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{{Admon/caution|THIS IS AN OLD VERSION OF THE LAB|'''This is an archived version.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 =
==Overview==
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[[Image:ip.png|thumb|right|150px|Some computer networks (such as computer labs) configure their workstations for '''static IP addresses for security and to provide other interesting features such as WOL'''.]]
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[[Image:wifi.png|thumb|right|125px|'''Hot-spots''' offer the ability for users to connect to the Internet via their mobile devices. '''Hybrid solutions''' combine DHCP and fixed IP Address. ]]
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There are various ways in which computers can be networked together. Some computer networks (such as computer labs) configure their workstations for '''static IP addresses for security and to provide other interesting features such as WOL''' (Wake Up on Lan) which allows a signal from a computer system to remotely start all or specified workstations within the lab. '''Hot-spots (such as cafes or airport lounges) offer the ability for users to connect to the Internet (via DHCP) from their mobile devices''' (notebooks, netbooks, tablets, or smart phones). Finally, there are '''hybrid solutions that may offer both fixed IP address (computer workstations) and allow for wireless connections (via DHCP) to a mobile devices''' (like at your Seneca computer labs).
In lab6, you learned to connect your VMs to a VPN using a fixed IP Address. In this final lab, you will learn how to setup, and run set-up a '''DHCP server on your centos3 machine, and then test-out the DHCP server by setting up your other VMs ''' to receive an automatically assign IP addresses from the DHCP serverAddresses upon connection requests.
<u>Main Objectives</u>
==Minimum Required Materials==
{|cellpadding="15" width="40%"#INVESTIGATION_3:_SECURING_THE_SSH_CONNECTION
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*[http://man7.org/linux/man-pages/man1/tail.1.html tail]
*[http://linux.die.net/man/8/chkconfig chkconfig]
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*[https://www.freebsd.org/cgi/man.cgi?query=dhcpd.conf&sektion=5&apropos=0&manpath=FreeBSD+9.0-RELEASE+and+Ports dhcpd.conf]
|width="90%" |The client sends a '''message of acceptance to the server'''. In turn, the client receives from the server a '''packet of information''' containing the lease duration and other configuration information
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== Part 1: Installation of a DHCP==
{| width="40%" align="right" cellpadding="10"|- valign="top"|{{Admon/note|VM Backups and Yum Updates|Before proceeding with this lab make certain that you have backed-up from lab7, and then perform a '''yum update''' on all machines (including your VMs)|}}|}# Perform this section in your '''centos3''' VM.# It is advisable to perform a yum update on your host and all three of your VM's.# It is also advisable that you properly backed up your VMs from lab7.<br><br>The version of DHCP server that comes with CentOS is maintained and distributed by the Internet Software Consortium (http://www.isc.org). The source package that you can download from ISC includes not only the DHCP server, but also a DHCP client and a DHCP relay agent. CentOS separates it into two RPM packages: the DHCP client package and the DHCP server package. The DHCP client package is installed by default by the workstation installation.<br><br># To check that you have <codeb>dhclient</codeb> installed, enter the command:
#:: <b><code><span style="color:#3366CC;font-size:1.2em;">rpm -q dhclient</span></code></b>
# If the package is not installed, you will get the message ''"package dhclient is not installed"'', otherwise, you will get the version information of the rpm package. Install the <codeb>dhclient</codeb> package if it was not installed.# Check Issue the following command to see if install the dhcp server package is installed: <b><code><span style="color:#3366CC;font-size:1. If not - 2em;">yum install it.dhcp</span></code></b># Enter the command to list all the files installed from the DHCP server packageby issuing the command: <b><code><span style="color:#3366CC;font-size:1.2em;">rpm -qla dhcp</span></code></b># What file appears to be a sample (example) configuration filefor dhcpd.conf?# Copy the sample '''dhcpd.conf.example''' file to the '''/etc/dhcp''' directory making sure it is named: '''/etc/dhcp/dhcpd.conf'''
'''Answer Part 1 observations / questions in your lab log book.'''
== Part 2: Configuring the DHCP Server==
'''Answer Part 2 observations / questions in your lab log book.'''
