remain in your '''centos1''' VM for this section.# Read the man page for the <b><code><span style="color:#3366CC;font-size:1.2em;">groupadd</span></code></b> and <b><code><span style= Investigation 3"color:#3366CC;font-size: How do 1.2em;">groupdel</span></code></b> commands.# Note which option allows you install and remove software with to set the Group ID number ('''GID'yum'') when you create a new group.# Examine the file <b><code><span style="color:#3366CC;font-size:1.2em;">/etc/group</span></code></b>#* Which values of GID are reserved for system accounts?#* Which values of GID are reserved for non-system user accounts?#* 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 <b><code><span style="color:#3366CC;font-size:1.2em;">ops235</span></code></b> with a GID of <b><code><span style="color:#3366CC;font-size:1.2em;">600</span></code></b>.#* The management at your organization have concerns regarding some irresponsible users on your system.#** Add a new group named '''investigation'''.#** Look at '''/etc/group''' and note the GID of group called '''investigation'''.#** What GID is given to a new group if you do not specify it?#** In the file, add those users to the end of the concerned group (separate each user-name with a comma).#** Those individuals have explained their actions to management and the crisis has been resolved. Delete the '''investigation''' group.#** Look at '''/etc/group''' again and note the change.
{{Admon'''Answer the Part 3 observations /note|Internet Connection|In order for yum to work you require a connection to the Internetquestions in your lab log book. Establish this connection by using the browser to log into SeneNET}}'''
# Change to your home directory.== Part 4: Deleting / Modifying Users ==
#Remain in your '''centos1''' VM for this section.# Read the man page for the '''userdel''' command. Note which option automatically removes the users home directory when that user is deleted.# Delete the user '''ops235_1''' using the command <olb><code> <li valuespan style="2color:#3366CC;font-size:1.2em;">Issue the command: userdel ops235_1<code/span>yum install elinks</code> and answer <code>y</codeb> to # Delete the question about installation. <ol type="a"> <li>Where did user '''ops235'yum'' get _2 using the elinks softwaresame command with the option which removes the home directory of the user.# Check the contents of the /home directory. What do you notice?# Check the contents of the <b></licode> <lispan style="color:#3366CC;font-size:1.2em;">Why could ''yum'' install elinks when rpm couldn't?/etc/group</lispan> </olcode> </lib>file. What do you notice?# Read the man page for the usermod command. Note which options change the user's full name, primary group, supplementary groups, and shell. <li>Issue an RPM query to verify # Create a new user account called '''noobie''' for the employee: '''"Really Green"''' . Assign a password for that elinks is installednewly created user. Record # Management has indicated that this employee be on on probation for 3 months. Use the '''usermod''' command to set the account for noobie to expire in 3 months from this day as part of the security policy of this organization.# Add each of your lab log-booknew users to the group ops235 (in other words, add ops235 to each user as a supplementary group).# Examine </lib> <licode>Issue the command<span style="color:#3366CC;font-size: 1.2em;">/etc/group<code/span>yum remove elinks</code></lib>. What has changed? <li>Issue an RPM query # Use the '''usermod''' command to change the full name of the user account '''noobie''' from '''"Really Green"''' to verify '''"Outstanding Employee"'''. Examine the result of running that elinks is no longer installed. Record this command in your lab log-book.the </lib> <licode>Issue this command<span style="color:#3366CC;font-size: <code1.2em;">yum info cups/etc/passwd</codespan></licode></olb>file. What has changed?::* Based on # Use the '''usermod''' command to extend the result, do you think that cups is a useful package use of their account for your system? If not, try removing it5 years as of today.<ol> <li value="8">Unused and unneeded software can present a security risk and ties up disk space needlessly. Find at least 4 other packages (for example: games, sound & video, etc) that you're not using on your system, and remove them. # Be careful sure to ensure that removing those packages does not also remove other software that you do needrecord your observations in your lab notes.</li></ol>
'''Answer the Investigation 3 Part 4 observations / questions in your lab log book.'''
