Install DHCP Server on Ubuntu 22.04

This article is going to take you through on how to Install DHCP Server on Ubuntu 22.04. The DHCP Server is a network server that allocates IP addresses, default gateways, and other network information to client devices automatically. DHCP server uses standard protocol known as Dynamic Host Configuration Protocol(DHCP) to respond to broadcast queries by clients.

How to Install DHCP Server on Ubuntu 22.04

Install DHCP Server on Ubuntu 22.04

Update your packages.

sudo apt update

Then install DHCP Server using the command below.

sudo apt install isc-dhcp-server

Sample output

 Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following packages were automatically installed and are no longer required:
  fonts-open-sans gir1.2-gnomebluetooth-1.0
  i965-va-driver intel-media-va-driver kwayland-data
  libaacs0 libavcodec58 libavformat58 libavutil56
  libbdplus0 libbluray2 libchromaprint1 libcodec2-1.0
  libdouble-conversion3 libgme0 libgsm1 libigdgmm12
  libkf5waylandclient5 libmd4c0 libmfx1 libminizip1
  libmng2 libnorm1 libopenal-data libopenal1 libopenmpt0
  libpcre2-16-0 libpgm-5.3-0 libqrcodegencpp1
  libqt5core5a libqt5dbus5 libqt5gui5 libqt5network5
  libqt5svg5 libqt5waylandclient5 libqt5widgets5
  librabbitmq4 librlottie0-1 libshine3 libsndio7.0
  libsrt1.4-gnutls libssh-gcrypt-4 libswresample3
  libswscale5 libudfread0 libva-drm2 libva-x11-2 libva2
  libvdpau1 libx264-163 libxcb-record0
  libxcb-screensaver0 libxcb-xinerama0 libxcb-xinput0
  libxvidcore4 libzmq5 libzvbi-common libzvbi0
  mesa-va-drivers mesa-vdpau-drivers
  qt5-gtk-platformtheme qt5-image-formats-plugins
  qttranslations5-l10n va-driver-all vdpau-driver-all
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
  libirs-export161 libisccfg-export163
Suggested packages:
  isc-dhcp-server-ldap policycoreutils
The following NEW packages will be installed:
  isc-dhcp-server libirs-export161 libisccfg-export163
0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 528 kB of archives.
After this operation, 1,545 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://ke.archive.ubuntu.com/ubuntu jammy/main amd64 libisccfg-export163 amd64 1:9.11.19+dfsg-2.1ubuntu3 [53.0 kB]
Get:2 http://ke.archive.ubuntu.com/ubuntu jammy/main amd64 libirs-export161 amd64 1:9.11.19+dfsg-2.1ubuntu3 [20.0 kB]
Get:3 http://ke.archive.ubuntu.com/ubuntu jammy/main amd64 isc-dhcp-server amd64 4.4.1-2.3ubuntu2 [455 kB]
Fetched 528 kB in 0s (1,517 kB/s)

Configure DHCP Server on Ubuntu 22.04

To begin with configure to listen on an interface.
- You can configure your DHCP server by editing the config file located at /etc/default/isc-dhcp-server. Open the config file with text editor of your choice.

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

Then define your network interface as in the example below. After that save and close the file.
You can check your network interface using the command ip a.
Note that this is the interfaces that the DHCP server (dhcpd) serve should DHCP requests on. Clients will connect to this interface to get the IP addresses.

 INTERFACESv4="ens33"

If you have multiple interfaces, then you can define them space separated enclosed within the quote;

INTERFACESv4="ens33 ens34"

On my server, this is the interface that will be used to server DHCP requests;

ip a show dev ens33

4: ens33:  mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 08:00:27:40:84:d0 brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.1/24 brd 192.168.0.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::a00:27ff:fe40:84d0/64 scope link 
       valid_lft forever preferred_lft forever

Save and exit the file when done with configurations.
Start DHCP server using the following command.

sudo systemctl start isc-dhcp-server

Enable DHCP server to start on system boot.

systemctl enable isc-dhcp-server

Next, you can configure your DHCP server. The default config file is located at /etc/dhcp/dhcpd.conf To do that open the file using the command below.