# Save your editing session, and exit the text editor.
<ol><li value="56">Open another terminal window (ssh into centos3 from the centos host as user root) and issue the following command:::: <br><b><code><span style="color:#3366CC;font-size:1.2em;">tail -f /var/log/messages</span></code></b><libr><br>(This will show you the last 10 lines of '''/var/log/messages''' continue to display new lines as they are added to the log.)<br><br></li>
<li>In your original terminal prompt attempt to start the '''dhcpd''' service.</li>
<li>You should see new lines being added to the messages file.</li>
<li>If your '''dhcpd''' service starts successfully, try to generate errors by editing the configuration file and introduce an error by removing a semicolon or closing curly bracket.</li>
<li>Restart your '''dhcpd''' service and observe the error messages generated. This is good practice to learn how to trouble-shoot and solve dhcpd errors.</li>
<li>Make certain that you have corrected those errors, and that your dhcpd service works properly.<li>Once the dhcpd service has is running, use the '''systemctl''' command to see if the dhcpd service is enabled. If it is not enabled, use the '''chkconfig''' command to enable the dhcpd service so it started automatically upon boot-up.</li>
</ol>
== Part 4: How do I test my dhcpd service on my virtual network?==
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|{{Admon/note | Identifying DHCP Lease Transaction Information | These messages record the DHCP lease transaction that consists of 4 broadcast packets, DISCOVER, OFFER, REQUEST and ACKNOWLEDGE. Try researching on the internet how this transaction differs from a DHCP lease renewal.}} |}# Use your '''centos2''' and '''centos3''' VMs for this section.# On a your '''centos3 ''' terminal window (via ssh from your c7host machine) make sure that the command <codebr><b>tail -f /var/log/messages</codeb> is running.# On your '''centos2 ''' VM, change the configuration of '''eth0''' (or your interface name) to receive dynamic address configuration(i.e. via graphical application, for IVP4 tab, change ''Address'' from '''Manual''' to '''DHCP''', and '''Apply''' settings)<br>([http://zenit.senecac.on.ca/wiki/index.php/OPS235_Lab_6_-_CentOS7# Save your changes and restart the Part_2:_Configuring_VM_Network_Setup_Graphically_.28system-config-network.29 Refer to Lab6, Investigation1, Part2]).<codebr>NetworkManager</codebr> serviceNote: if you are configuring via command line, make certain to restart the network for centos2.# Logout and restart your '''centos2''' VM.# Observe the messages that get loggedfrom the tail -f command as your centos2 VM starts. You should see output similar to the following:<br><br>::<pre span style="font-family:courier;">Mar 24 13:28:24 centos3 dhcpd: DHCPDISCOVER from 52:54:00:61:00:e7 via eth2</span>::<span style="font-family:courier;">Mar 24 13:28:25 centos3 dhcpd: DHCPOFFER on 192.168.235.51 to 52:54:00:61:00:e7 via eth2</span>::<span style="font-family:courier;">Mar 24 13:28:25 centos3 dhcpd: DHCPREQUEST for 192.168.235.51 (192.168.235.13) from 52:54:00:61:00:e7 via eth2</span>::<span style="font-family:courier;">Mar 24 13:28:25 centos3 dhcpd: DHCPACK on 192.168.235.51 to 52:54:00:61:00:e7 via eth2<br><br></prespan>{{Admon/note | Identifying DHCP Lease Transaction Information | These messages record the DHCP lease transaction that consists of 4 broadcast packets, DISCOVER, OFFER, REQUEST and ACKNOWLEDGE. Try researching on the internet how this transaction differs from a DHCP lease renewal.}}<ol><li value="56">On '''centos2''', confirm the IP address assignment using <b><code><span style="color:#3366CC;font-size:1.2em;">ifconfig</span></code></b></li><li>Has the IP Address changed? If so, how has the IP Address been assigned according to the '''dhcpd.conf''' file settings?</li>
</ol>
== Part 1: Where does the dhcp server store a record of leased addresses?Obtaining Leased Address Infomation=={|width="40%" align="right" |- valign="top"
|{{Admon/note | Use your centos2 and centos3 VMs Purpose of dhcpd.leases File | Complete dhcpd records address leases in this file. If the service is restarted it reads in the following steps on your centos2 file to know which addresses are currently leased and centos3 VMsfor how long.}}