==Archiving Files / Compiling Software from Source Code==
Archive files are often used to contain source code for software; in this lab you will also be compiling software from a source code archive.=INVESTIGATION 2: Managing System Services and Run-levels=
{{Admon/note|Do Many students may think that the following topic is small and "not Shut-Down VMs Until Instructed|You will be running all 3 VMs eventually when performing this tutoriala big deal". Those students may say, Leave all VMs '''"How hard is running until you are instructed to shut them down at the end of this lab.|}}and stopping services?"'''
===Investigation 1: How do you create an archive file?==={{Admon/note|Use centos3|Perform these steps The process may not be hard, but knowing how to stop, start, restart and check the status of services is absolutely critical to a Linux server. '''Aside from learning to trouble-shoot problems''' by checking the status of running services, '''understanding how to manage services is critical to help protect a Linux server from penetration''' (this term is referred to as "'''Hardening a system'''"). Sometimes it is "what we don't know" that can harm us. One key element in hardening a computer system is to disable non essential networkng services to allow IDSs ('''Intrusion Detection Systems''') to focus on a narrower range of policy violations. A Debian-based penetration testing distribution called '''Kali''' (formerly referred to as '''"BackTrax"''') allows sysadmins and security professionals to identify vulnerabilities in their computer systems, and thus improve (harden) their systems against penetration. Learning to monitor the status, enable and disable networking services underlies the '''centos3Backtrax''' virtual machinemotto:<br><br>'''''"The quieter you are, then more you will hear.}}.."'''''<br><br>
#Boot up your '''centos3''' VM.#Change your working directory to <code>/usr/share/doc/sudo*</code>#Use the tar (tape archiver) command to create an archive file named <code>/tmp/archive1.tar</code>#*<code>tar cvf /tmp/archive1.tar .</code>=== Part 1: How do we Manage System Services? ===
{{Admon/important | Warning! | Don't miss the We have seen that maintaining unneeded '''.packages can be a security risk''' at the end of the <code>tar</code> commands below! It specifies what should go into due to the archive: unnecessary increase in the contents complexity of the current directoryyour 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'''.}}
#Use your '''centos2''' VM for this part.
<ol>
<li value="42">What do Use the options c, v, and f mean?'''man''' pages to learn about the '''service''' command.</li> <li>Record Issue the archive file size.following Linux command: </liul> <li>Compress the file using <codeb>gzip</code><span style="color: <ul#3366CC;font-size:1.2em;"> service --status-all<li/span></code>gzip /tmp/archive1.tar</codeb></li> </ul>
</li>
<li>Record Note the archive file size after compressionservices that are currently running.</li> <li>Make sure you're still in Use the command <b><code><span style="color:#3366CC;font-size:1.2em;">service iptables stop</usrspan></sharecode></docb> to stop the service named '''iptables'''</sudo*li> <li>Run a command to verify that the '''iptables''' service has stopped.<br><br>'''NOTE:''' Although the service command seems to work, it is <u>'''deprecated'''</codeu> (i.e. "out-dated:). It has been replaced by using the [http://zenit.senecac.on.ca/wiki/index.php/Init_vs_systemd#systemd_Command_Usage systemctl] command. This is a command based upon a newer method of starting and then create managing system services called [http://zenit.senecac.on.ca/wiki/index.php/Init_vs_systemd systemd] (which replaces init - the "initialization table"). This method allows services to run more independently of each other, so that a compressed archiveservice may be stopped without other dependent services to be stopped as well.<br><br>The most common '''systemctl''' commands are shown below (it is optional to include the filename extension '''.service''' after the service-name):<ul> <li><codespan style="font-family:courier;font-size:1.2em;font-weight:bold;">tar cvzf '''systemctl list-units --all'''</tmpspan> &nbsp; (get a listing of all service names. Can pipe to grep to list service you are interested in)</archive2li><li><span style="font-family:courier;font-size:1.tgz 2em;font-weight:bold;">'''systemctl status service-name'''</span> &nbsp; (Confirm status of a service - running or not-running)</li><li><span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl stop service-name'''</codespan> &nbsp; (stop a service)</li><li><span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl start service-name'''</span> &nbsp; (start a service)</li><li><span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl restart service-name'''</span>&nbsp; (restart a service)</li> <li><span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl enable service-name'''</ulspan> &nbsp; (enable service so service runs upon system startup)</li> <li>What <span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl disable service-name'''</span> &nbsp; (disable service so it does the NOT run upon system startup)<br><br><code/li>z</codeul> option do?