How to install and configure a DHCP server in Ubuntu 12.04?

I need a step-by-step tutorial if somebody has one.

up vote 51 down vote accepted

The first thing You need to do is install the packages we need.

Open up a terminal and type:

sudo apt-get install isc-dhcp-server

There are two main files /etc/default/isc-dhcp-server and /etc/dhcp/dhcpd.conf which we will need to configure so lets take the first.

Open up a terminal and using your favorite text editor type:

sudo vim /etc/default/isc-dhcp-server

You should get the following:

#Defaults for dhcp initscript
#sourced by /etc/init.d/dhcp
#installed at /etc/default/isc-dhcp-server by the maintainer scripts
#
#This is a POSIX shell fragment
#
#On what interfaces should the DHCP server (dhcpd) serve DHCP requests"
#Separate multiple interfaces with spaces, e.g. “eth0 eth1".
INTERFACES="eth0"

Replace eth0 above with the name of your network interface that you want the server to lease addresses on. Onto the next file.

Open up a terminal and type:

sudo vim /etc/dhcp/dhcpd.conf

which should give you the output below.

#
#Sample configuration file for ISC dhcpd for Debian
#
#Attention: If /etc/ltsp/dhcpd.conf exists, that will be used as
#configuration file instead of this file.
#
#
....
option domain-name “example.org”;
option domain-name-servers ns1.example.org, ns2.example.org;
option domain-name “comtech.com”;
default-lease-time 600;
max-lease-time 7200;
log-facility local7;
subnet 10.0.0.0 netmask 255.255.255.0 {
range 10.0.0.150 10.0.0.253;
option routers 10.0.0.2;
option subnet-mask 255.255.255.0;
option broadcast-address 10.0.0.254;
option domain-name-servers 10.0.0.1, 10.0.0.2;
option ntp-servers 10.0.0.1;
option netbios-name-servers 10.0.0.1;
option netbios-node-type 8;
 ......
}

This needs a little bit of explaining.

  1. Adjust your settings according to your network requirements.
  2. The option domain name is your dns zone name. For example mine is set to comtech.com.
  3. Range should be the range of ip addresses that you want the server to give out to clients.

Now restart the dhcp service by typing:

sudo service isc-dhcp-server restart

Thats it!! Your dhcp server should be running, however it is best to check. Open up a terminal and type:

sudo netstat -uap

which will show you something like the following (look for dhcpd, nmbd, and named):

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address State PID/Program name
udp        0      0 10.0.0.255:netbios-dgm  *:*                   1016/nmbd
udp        0      0 10.0.0.255:netbios-ns   *:*                   1016/nmbd
udp        0      0 *:bootps                *:*                   4525/dhcpd
udp        0      0 *:netbios-dgm           *:*                   1016/nmbd
udp        0      0 *:netbios-ns            *:*                   1016/nmbd
udp        0      0 chris-desktop:domain    *:*                   1273/named
udp        0      0 chris-desktop.lo:domain *:*                   1273/named
udp        0      0 chris-deskt:netbios-dgm *:*                   1016/nmbd
udp        0      0 chris-deskto:netbios-ns *:*                   1016/nmbd
udp6       0      0 [::]:domain             [::]:*                1273/named
  • 1
    Just a word of caution, make sure to use /etc/dhcp/dhcpd.conf and not /etc/dhcp3/dhcpd.conf – puk Nov 14 '13 at 23:09
  • 1
    When I restart the service this message is shown: stop: Unknown instance: isc-dhcp-server start/running, process 3027. I am not able to start the service. I use Ubuntu 13.10. – JJD Apr 13 '14 at 10:53
  • 1
    good . but make sure you've assigned static IP b4 starting DHCP service – krizna Nov 24 '14 at 10:05
  • This is not so hard, but using dnsmasq is easier if you ask me. – Reinier Post Jun 2 '17 at 21:43

Additional things can be included in the accepted answer

  1. Assign static IP before starting isc-dhcp-server service .

  2. You can reserve IP for devices like printers and linux machines by adding MAC id in the below format inside the particular subnet.

    ------
    host bla1 { 
            hardware ethernet DD:GH:DF:E5:F7:D7;
            fixed-address 10.0.0.10;
    }
    ----
    

    Dhcp3-server Community Wiki

    Ubuntu DHCP server

From the Ubuntu community page dhcp3-server by Contributors to the Ubuntu documentation wiki:

Dynamic Host Configuration Protocol (DHCP)

The Dynamic Host Configuration Protocol (DHCP) is a network service that enables host computers to be automatically assigned settings from a server as opposed to manually configuring each network host. Computers configured to be DHCP clients have no control over the settings they receive from the DHCP server, and the configuration is transparent to the computer's user.

