How to Configure DHCP Server on Ubuntu 22.04 Step-by-Step
Published on: January 8, 2023 by Pradeep Kumar

Hello techies, in this post we will show you how to configure DHCP server on 
Ubuntu 22.04 LTS step-by-step.

DHCP stands for Dynamic Host Configuration Protocol, it works on client -server 
architecture. DHCP server assign IPv4 and IPv6 automatically to clients 
(computers) on the network. DHCP Server offers a lease of IP address to client,
if the clients request IP address and DHCP acknowledge it then client will get 
IP address for the lease time. If the lease time expires and clients wants to 
se the same IP address, then it must request IP address to DHCP server again.


Prerequisites


Pre-Installed Ubuntu 22.04 LTS
Sudo User with admin rights
Internet Connectivity or locally configured Repository
Two Ethernet Cards (1st for access management & 2nd will used for DHCP 
server)

Lab Setup:

I am using two VMs for Lab setup. 1st VM is Ubuntu 22.04 which will configured 
as DHCP server and 2nd VM is RHEL 9, which will work as client and will get IP 
address from DHCP server automatically.

Ubuntu 22.04 LTS has two Lan cards (NICs)

eth0 (192.168.1.204) – It will used for access management and internet
connectivity
eth1 (192.168.56.4)– It will be used for DHCP, we will expose the DHCP 
subnet on this interface.


RHEL 9 VM has one NIC eth0 which will request for DHCP IP address. This NIC
should be mapped to DHCP subnet VLAN.

Without any further delay, let’s jump into the installation steps.

1 ) Update Package Index


Login to Ubuntu 22.04 system and run beneath apt command to update package index

$ sudo apt update


2) Install DHCP Server and its dependencies


Run following apt command to install DHCP server and its dependent packages.

$ sudo apt install isc-dhcp-server -y


Install-DHCP-Server-apt-command


3) Configure DHCP Server


Edit /etc/default/isc-dhcp-server file and mention the interface on which DHCP 
would be running. In my case it is eth1

$ sudo vi /etc/default/isc-dhcp-server
----
INTERFACESv4="eth1"
---- 


Interface-DHCP-Server-Ubuntu-Linux

Save and close the file.

Now, edit main dhcp configuration file “/etc/dhcp/dhcpd.conf” and 
uncomment & set the following parameters, Comment out the domain name server
parameters as we are not using any DNS server,

#option domain-name "example.org";
#option domain-name-servers ns1.example.org, ns2.example.org;

Uncomment
authoritative;

Add the subnet and IP address range to be used for DHCP Server. Also specify 
the ip address of eth1 interface as routers.

subnet 192.168.56.0 netmask 255.255.255.0 
{
	range 192.168.56.20 192.168.56.120;
	option routers 192.168.56.4;
}

Save and exit the file


DHCP-Server-Config-File-Ubuntu

Start and enable dhcp server service using following commands,

$ sudo systemctl start isc-dhcp-server
$ sudo systemctl enable isc-dhcp-server

Verify dhcp server service status, run

$ sudo systemctl status isc-dhcp-server


DHCP-Server-Service-Ubuntu-Linux

Output above confirms that DHCP server service is up and running. Now, it’s time
to configure client so that it can get IP address from this DHCP server automatically.


4) Configure DHCP Client


In our case, our DHCP client is a RHEL 9 machine, So login to it and configure 
interface eth0 so that it requests for DHCP IP over network.

$ sudo nmtui

Edit eth0 interface and set IPv4 Configuration as “Automatic”


Automatic-ipv4-nmtui-rhel

Click OK and then deactivate and activate the connection to make the changes 
into effect.

Verify the IP address, run below ip command

$ ip add show eth0


RHEL-DHCP-IP-Address-Interface

Head back to DHCP server and see the leased ip address, run following cat command


To get manufacturer names please download 
http://standards.ieee.org/regauth/oui/oui.txt to /usr/local/etc/oui.txt
Reading leases from /var/lib/dhcp/dhcpd.leases

dhcp-lease-list

MAC                IP              hostname       valid until    
manufacturer
====================================================
========================
8c:49:62:02:c6:97  192.168.0.130   RokuUltra-Den  2023-04-03 18:00:11 -NA-
b8:2c:a0:0c:d6:1e  192.168.0.100   AlarmSys0CD61E 2023-04-03 18:00:06 -NA-
c8:f0:9e:9b:c4:d8  192.168.0.137   esp32-arduino  2023-04-03 17:57:37 -NA-
ec:8a:c4:cb:d5:25  192.168.0.109   -NA-           2023-04-03 17:56:40 -NA-

OR

$ cat /var/lib/dhcp/dhcpd.leases


DHCP-IP-Leasesd-Ubuntu

That’s all from this guide. I hope you have found it informative. Kindly do 
post your queries and feedback in below comments section.