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OPS235 Lab 8

2,583 bytes added, 19:22, 28 December 2019

URL change for lab files.

= LAB PREPARATION =

{{Admon/caution|DO NOT START THIS LAB BEFORE GETTING LABS 1-7 CHECKED OFF|'''This lab will change some system values that make previous lab checks fail. For best results, have your professor check off Labs 1-7 before proceeding.'''}}

===Overview===

[http://linux.die.net/man/8/dhcpd dhcpd]

[http://man7.org/linux/man-pages/man8/ifconfig.8.html ifconfig]

Managing Services

[http://www.dsm.fordham.edu/cgi-bin/man-cgi.pl?topic=systemctl systemctl]

Additional Utilities

[http://man7.org/linux/man-pages/man1/tail.1.html tail]

[http://www.centos.org/docs/5/html/Deployment_Guide-en-US/s1-dhcp-configuring-server.html Configuring a DHCP Server ]

|}

=INVESTIGATION 1: INSTALL AND CONFIGURE A DHCP SERVER=

|- valign="top"

|width="8%" | '''O'''ffer:

|width="40%" |The DHCP server receives the request from the client, '''reserves an IP ADDRESS''' for the client and sends a '''DHCPOFFER'''to the client.

|- valign="top"

|width="8%" | '''R'''equest:

|width="40%" |~~The~~ After receiving a '''DHCPOFFER''', the DHCP ~~server~~ client broadcasts a message '''request for acceptance''' ('''DHCPREQUEST''') to all DHCP servers and, ~~but also~~ in doing so, the DHCP client notifies ~~other~~ all DHCP serverswhich DHCP server this DHCP client is requesting acceptance from.

|- valign="top"

|width="8%" | '''A'''cknowledgement:

|width="40%" |The ~~client~~ DHCP server identified in the '''DHCPREQUEST''' sends a '''message of acceptance to the ~~server~~client'''~~. In turn,~~ and the client then receives from ~~the~~ that DHCP server a '''packet of information''' containing the lease duration and other configuration information.

|}

:'''Perform the following steps:'''

# ~~Perform this section in~~ Launch your c7host machine and your centos3 VM.# Switch to your '''centos3''' VM. 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.

# To check that you have dhclient installed, enter the command:

#:: <code>rpm -~~q dhclient~~qla dhcp</code># If ~~the package is not installed, you will get the message ''"package dhclient is not installed"'', otherwise~~there are no files displayed, ~~you will get the version information of the rpm package. Install the dhclient package if it was not installed.# Issue~~ then issue the following command to install the dhcp server package: <code>yum install dhcp</code># ~~Enter~~ Again, enter the command to list all the files installed from the DHCP server package by issuing the command: <code>rpm -qla dhcp</code># ~~which~~ Which 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: '''/etc/dhcp/dhcpd.conf'''

# Study the sample '''dhcpd.conf''' file to see examples of how these options are used.

# Edit '''/etc/dhcp/dhcpd.conf''' and examine the top section of the file.

# Below the comment labeled: '''"option definitions common to all supported networks"'''. Change the existing global options with the newer values shown below: '''option domain-name''' '''"ops235.org";''' '''option domain-name-servers''' '''192.168.235.1;''' '''default-lease-time''' '''1200;''' '''max-lease-time''' '''3600;''' '''Note:''' Any values for time are stated in seconds.

# View your editing sessions for typos (check for missing semicolons), then save and exit your editing session.

|}

=== Part 3: Configuring DHCP Server for Static IP Addresses===

# Now, add a new subnet delcaration for your virtual network: The network address is: '''192.168.235.0/255.255.255.0''' range of host addresses should be from: '''51 to 60''' default gateway (routers) for the virtual network is: '''192.168.235.1'''

# Save your editing session, and exit the text editor.

<ol><li value="6">Open another terminal window ('''Tip: ssh''' into your '''centos3''' VM from your '''c7host''' as '''root''') and issue the following command: <code>tail -f /var/log/messages</code> (This will show you the last lines of '''/var/log/messages''' continue to display new lines as they are added to the logfor confirmation and troubleshooting.) </li><li>In your ~~original~~ '''centos3''' terminal ~~prompt~~ , attempt to start the '''dhcpd''' service.</li>

<li>You should see new lines being added to the messages file.</li>

</ol>

<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(Hint: use a pipeline command using '''grep''' to detect the pattern: '''enabled'''). If it is not enabled, use the '''~~chkconfig~~systemctl''' command to enable the dhcpd service so it started automatically upon boot-up.</li>

</ol>

:'''Perform the following steps:'''

# Use your '''~~centos2~~centos1''' and '''centos3''' VMs for this section.

# On your '''centos3''' terminal window (via ssh from your c7hsot machine) make sure that the command tail -f /var/log/messages is running.

# On your '''~~centos2~~centos1''' VM, Graphically 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) ([http://zenit.senecac.on.ca/wiki/index.php/OPS235_Lab_6_-_CentOS7#Part_2:_Configuring_VM_Network_Setup_Graphically_.28system-config-network.29 Refer to Lab6, Investigation1, Part2]). Note: if you are configuring via command line, make certain to restart the network for ~~centos2~~centos1.# Logout and restart your '''~~centos2~~centos1''' VM.# Observe the messages that get logged from the tail -f command as your ~~centos2~~ centos1 VM starts. You should see output similar to the following: ::~~Mar 24 13~~Jun 27 22:2809:24 49 centos3 dhcpd: DHCPDISCOVER from 52:54:00:617c:0085:e7 13 via ~~eth2~~eth0::~~Mar 24 13~~Jun 27 22:2809:25 50 centos3 dhcpd: DHCPOFFER on 192.168.235.51 to 52:54:00:617c:0085:e7 13 (centos1) via ~~eth2~~eth0::~~Mar 24 13~~Jun 27 22:2809:25 50 centos3 dhcpd: DHCPREQUEST for 192.168.235.51 (192.168.235.13) from 52:54:00:617c:0085:e7 13 (centos1) via ~~eth2~~eth0::~~Mar 24 13~~Jun 27 22:2809:25 50 centos3 dhcpd: DHCPACK on 192.168.235.51 to 52:54:00:617c:0085:e7 13 (centos1) via ~~eth2~~eth0