</li> <li>Compare If you reboot now - the iptables service will be turned back on. We don't want it on though, it causes students headaches.<br>To turn it off permanently we need to use the sizes of '''systemctl''' command:<b><code>/tmp/archive1<span style="color:#3366CC;font-size:1.tar.gz2em;">systemctl disable iptables</codespan> and </code></tmpb><br>(the '''chkconfig''' command used to be the way to enble/archive2disable services, but is now deprecated).tgz</codeli> <li>Use the '''systemctl''' command to verify that the '''iptables''' service is no longer running ('''hint:''' issue command, and pipe to grep "'''iptables'''"). <li>Reboot and confirm that it's no longer running. Why are they so close in size?</li>
</ol>
'''Answer the Investigation Part 1 observations / questions in your lab log book.''' ===Investigation 2: How do you restore files from an archive?==={{Admon/note|Remain in your centos3 VM|Perform these steps in the '''centos3''' virtual machine.}}#Create the directory <code>/tmp/extract1</code>#Change to the <code>/tmp/extract1</code> directory.#Move the file archive1.tar.gz to your current directory.#Unzip the first archive you created:#*<code>gunzip archive1.tar.gz</code>#Extract the files from the first archive:#*<code>tar xvf archive1.tar</code>#Are all the files there? #Compare <code>/tmp/extract1/README</code> and <code>/usr/share/doc/sudo*/README</code>. Are they exactly the same? Why?#Create the directory <code>/tmp/extract2</code>#Move the file archive2.tgz to the <code>/tmp/extract2</code> directory.#Extract the files from the second archive:#*<code>tar xvzf /tmp/extract2/archive2.tgz</code>#Note that this time a separate <code>gunzip</code> command was not needed. Why?#Repeat the previous command, leaving out the option "z". Does it work? Why?#Compare the <code>README</code> file in this directory with the original file. Are they exactly the same? '''Answer the Investigation 2 observations / questions in your lab log book.'''
===Investigation 3Part 2: How do you build software from source codewe Manage Runlevels?===
Now that you know how Running servers in graphical mode will make your system most likely to create and decompress "zipped tarball archives", we will demonstrate how be penetrated. The X-windows framework can be vulnerable to install applications from websites containing attacks when these types of archivesservers are connected to the Internet. Although this method This is not as "user-friendly" as using the yum or rpm commandwhy when you install server versions of Linux, this method is useful if the application is NOT contained they work in regular software repositoriestext-based mode only...{{Admon/note|Use centos2|Perform these steps Desktop versions of Linux are then installed on workstations (working in graphical mode) that connect to the '''centos2''' virtual machineserver (for security reasons).}}
In order to build software from source code, you must have The Linux sysadmin can also change the appropriate software development tools run-level (such as make and gccor state) of a graphical Linux server to run in text-based mode and libraries (such as GTK) installedrun the graphical mode by issuing a command when graphic mode is required. The required tools run-level term is now deprecated in Fedora, and will vary depending on the computer languages used likely be deprecated in RHEL/CentOS at some point as well, but for now this is what the software being builtindustry is using.
# Issue the following command to install a basic set of development tools and libraries:<br /><code>yum groupinstall "Development Tools" "Development Libraries"</code>
{{Admon/note|Installing Development Libraries|In the future, remember the above procedure whenever installing software from source. Sometimes, you need to install additional tools or libraries in order to compile a particular software package}}
#Perform this part in both your '''centos2''' and '''centos3''' VMs.
