Hack The Sec-Leading Resource Of Linux Tutorial: DHCP-Server

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<u><span style="color: #990000;">Install DHCP on CentOs 7 / RHEL 7</span></u></h2>
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<span style="font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">DHCP Stands for Dynamic Host Configurations Protocol that is used to dynamically assign IP Addresses to Clients, on every device attached on network requires an IP Address to communicate with other devices.</span></span></div>
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<span style="font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">If you notice when you connect to a network and you get an IP address automatically that is given by <a href="http://www.hackthesec.co.in/search/label/DHCP-Server">DHCP Server</a>.</span></span></div>
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<b><u><span style="color: #0b5394;">Step – 1</span></u></b></div>
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Open the terminal window and install DHCP package using yum command.</div>
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<pre style="background-attachment: scroll; background-clip: initial; background-color: #3c3c3c; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white; font-size: large;"><span style="line-height: 20.8px;">yum install dhcp -y</span></span></pre>
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<span style="color: #0b5394; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;"><b><u>Step - 2</u></b></span></span></div>
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<span style="font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">Edit the configuration file.</span></span></div>
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<pre style="background-attachment: scroll; background-clip: initial; background-color: #3c3c3c; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white; font-size: large;"><span style="line-height: 20.8px;">vi /etc/etc/dhcp/dhcpd.conf</span></span></pre>
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<span style="font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">Copy and paste below code into '<b>/etc/dhcp/dhcpd.conf</b>' file, and change according to your desired settings.</span></span></div>
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<pre style="background-color: whitesmoke; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 4px; border: 1px solid rgb(204, 204, 204); box-sizing: border-box; margin-bottom: 10px; overflow: auto; padding: 9.5px; word-break: break-all; word-wrap: break-word;"><span style="color: #333333; font-family: Menlo, Monaco, Consolas, 'Courier New', monospace; font-size: 13px; line-height: 1.42857;"># DHCP Server Configuration file.
# see /usr/share/doc/dhcp*/dhcpd.conf.example
# see dhcpd.conf(5) man page
#
# Option definitions common to all supported networks
# Specify domain name
option domain-name “hackthesec.co.in”;
# Specify name server’s hostname or IP address
option domain-name-servers 192.168.1.1;
# Default lease time
default-lease-time 600;
# Max lease time
max-lease-time 7200;
# This DHCP server Authoritative server in the Network.
authoritative;
subnet 192.168.1.0 netmask 255.255.255.0 {# Specify the range of lease IP address
range dynamic-bootp 192.168.1.11 192.168.1.100;
# Specify broadcast address
option broadcast-address 192.168.1.255;
# Specify default gateway
option routers 192.168.1.1;
}</span><span style="font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px; white-space: normal;">
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<span style="font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">Now Save and Exit the file.</span></span></div>
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<pre style="background-attachment: scroll; background-clip: initial; background-color: #3c3c3c; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white; font-size: large;"><span style="line-height: 20.8px;">:wq</span></span></pre>
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<span style="color: #0b5394; font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;"><b><u>Step - 3</u></b></span></span></div>
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<span style="font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">Now its time to Enable and start the DHCP Service.</span></span></div>
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<pre style="background-attachment: scroll; background-clip: initial; background-color: #3c3c3c; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white; font-size: large;"><span style="line-height: 20.8px;">systemctl enable dhcpd</span></span></pre>
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<span style="font-family: verdana, geneva, sans-serif;"><span style="font-size: 15px; line-height: 26px;">If you didn’t miss anything clients machines on your network now able to get automatic ip addresses from your DHCP server.</span></span></div>
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So, setup your client machine on "Obtain an IP Address Automatically" it should get an automatic ip addresses from the specified range in the <a href="http://www.hackthesec.co.in/search/label/DHCP">DHCP </a>server.</div>
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<a href="http://www.hackthesec.co.in/">www.hackthesec.co.in</a></div>
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How to Install DHCP on CentOs 7 / RHEL 7

Install DHCP on CentOs 7 / RHEL 7 DHCP Stands for Dynamic Host Configurations Protocol that is used to dynamically assign IP Addresses ...