<ol>

<li value="6">On your '''~~centos2~~centos1'''VM, ~~confirm~~ open a terminal, andconfirm the IP address assignment using <code>ifconfigeth0</code></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>

'''Answer INVESTIGATION 1 observations / questions in your lab log book.'''

=INVESTIGATION 2: OBTAINING LEASE & LEASE PERMANENT IP ADDRESS INFORMATION=

:'''Perform the following steps:'''

# Remain in your '''~~centos2~~centos1''' and '''centos3''' VMs for this section.# If your '''centos3''' DHCP server successfully issued the proper IP address configuration values to '''~~centos2~~centos1''', check the file called: '''/var/lib/dhcpd/dhcpd.leases''' in your '''centos3''' VM. You should get the similar contents:~~ ~~

:: lease 192.168.235.51 {

::    starts ~~5 2015~~1 2016/0706/~~10 17~~28 01:5707:3400;::    ends ~~5 2015~~1 2016/0706/~~10 18~~28 01:1727:3400;::    cltt ~~5 2015~~1 2016/0706/~~10 17~~28 01:5707:3400;::    binding state active;::    next binding state free;::    rewind binding state free;::    hardware ethernet 52:54:00:0eba:7d75:a4a8;:: }<ol><li value="3">On the client'''centos1''' check the contents of the /var/lib/dhclient directory. The files in this directory is where the dhclient stores its record of leases. '''NOTE:''' If there are no files, then in a shell as '''root''' in your '''centos1''' VM issue the command: <code>dhclient eth0</code> Then check to see if there is file containing lease information in that directory. You should get the similar contents: </li></ol>:: lease {::   interface "eth0";::   fixed-address 192.168.235.52;::   option subnet-mask 255.255.255.0;::   option routers 192.168.235.1;::   option dhcp-lease-time 1200;::   option dhcp-message-type 5;::   option domain-name-servers 192.168.235.1;::   option dhcp-server-identifier 192.168.235.13;::   option domain-name "ops235.org";::   renew 2 2016/06/28 02:23:06;::   rebind 2 2016/06/28 02:31:52;::   expire 2 2016/06/28 02:34:22;

:: }

<ol><li value="3">On the client '''centos2''' check the contents of the /var/lib/dhclient directory. The files in this directory is where the dhclient stores its record of leases. '''NOTE:''' If there are no files, then in a shell as root in your centos2 VM issue the command: <code>dhclient eth0</code> Then check to see if there is file containing lease information in that directory. </li>~~</ol>~~

'''Answer Part 1 observations / questions in your lab log book.'''

:'''Perform the following steps:'''

# Remain in your '''~~centos2~~centos1''' and '''cento3''' VMs for this section.

# Make certain that you are located in your '''centos3''' virtual machine.

# Edit the dchpd.conf file and make the following changes:<ul><li> Create a '''host ''' declaration with the name: '''centos1''' (tip: search for the key-word '''~~centos2~~"host"'''in the text editor to see an example). ~~Make sure you record the correct~~ <~~code~~/li><li>Set the '''hardware ethernet~~</code> setting that corresponds to~~ ''' option for the MAC address of the ~~interface in~~ eth0 on your '''~~centos2~~centos1'''VM.~~# Give it~~ </li><li>Set the '''fixed-address ''' option to the ip address: '''192.168.235.42'''<br/li></ul> '''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. <ol><li value="54">~~Start your~~ Restart the dhcpd service and test the address assignment by releasing your current address on '''~~centos2~~centos1''' and then requesting a new address. Use the following commands on '''~~centos2~~centos1''':</li>

</ol>

::: <code>ifdown ~~eth1~~eth0</code>::: <code>ifup ~~eth1~~eth0</code><ol><li value="65">Confirm that you received the fixed address you were supposed to.</li>

</ol>

:'''Perform the Following Steps:'''

#~~You~~ Make certain ALL of your '''centos1''' and '''centos3''' VMs are ~~~~running.# Switch to your '''c7host''' VM and '''su -''' into root.# Change to the '''~~NOT~~/root/bin'''directory.# Issue the Linux command: <code>wget https://ict.senecacollege.ca/~ops235/labs/lab8-check.bash</ucode> ~~required to download~~ # Give the '''lab8-check.bash''' file execute permissions (for the file owner).# Run the shell script and if any warnings, make fixes and re-run ~~a checking~~ shell script ~~for this final lab~~until you receive "congratulations" message. #Arrange proof of the following on the screen: <blockquote>✓ '''~~centos2~~centos1''' VM:<blockquote><ul><li>'''ifconfig eth0''' shows IP address '''192.168.235.42'''</li><li>DHCP client lease file</li></ul></blockquote>✓ '''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</li></ul></blockquote>✓ '''Lab8''' log-book filled out.

= Practice For Quizzes, Tests, Midterm & Final Exam =

[[Category:OPS235]]

[[Category:OPS235 Labs]]

[[Category:CentOS 7]]

[[Category:SSD2]]

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OPS235 Lab 8

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