<ol>
<li value="32">Go to Issue the directory following Linux command: <ul> <li><b><code><span style="color:#3366CC;font-size:1.2em;">runlevel</tmpspan></code></b></li> </ul> </li> <li>Use Note the difference in output between '''centos2''' and '''centos3'''.<code/li>wget </codeli> You can use the '''init''' command to download change the "tar ball" that contains the source code for the NLED text editorcurrent run-level. See a list of runlevels [https://www.centos.org/docs/5/html/5.2/Installation_Guide/s2-init-boot-shutdown-rl.html here]. <code/li>wget</codeli> is a Use the '''man''' command-line tool to download files from learn how to use the web using '''init''' command. Use this command to change the http or ftp protocolscurrent run-level in '''centos2''' to '''3'''.What happened?</li> <li>Issue the following Linux command:
<ul>
<li><b><code>wget http<span style="color://cdot#3366CC;font-size:1.senecac.on.ca2em;">startx</softwarespan></nled/nled_2_52_src.tgzcode></codeb></li>
</ul>
</li>
<li>Extract the files. Change to the newly-extracted directory (<code>/tmp/nled-2.52</code>)</li>
<li>Check to see if there is a file named <code>configure</code>. If so, run it; if not, skip this step. (Most but not all source code archives contain this file)</li>
<li>Check to see if there is a file named <code>Makefile</code> or <code>makefile</code>. If so, type the command:
<ul>
<li><code>make</code></li>
<li>Did the command work? Why? Use the <code>yum</code> command to install the package '''gcc'''. What do you think the package ''gcc'' does?</li>
</ul>
<li>Reissue the <code>make</code> command. Where you successful? What does <code>make</code> do?</li>
<li>Issue the command as root: <code>yum list ncurses</code>. What do you see? Issue the command at root: <code>yum search ncurses</code>. What do you observe?</li>
<li>In this case, you need to install the ncurses development libraries as well. Issue the following command as root: <code>yum install ncurses-devel.x86_64</code>. Now issue the command: <code>make</code></li>
<li>Some software distributed as source code can automatically install itself. Try this command:
<ul>
<li><code>make install</code></li>
</ul>
</li>
<li>Most but not all source code archives include the capability of installing themselves this way.What happens?</li> <li>If the command Log-off your graphical system. You should return to your shell prompt.<code/li>make install </codeli> does not work (how Using systemd requires a different method of setting text mode and graphical mode. You can you tell? What command did you learn from ULI101 refer to confirm that this command cannot be run from the command line?), copy the <code>nled</code> program manuallylink for future reference: <ul> <li><code>cp nled [http:/usr/localfedoraproject.org/bin<wiki/code>Systemd#How_do_I_change_the_runlevel.3F How to Change Run-Levels with Systemd]</li> </ul> </li> <li>Test <code>nled</code> to Restart your centos2 machine, and make sure certain that it works.runs in '''graphical''' mode</li> </li>Why did copying the nled executable would you want to /usr/local/bin allow the nled command to be make a graphical Linux system run by name anywhere in the command prompttext-based mode?</li>
</ol>
'''Answer the Investigation 3 observations / questions in your lab log book.'''
= User/Group Management =
== Investigation 4: The '''Answer Part 2 observations /etc/passwd file ==questions in your lab log book.'''