Installation

At a terminal prompt, enter the following command to install dhcpd:

sudo apt-get install dhcp3-server

You will probably need to change the default configuration by editing /etc/dhcp3/dhcpd.conf to suit your needs and particular configuration.

You also need to edit /etc/default/dhcp3-server to specify the interfaces dhcpd should listen to. By default it listens to eth0.

Configuration

The error message the installation ends with might be a little confusing, but the following steps will help you configure the service:

Most commonly, what you want to do is assign an IP address randomly. This can be done with settings as follows:

nano -w /etc/dhcp3/dhcpd.conf
# Sample /etc/dhcpd.conf
# (add your comments here) 
default-lease-time 600;
max-lease-time 7200;
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.1.255;
option routers 192.168.1.254;
option domain-name-servers 192.168.1.1, 192.168.1.2;
option domain-name "mydomain.example";

subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.10 192.168.1.100;
range 192.168.1.150 192.168.1.200;
} 

This will result in the DHCP server giving a client an IP address from the range 192.168.1.10-192.168.1.100 or 192.168.1.150-192.168.1.200. It will lease an IP address for 600 seconds if the client doesn't ask for a specific time frame. Otherwise the maximum (allowed) lease will be 7200 seconds. The server will also "advise" the client that it should use 255.255.255.0 as its subnet mask, 192.168.1.255 as its broadcast address, 192.168.1.254 as the router/gateway and 192.168.1.1 and 192.168.1.2 as its DNS servers.

If you need to specify a WINS server for your Windows clients, you will need to include the netbios-name-servers option, e.g.

nano -w /etc/default/dhcp3-server
option netbios-name-servers 192.168.1.1; 

dhcp3-server and multiple interfaces

multiple interfaces example

Interface

nano -w /etc/network/interfaces
auto lo
iface lo inet loopback

mapping hotplug
        script grep
        map eth1

iface eth1 inet dhcp

auto eth0
iface eth0 inet static
    address 10.152.187.1
    netmask 255.255.255.0

auto wlan0
  iface wlan0 inet static
    address 192.168.1.1
    netmask 255.255.255.0
    up     /sbin/iwconfig wlan0 mode TTTTTT && /sbin/iwconfig wlan0 enc
restricted && /sbin/iwconfig wlan0 key [Y] XXXXXXXX && /sbin/iwconfig
wlan0 essid SSSSSSSS

auto eth1

Select Interface card

nano -w /etc/default/dhcp3-server
INTERFACES="wlan0 eth0"

Configure Subnet

nano -w /etc/dhcp3/dhcpd.conf
ddns-update-style none;
log-facility local7;

subnet 192.168.1.0 netmask 255.255.255.0 {

        option routers                  192.168.1.1;
        option subnet-mask              255.255.255.0;
        option broadcast-address        192.168.1.255;
        option domain-name-servers      194.168.4.100;
        option ntp-servers              192.168.1.1;
        option netbios-name-servers     192.168.1.1;
        option netbios-node-type 2;
        default-lease-time 86400;
        max-lease-time 86400;

        host bla1 {
                hardware ethernet DD:GH:DF:E5:F7:D7;
                fixed-address 192.168.1.2;
        }
        host bla2 {
                hardware ethernet 00:JJ:YU:38:AC:45;
                fixed-address 192.168.1.20;
        }
}

subnet  10.152.187.0 netmask 255.255.255.0 {

        option routers                  10.152.187.1;
        option subnet-mask              255.255.255.0;
        option broadcast-address        10.152.187.255;
        option domain-name-servers      194.168.4.100;
        option ntp-servers              10.152.187.1;
        option netbios-name-servers     10.152.187.1;
        option netbios-node-type 2;

        default-lease-time 86400;
        max-lease-time 86400;

        host bla3 {
                hardware ethernet 00:KK:HD:66:55:9B;
                fixed-address 10.152.187.2;
        }
}

Check Route

ip route
192.168.1.0/24 dev wlan0  scope link
82.16.TT.0/24 dev eth1  scope link
10.152.187.0/24 dev eth0  scope link
default via 82.16.TT.UU dev eth1

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