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<span style="color: #990000;"><i><u>Setup DHCP server on ubuntu 14.04</u></i></span></h1>
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<span style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 16px; line-height: 19.8400001525879px;">The Dynamic Host Configuration Protocol (</span><b style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 16px; line-height: 19.8400001525879px;"><a href="http://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol">DHCP</a></b><span style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 16px; line-height: 19.8400001525879px;">) is a network protocol used to assign IP</span></div>
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<span style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 16px; line-height: 19.8400001525879px;"> addresses and provide configuration information to devices such as </span><b style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 16px; line-height: 19.8400001525879px;">servers</b><span style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 16px; line-height: 19.8400001525879px;">, desktops, or </span></div>
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<span style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 16px; line-height: 19.8400001525879px;">mobile devices, so they can communicate on a network using the Internet Protocol (IP).</span></div>
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<span style="color: #0b5394;">DHCP server on <a href="http://www.hackthesec.co.in/search/label/Ubuntu">ubuntu</a> 14.04</span></h2>
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<span style="color: #222222;">Before installation, Make sure you have assigned static IP to the server.</span><br /><strong style="color: #222222;">Step 1 :</strong><span style="color: #222222;"> Issue the below command to update repository.</span><br /><code style="background-color: #0e0e0e; border-radius: 5px; display: block; font-family: Verdana, 'MS Sans Serif', sans-serif, serif; font-size: 14px; line-height: 25px; padding: 4px;"><span style="color: white;">root@hackthesec:~$ sudo apt-get </span><span style="color: lime;">update</span></code><br /><strong style="color: #222222;">Step 2 </strong><strong style="color: #222222;">:</strong><span style="color: #222222;">  Now install <b>isc-dhcp-server</b> package and dependencies.</span><br /><code style="background-color: #0e0e0e; border-radius: 5px; display: block; font-family: Verdana, 'MS Sans Serif', sans-serif, serif; font-size: 14px; line-height: 25px; padding: 4px;"><span style="color: white;">root@hackthesec:~$ sudo </span><span style="color: lime;">apt-get install</span><span style="color: white;"> isc-dhcp-server -y</span></code><br /><strong style="color: #222222;">Step 3 </strong><strong style="color: #222222;">:</strong><span style="color: #222222;">  After installing, open </span><strong style="color: #222222;">/etc/default/isc-dhcp-server</strong><span style="color: #222222;"> file and assign interface.</span><br /><code style="background-color: #0e0e0e; border-radius: 5px; display: block; font-family: Verdana, 'MS Sans Serif', sans-serif, serif; font-size: 14px; line-height: 25px; padding: 4px;"><span style="color: white;">root@hackthesec:~$ sudo nano /etc/default/</span><span style="color: lime;">isc-dhcp-server</span><br /><span style="color: white;">INTERFACES="</span><span style="color: lime;">eth0</span><span style="color: white;">"</span></code><br /><strong style="color: #222222;">Step 4 </strong><strong style="color: #222222;">:</strong><span style="color: #222222;">  We need to define below values in </span><span style="color: red;"><strong>dhcpd.conf</strong> </span><span style="color: #222222;">file located in </span><strong><span style="color: red;">/etc/dhcp/ </span></strong><span style="color: #222222;">directory.</span><br /><strong><u><span style="color: #0b5394;">Example:</span></u></strong></div>
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<code style="background-color: #0e0e0e; border-radius: 5px; display: block; padding: 4px;"><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">Network : 192.168.100.0/24</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">Range : 192.168.100.20 ( Starting IP ) – 192.168.100.100 ( Ending IP )</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">Gateway : 192.168.100.1</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">Primary DNS : 192.168.100.5</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">Sec DNS : 8.8.8.8</span></span></code></code></div>
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<span style="color: #222222; font-family: Trebuchet, 'Trebuchet MS', Arial, Verdana, sans-serif; font-size: 16px; line-height: 30px;">Take backup copy before making changes to the original file .Better rename the file and create a new one .</span><br /><code style="background-color: #0e0e0e; border-radius: 5px; display: block; font-family: Verdana, 'MS Sans Serif', sans-serif, serif; font-size: 14px; line-height: 25px; padding: 4px;"><span style="color: white;">root@hackthesec:~$ sudo mv /etc/dhcp/</span><span style="color: lime;">dhcpd</span><span style="color: white;">.conf /etc/dhcp/</span><span style="color: lime;">dhcpd.conf.org</span></code><br /><code style="background-color: #0e0e0e; border-radius: 5px; display: block; font-family: Verdana, 'MS Sans Serif', sans-serif, serif; font-size: 14px; line-height: 25px; padding: 4px;"><span style="color: white;">root@hackthesec:~$ sudo nano </span><span style="color: lime;">/etc/dhcp/dhcpd.conf</span></code></div>
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<span style="color: #222222; font-family: Trebuchet, Trebuchet MS, Arial, Verdana, sans-serif; font-size: large;"><span style="line-height: 30px;">and add the below code after making changes as per your network values.</span></span><br />