# Look at the /etc/passwd file.
# Make note of the contents of that file.
# Read about the file: http://linux.die.net/man/5/passwd
# Make sure you know what information each field contains.
# Why do you think there are so many users?
# Look at the names of the users. What do you think these user names represent? Are they people?
# What is the numeric user ID (UID) of the root user?
# The user IDs of real users (people) are different from the user IDs of system accounts. What is the pattern?
== Investigation 5INVESTIGATION 3: Adding users =LOOKING AHEAD =
==Automating Routine Tasks (Shell Scripting)=={|width="40%" align="right" cellpadding="10"|- valign="top"|{{Admon/notetip|Use centos1Bash Shell Scripting Tips:|Perform these steps <br><ul><li>'''The case statement:'''<br><br>The case statement is a control-flow statement that works in a similar way as the if-elif-else statement (but is more concise). This statement presents scenerios or "cases" based on values or regular expressions (not ranges of values like if-elif-else statements). After action(s) are taken for a particular scenerio (or "case"), a break statement (''';;''') is used to "break-out" of the statement (and not perform other actions). A default case (*) is also used to catch exceptions.<br><br><u>'''Examples (try in shell script):'''</u><br><br>''read -p "pick a door (1 or 2): " pick<br>case $pick in<br>&nbsp; 1) echo "You win a car!" ;;<br>&nbsp; 2) echo "You win a bag of dirt!" ;;<br>&nbsp; *) echo "Not a valid entry"<br>&nbsp;&nbsp;&nbsp;&nbsp; exit 1 ;;<br>esac''<br><br>''read -p "enter a single digit: " digit<br>case $digit in <br>&nbsp; [0-9]) echo "Your single digit is: $digit" ;;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; *)&nbsp;echo "not a valid single digit"<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; exit 1 ;;<br>esac''<br><br></li><li>'''The getopts function:'''<br><br></li></ul>The getopts function allows the shell scripter to create scripts that accept options (like options for Linux commands). This provides the Linux administrator with scripts that provide more flexibility and versatility. A built-in function called '''centos1getopts''' system(i.e. get command options) is used in conjunction with a '''while''' loop and a '''case''' statement to carry out actions based on if certain options are present when the shell script is run. The variable '''$OPTARG''' can be used if an option accepts text (denoted in the getopts function with an option letter followed by a colon. Case statement exceptions use the ''':)''' and '''\?)''' cases for error handling.<br><br>'''<u>Example of getopts</u>''' (try in script and run with options)<br><br>''while getopts abc: name<br>do<br>&nbsp; case $name in<br>&nbsp; &nbsp; a) echo "Action for option \"a\"" ;;<br>&nbsp; &nbsp; b) echo "Action for option \"b\"" ;;<br>&nbsp; &nbsp; c) echo "Action for option \"c\""<br>&nbsp; &nbsp; &nbsp; &nbsp; echo Value is: $OPTARG" ;;<br>&nbsp; &nbsp; :) echo "Error: You need text after -c option"<br>&nbsp; &nbsp; &nbsp; &nbsp; exit 1 ;;<br>&nbsp; &nbsp; \?) echo "Error: Incorrect option"<br>&nbsp; &nbsp; &nbsp; &nbsp; exit 1 ;;<br>esac''<br>done<br><br>}}|}
# Read the man page for the useradd command.# 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.# 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?# 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. # Create two new dummy users, ops235_1 and ops235_2.# Investigate the home directory of one of your new users.#* What files are there? Be sure We will now use shell scripting to include hidden files.#* What do you think these files are used for?#* How does help automate 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 task for a new user. What do you notice?#* Create a new file in this directory with the following command: <code>touch foo</code>#* Create a new user named foobar, with the option Linux adminstrator to automatically create a home directory.#* Look at the contents of foobar's home directory. What do you notice?# Be sure to record your observations in your lab notesregular user accounts.
{{Admon/note|Use centos3|Perform these steps in the '''centos3''' virtual machine.}}
# Add your matrix account user to '''centos3'''.
#You will be using your '''c7host''' machine for this section.#Download, study, and run the following shell script. Issue the command:<br><b><code><span style== Investigation 6" pointer-events:none;cursor:default;color:#3366CC;font-size:1.2em;">wget https: Managing Groups ==//scs.senecac.on.ca/~murray.saul/user-create.bash</span></code></b>#Try to understand what these Bash Shell scripts do, and then run the script as root. After running the shell script, view the contents of the '''/home''' directory to confirm.
{{Admon/note|Use centos1|Perform these steps in the '''centos1''' virtual machine.}}
# Read Although the man page for the groupadd and groupdel '''zenity''' command is a "user-friendly" way to run shell scripts, Linux administrators usually create shell scripts that resemble common Linux commands.# Note which option allows In this lab, you will learn to set the Group ID number (GID) when you create a new group.# Examine shell script using the file /etc/group#* Which values of GID are reserved for system accounts?#* Which values of GID are reserved for non-system user accounts?#* What is getopts function to make your shell script behave more like actual Linux commands (including the lowest available GID number for non-system users?#* What is the default group name use of a new user?#* Add a new group named ops235 with a GID of 600options).#* You are angry at some irresponsible users Refer to the notes section 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 right-hand-side for reference about the idiots group.#** Look at /etc/group again '''case''' statement and note the change'''getopts''' function.
Be sure to record your observations in your lab notes.