|} # Remain in your '''centos2''' and '''centos3''' VMs for this section.# If your '''centos3 ''' DHCP server successfully issued the proper IP address configuration values to '''centos2''', check the file called :<codebr>'''/var/lib/dhcpd/dhcpd.leases''' in your <u>'''centos3''' VM</codeu># . You should see the similar contents similar to:<br><br>::<prespan style="font-family:courier;">lease 192.168.235.51 {</span>::<span style="font-family:courier;"> starts 3 20105 2015/0307/24 10 17:2857:2534;</span>::<span style="font-family:courier;"> ends 3 20105 2015/0307/24 10 18:17:4834;</span>::<span style="font-family:25courier;"> cltt 3 20105 2015/0307/24 10 17:2857:2534;</span>::<span style="font-family:courier;"> binding state active;</span>::<span style="font-family:courier;"> next binding state free;</span>::<span style="font-family:courier;"> rewind binding state free;</span>::<span style="font-family:courier;"> hardware ethernet 52:54:00:610e:007d:e7a4;</span>}::<span style="font-family:courier;"> client-hostname "centos2";</prespan>{{Admon/note | Purpose of ::<codespan style="font-family:courier;">dhcpd.leases}</codespan> File | dhcpd records address leases in this file. If the service is restarted it reads in the file to know which addresses are currently leased and for how long.}}<ol><li value="3">On the client '''centos2 ''' check the contents of the <codeb>/var/lib/dhclient</codeb> directory. The files in this directory is where the dhclient stores its record of leases.<br><br> '''NOTE:''' If there are no files, then in a shell as root in your centos2 VM issue the command: <b><code><span style="color:#3366CC;font-size:1.2em;">dhclient eth0</span></code></b><br>Then check to see if there is file containing lease information in that directory.<br><br></li>
</ol>
'''Answer Part 1 observations / questions in your lab log book.'''
== Part 2: How can I lease the same address every time? Configuring DHCP server to Continually Lease Same IP Address=={|width="40%" align="right"
|{{Admon/note | Reserving IP Addresses with DHCP | Even though DHCP gives out IP address dynamically, it also has the ability to reserve an IP address for a certain computer. In this sense it's almost as if the client computer has a static IP even though it uses DHCP to get it. This is useful if you want to be able to put entries in your /etc/hosts file and not have to worry about the entry becoming invalid over time. In Linux we refer to this as supplying a fixed address to a host. Microsoft calls it a reservation.}}
|}# Remain in your '''centos2''' and '''cento3''' VMs for this section.# Make certain that you are located in your '''centos3 ''' virtual machine.# Create a host declaration for '''centos2'''. Make sure you record the correct <code>hardware ethernet</code> setting that corresponds to the MAC address of the interface in '''centos2'''.# Give it the fixed-address '''192.168.235.12{{Admon/tip | Avoiding IP Address Conflicts | 42'''<br><br>'''Note:''' When supplying fixed-address it is important that the address assigned is exclusive of any ranges that have been declared. Otherwise it may be possible for 2 different hosts to receive the same address.}}<br><br><ol><li value="35">Start your service and test the address assignment by releasing your current address on '''centos2 ''' and then requesting a new address. Use the following commands on '''centos2''':</li>
</ol>
::: <b><code><span style="color:#3366CC;font-size:1.2em;">ifdown eth1</span></code></b>::: <b><code><span style="color:#3366CC;font-size:1.2em;">ifup eth1</span></code></b><ol><li value="46">Confirm that you received the fixed address you were supposed to.</li>
</ol>
'''Answer Part 2 observations / questions in your lab log book.'''
= LAB 8 SIGN-OFF (SHOW INSTRUCTOR) =
{{Admon/important|Time for a new backup, INCLUDING YOUR VIRTUAL HARD DRIVE!|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 <br><br>''centos3'' Virtual hard-- drives created lab5 are image files and may have data changed as a result of performing this lab. Therefore, you now have two virtual disks on need to be backed up this hard disk image as well!''centos3'', and therefore two image files, and therefore will need two backup files.}} '''Arrange proof of the following on the screen:''' * <ol><li><span style="color:green;font-size:1.5em;">✓</span> '''centos2''' VM:<blockquote><ul><li>'''ifconfig eth0''' shows IP address '''192.168.235.42'''</li><li>DHCP client lease file</li></ul></blockquote><li><span style="color:green;font-size:1.5em;">✓</span> '''centos3''' VM:<blockquote><ul><li>DHCP server log file showing a lease occuring* </li><li>DHCP server configuration file showing subnet and host declaration* </li><li>DHCP server lease file* DHCP client lease file</li></ul></blockquote></li><li><span style="color:green;font-size:1.5em;">✓</span> '''Lab8''' log-book filled out.</li></ol>
= Preparing for = Practice For Quizzes , Tests, Midterm & Final Exam ==
# What protocol and port does dhcp use?
