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{{Admon/caution|THIS IS AN OLD VERSION OF THE LAB|'''This is an archived version.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]
=INVESTIGATION 1: INSTALL AND CONFIGURE A DHCP SERVER=
[[Image:dora.png|thumb|right|400px|The term '''DORA''' best describes how '''DHCP''' works. ]]
This lab will demonstrate setting up a DHCP server. The term '''DHCP''' stands for '''Dynamic Host Configuration Protocol'''. DHCP allows computers (eg. workstations, notebooks, smart-phones) to be automatically configured so that they can communicate over a network. This automatic configuration has gained popularity over the years, especially as the need for detecting and configuring portable computer devices increases. DHCP configuration allows for various setups including: '''Dynamic''', '''Automatic''', and '''Static''' allocation.
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The term '''DORA''' best describes how DHCP Works:
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|- valign="top"|width="8%" | <u>'''D'''</u>iscovery:|width="90%" |The client broadcasts a '''message''' (IP lease request) on a sub-network to '''discover''' available DHCP servers|- valign="top"|width="8%" | <u>'''O'''</u>ffer:|width="90%" |The DHCP server receives the request from the client, '''reserves an IP ADDRESS''' for the client and sends a '''DHCPOFFER'''|- valign="top"|width="8%" | <u>'''R'''</u>equest:|width="9%" |The DHCP server broadcasts a message '''request for acceptance''', but also notifies other DHCP server|- valign="top"|width="8%" | <u>'''A'''</u>cknowledgement:|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|}<br><br>== Part 1: Installation of a DHCP=={| width="40%" align="right" cellpadding="10"|- valign="top"|{{Admon/important note| Update 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 systems VMs)| It }}|}# Perform this section in your '''centos3''' VM.<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 advisable installed by default by the workstation installation.<br><br># To check that you have <b>dhclient</b> 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 <b>dhclient</b> package if it was not installed.# Issue the following command to perform a install the dhcp server package: <b><code><span style="color:#3366CC;font-size:1.2em;">yum updateinstall dhcp</span></code> on your host and </b># Enter the command to list all 3 VMthe files installed from the DHCP server package by 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 file for dhcpd.conf?# Copy the '''dhcpd.conf.example''' file to the '''/etc/dhcp''' directory making sure it is named: '''s/etc/dhcp/dhcpd.}}conf'''
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# Remain in your '''centos3''' VM for this section.# Study the man pages of <code>dhcpd<Edit '''/code>, <code>dhcpd.conf<etc/code>, <code>dhcp-options</code>, and <code>dhcpd.leases</code> conf''' for a second time.# View this file for existing subnet declarations. Note the syntax and make notes in your log book. In particular, look up the meaning directive for '''range''' and possible valuethe option for '''routers''' (sgateway).# Now, if any, add a new subnet delcaration for the following configuration options::your virtual network:* <codebr>broadcast-address</codebr>The network address is::* <code>default-lease-time<'''192.168.235.0/code>::* 255.255.255.0'''<codebr>max-lease-time</code> (How is this different range of host addresses should be from : '''51 to 60'''<codebr>default-lease-time</code>?gateway (routers)for the virtual network is::* '''192.168.235.1'''<codebr>domain-name</codebr>::* # Save your editing session, and exit the text editor.<codeol>domain-name-servers</codeli value="6">:Open another terminal window (ssh into centos3 from the centos host as user root) and issue the following command:* <codebr>fixed-address</codeb>::* <code>group</code>span style="color:#3366CC;font-size:* <code1.2em;">hardwaretail -f /var/log/messages</codespan>::* </code>host</codeb>::* <codebr>host-name<br>(This will show you the last lines of '''/var/code>::* <code>range<log/code>::* messages''' continue to display new lines as they are added to the log.)<code>routers</codebr>::* <codebr>subnet</codeli>::* <codeli>subnet-maskIn your original terminal prompt attempt to start the '''dhcpd''' service.</codeli><ol><li value="2"> Study You should see new lines being added to the sample <code>dhcpd.conf</code> messages file to see examples of how these options are used.</li>
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'''Answer Part 4 observations / questions in your lab log book.'''
=== Investigation 5INVESTIGATION 2: How do I test my dhcpd service on my virtual network?==OBTAINING LEASE & LEASE PERMANENT IP ADDRESS INFORMATION=
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'''Answer the Investigation 6 Part 1 observations / questions in your lab log book.'''
==Part 2: Configuring DHCP server to Continually Lease Same IP Address= Investigation 7: How can I lease the same address every time? ={|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>
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::: <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>
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'''Answer the Investigation 7 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?