<ol><li value="3">Open a Bash shell terminal and login as root.</li><li>Use the wget command to download the input file called user-data.txt by issuing the command:<br><b><code><span style="color:#3366CC;font-size:1.2em;">wget https://scs.senecac.on.ca/~murray.saul/user-data.txt</span></code></b></li><li>View the contents on the user-data.txt file to confirm there are 3 fields (username, fullname, and e-mail address)which are separated by the colon (:) symbol.<li><li>Use a text editor (such as <b><code><span style="color:#3366CC;font-size:1.2em;">vi</span></code></b> or <b><code><span style="color:#3366CC;font-size:1.2em;">nano</span></code></b>) to create a Bash Shell script called: <b><code><span style="color:#3366CC;font-size:1.2em;">createUsers.bash</span></code></b> in /root's home directory.</li><li>Enter the following text content into your text-editing session:</li></ol><code style= Investigation 7"color: Deleting #3366CC;font-family:courier;font-size:.9em;margin-left:20px;"><br>&#35;!/bin/bash <br><br>&#35; createUsers.bash<br>&#35; Purpose: Generates a batch of user accounts (user data stored in a text file)<br>&#35;<br>&#35; USAGE: /root/createUsers.bash [-i {input-path}] <br>&#35;<br>&#35; Author: *** INSERT YOUR NAME ***<br>&#35; Date: *** CURRENT DATE ***<br><br>if [ $PWD != "/root" ] # only runs if in root's home directory<br>then<br>&nbsp;echo "You must be in root's home directory." >&2<br>&nbsp;exit 1<br>fi<br>if [ "$#" -eq 0 ] # if no arguments after command<br>then<br>&nbsp;echo "You must enter an argument" >&2<br>&nbsp;echo "USAGE: $0 [-i {input-path}]" >&2<br>&nbsp;exit 2<br>fi<br></code><br><ol><li value="6">Save your editing session, but remain in the text editor.</li><li>The code displayed below uses the getopt function set the input file pathname or check for invalid options or missing option text. Add the following code</li></ol><br><code style="color:#3366CC;font-family:courier;font-size:.9em;"><br>outputFlag="n"<br>while getopts i: name<br>do<br>&nbsp;case $name in<br>&nbsp; &nbsp;i) inputFile=$OPTARG ;;<br>&nbsp; &nbsp;:) echo "Error: You need text after options requiring text"<br>&nbsp; &nbsp; &nbsp; &nbsp;exit 1 ;;<br>&nbsp; &nbsp;\?) echo "Error: Incorrect option"<br>&nbsp; &nbsp; &nbsp; &nbsp; exit 1 ;;<br>&nbsp;esac<br>done<br></code><ol><li value="6">Save your editing session, but remain in the text editor.</li><li>The code displayed below uses logic to exit the script if the input file does not exist. Command substitution is used to store each line of the input file as a positional parameter. There is one subtle problem here: The full names of the users contain spaces which can create havoc when trying to set each line as a separate positional parameter. In this case the sed command is used to convert spaces to plus signs (+), which will be converted back later. Finally, a '''for''' loop is used to create each account ('''useradd''') and mail the user their account information ('''mail'''). Add the following code:</li></ol><br><code style="color:#3366CC;font-family:courier;font-size:.9em;"><br>if [ ! -f $inputFile ]<br>then<br>&nbsp; echo "The file pathname \"$inputFile\" is empty or does not exist" >&2<br>&nbsp; exit 2<br>fi<br><br>set $(sed 's/ /+/g' $inputFile) # temporarily convert spaces to + for storing lines as positional parameters<br><br>for x<br>do<br>&nbsp; &nbsp; userPassWd=$(date | md5sum | cut -d" " -f1)<br>&nbsp; &nbsp; useradd -m -c "$(echo $x | cut -d":" -f2 | sed 's/+/ /g')" -p $userPassWd $(echo $x | cut -d":" -f1)<br>&nbsp; &nbsp; mail -s "Server Account Information" $(echo $x | cut -d":" -f3) <<+<br>&nbsp; &nbsp; Here is your server account information:<br>&nbsp; &nbsp; servername: myserver.senecac.on.ca<br>&nbsp; &nbsp; username: $(echo $x | cut -d":" -f1)<br>&nbsp; &nbsp; password: $userPassWd<br>&nbsp; &nbsp; Regards,<br>&nbsp; &nbsp; IT Department<br>+<br>done<br><br>echo -e "\n\nAccounts have been created\n\n"<br>exit 0<br></code>
{{Admon/note|Use centos1|Perform these steps in <ol><li value="8">Save, set permissions, and then run that shell script for the input text file '''centos1user-data.txt''' virtual machine.}} # Read Did it work? Try running the man page for the userdel commandscript without an argument - What did it do? </li><li>You have completed lab4. Note which option automatically removes Proceed to Completing The Lab, and follow the users home directory when that user is deletedinstructions for "lab sign-off".</li></ol>
# Delete the user ops235_1 using the command <code>userdel ops235_1<'''Answer Investigation 3 observations /code># Delete the user ops235_2 using the same command with the option which removes the home directory of the userquestions in your lab log book.# Check the contents of the /home directory. What do you notice?# Check the contents of the /etc/group file. What do you notice?'''