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<code style="background-color: #0e0e0e; border-radius: 5px; display: block; padding: 4px;"><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">default-lease-time 600;</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">max-lease-time 7200;</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"># If this DHCP server is the official DHCP server for the local</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"># network, the authoritative directive should be uncommented.</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">authoritative;</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"># Use this to send dhcp log messages to a different log file (you also</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"># have to hack syslog.conf to complete the redirection).</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">log-facility local7;</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"><br /></span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">subnet 192.168.100.0 netmask 255.255.255.0 {  #network</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"><span class="Apple-tab-span" style="white-space: pre;"> </span>range 192.168.100.20 192.168.100.100; # Range</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"><span class="Apple-tab-span" style="white-space: pre;"> </span>option domain-name-servers 192.168.100.5, 8.8.8.8; #Pri DNS , Sec DNS</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"><span class="Apple-tab-span" style="white-space: pre;"> </span>option domain-name "hackthesec.co.in"; #Domain name </span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"><span class="Apple-tab-span" style="white-space: pre;"> </span>option routers 192.168.100.1; #Gateway</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"><span class="Apple-tab-span" style="white-space: pre;"> </span>option broadcast-address 192.168.100.255; #Broadcast</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"><span class="Apple-tab-span" style="white-space: pre;"> </span>default-lease-time 600;</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;"><span class="Apple-tab-span" style="white-space: pre;"> </span>max-lease-time 7200;</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">}</span></span></code></code></div>
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<strong style="color: #222222;">Step 5 »</strong><span style="color: #222222;"> Now start/restart dhcp service using the below command.</span><br /><code style="background-color: #0e0e0e; border-radius: 5px; display: block; font-family: Verdana, 'MS Sans Serif', sans-serif, serif; font-size: 14px; line-height: 25px; padding: 4px;"><span style="color: white;">root@hackthesec:~$ sudo service </span><span style="color: lime;">isc-dhcp-server restart</span></code></div>
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<u>Address Reservation</u></h3>
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Sometimes you need to reserve IP to some devices like printers, camera, linux machines etc.<br />In this case, first you need to find MAC Address of that device and define values in that particular subnet.<br />For example, Printer with <b>00:DD:HD:66:55:9B</b> MAC Address has to be assigned with 192.168.100.50 IP. For this, you need to add code like below to that subnet.</div>
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<code style="background-color: #0e0e0e; border-radius: 5px; display: block; padding: 4px;"><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: lime; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">subnet 192.168.100.0 netmask 255.255.255.0 {  #network</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">       -  -   -    -   -  </span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">       max-lease-time 7200;</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">     host printer-finance {</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">                hardware ethernet 00:DD:HD:66:55:9B; </span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">                fixed-address 192.168.100.50;</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">        }</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">       host cam-gate {</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">                hardware ethernet 00:KK:HD:44:55:22;</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">                fixed-address 192.168.100.90;</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">        }</span></span></code><code style="border-radius: 5px; display: block; padding: 4px;"><span style="color: white; font-family: Verdana, MS Sans Serif, sans-serif, serif;"><span style="font-size: 14px; line-height: 25px;">}</span></span></code></code></div>
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<span style="color: #222222;">And restart DHCP service.</span><br /><code style="background-color: #0e0e0e; border-radius: 5px; display: block; font-family: Verdana, 'MS Sans Serif', sans-serif, serif; font-size: 14px; line-height: 25px; padding: 4px;"><span style="color: white;">root@hackthesec:~$ sudo service </span><span style="color: lime;">isc-dhcp-server</span><span style="color: white;"> restart</span></code><pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); color: white; font-size: 12px; line-height: 1.3em; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><a href="http://www.hackthesec.co.in/" style="color: #999999; text-decoration: none;" target="_blank">Hack The Security</a>
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How to Setup DHCP server on ubuntu 14.04

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