Be sure to record your observations in your lab notes. =LAB 4 SIGN-OFF (SHOW INSTRUCTOR) = Investigation 8: Modifying users == {{Admon/noteimportant|Use centos1|Perform these steps in the '''centos1''' virtual machine.}} # Read the man page for the usermod command. Note which options change the user's full nameIf you have successfully completed this lab, primary group, supplementary groups, and shell. # Add each make a new backup of your new users to the group ops235 (in other words, add ops235 to each user virtual machines as well as a supplementary group).# Examine <code>/etc/group</code>. What has changed?# Use the usermod command to associate each of your pod mates' full name to their user name. With each change, examine their entries in the <code>/etc/passwd</code> file. What has changed?# Be sure to record your observations in your lab noteshost machine.|}}
= Completing '''Arrange proof of the lab =following on the screen:'''
{{Admon<ol><li><span style="color:green;font-size:1.5em;">&#x2713;</span> '''centos1''' VM:<blockquote><ul><li>Account created on '''centos1''' VM</li><li> List contents of '''/etc/group''' file (ops235 group)</important|Time for a new backup!|If you have successfully completed this lab, make a new backup li><li>List contents of your virtual machines'''/etc/passwd''' file (created accounts)</li></ul></blockquote><li><span style="color:green;font-size:1. Remember to also make a backup of the new second virtual disk drive 5em;">&#x2713;</span> '''centos2''' VM:<blockquote><ul><li>Display current run-level status on ''centos1'centos2''' VM</li></ul></blockquote></li></li><li><span style="color:green;font-size:1.5em;">&#x2713;</span>'''c7host''' machine<blockquote><ul><li>Creation of your bash shell script called '''createUsers.bash'''</li></ul></blockquote></li><li><span style="color:green;font- you now have two virtual disks on size:1.5em;">&#x2713;</span> '''Lab4'centos1'', and therefore two image files, and therefore will need two backup fileslog-book filled out.}}</li></ol>
Arrange proof of the following on the screen:
# Two PVs on '''centos1'''.
# Separate <code>/home</code> filesystem (on an LV) in '''centos1'''.
# Account created on '''centos3''' matching your Matrix account.
# List contents of '''/etc/group''' file (ops235 group).
# List contents of '''/etc/passwd''' file (created accounts).
# Fresh backup of the virtual machines.
= Preparing for the = Practice For Quizzes , Tests, Midterm &amp; Final Exam ==
# Describe all of the field in <code>'''/etc/passwd'''</code># What is the command to create a VGuser? PV? LVWhat option to create a home directory for that user? # What is the total size command to change the full name of the "main" VG on your systeman already-created user?# How do you create What is the command to delete a LVuser account?# How do you delete an LVWhat option allows for the user's home directory to be removed as well?# How would you add What is the disk partition <code>/dev/sdb7</code> command to your volume create a group "main"?# How would you increase What is the size of the root filesystem by 50 MBcommand (or steps) to include a user in a newly-created group?# What is the purpose of <code>'''/etc/fstabshadow'''</code>?# What is the purpose of <code>'''/etc/shadowskel'''</code>?# What does the term run-level mean?# How to set the run-level of a Linux system to text-based only? How to set to graphical mode?# What is the command to view the status of running services?# What is the command to start a service (like httpd, or sshd)?# What is the command to start a service?# Can a service be stopped and started by issuing just one command?
[[Category:OPS235]]
[[Category:OPS235 Labs]]
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