sudo  nano /etc/dhcp/dhcpd.conf

Define your domain name and DNS nameservers, if applicable;

option domain-name "itnixpro.com";
option domain-name-servers ns1.itnixpro.com, ns2.itnixpro.com;

Define the default and maximum lease time;
- default-lease-time: is the lease time used if the client does not request a specific lease.
- max-lease-time: defines the longest lease that the server can allocate

default-lease-time 3600;
max-lease-time 43200;

Configure the DHCP server as official DHCP server for the local network by uncommenting the parameter, authoritative.

authoritative;

Configure DHCP server to send dhcp log messages to a different log file by uncommenting the line;

log-facility local7

Define the DHCP network IP range.
- IP range
- gateway/router address
- domain name servers
- domain names

subnet 192.168.0.0 netmask 255.255.255.0 {
 range 192.168.0.100 192.168.0.200;
 option routers 192.168.0.1;
 option domain-name "itnixpro.com"
 option domain-name-servers 192.168.0.1, 8.8.8.8;
}

And those are the only changes we will use in this setup.Save and exit the configuration file when done with configuration.

We enabled syslog logging. Thus, configure syslog to log DHCP events as follows;

echo "local7.* /var/log/dhcpd.log" | sudo tee /etc/rsyslog.d/51-dhcpd.conf

Now, to avoid DHCP double logging to /var/log/syslog and to /var/log/dhcpd.log, you need to make some changes to syslog logging by adding the line local7.none to facilities that logs to /var/log/syslog;

sed -i '/\/var\/log\/syslog/s/none/none,local7.none/' /etc/rsyslog.d/50-default.conf

The line should now look like;

grep '/var/log/syslog' /etc/rsyslog.d/50-default.conf

*.*;auth,authpriv.none,local7.none		-/var/log/syslog

Restart Rsyslog

sudo systemctl restart rsyslog

Open DHCP Server Ports on Firewall

Allow DHCP port on firewall.

sudo ufw allow  67/udp

Restart DHCP server to apply changes.

sudo systemctl restart isc-dhcp-server.service

DHCP server should be up and running, check status using the command below.

sudo systemctl status isc-dhcp-server

Sample output

● isc-dhcp-server.service - ISC DHCP IPv4 server
     Loaded: loaded (/lib/systemd/system/isc-dhcp-server.service; enabled; vendor preset: enabled)
     Active: active (running) since Wed 2022-04-27 18:25:42 EAT; 1s ago
       Docs: man:dhcpd(8)
   Main PID: 5781 (dhcpd)
      Tasks: 4 (limit: 2292)
     Memory: 4.5M
        CPU: 17ms
     CGroup: /system.slice/isc-dhcp-server.service
             └─5781 dhcpd -user dhcpd -group dhcpd -f -4 -pf /run/dhcp-server/dhcpd.pid -cf /etc/dhcp/dhcpd.conf ens33

Elb 27 18:25:42 dhcp.itnixpro.com dhcpd[5781]: For info, please visit https://www.isc.org/software/dhcp/
Elb 27 18:25:42 dhcp.itnixpro.com dhcpd[5781]: Wrote 0 leases to leases file.
Elb 27 18:25:42 dhcp.itnixpro.com sh[5781]: Wrote 0 leases to leases file.
Elb 27 18:25:43 dhcp.itnixpro.com dhcpd[5781]: Listening on LPF/ens33/08:00:27:40:84:d0/192.168.0.0/24
Elb 27 18:25:43 dhcp.itnixpro.com sh[5781]: Listening on LPF/ens33/08:00:27:40:84:d0/192.168.0.0/24
Elb 27 18:25:43 dhcp.itnixpro.com dhcpd[5781]: Sending on   LPF/ens33/08:00:27:40:84:d0/192.168.0.0/24
Elb 27 18:25:43 dhcp.itnixpro.com sh[5781]: Sending on   LPF/ens33/08:00:27:40:84:d0/192.168.0.0/24
Elb 27 18:25:43 dhcp.itnixpro.com dhcpd[5781]: Sending on   Socket/fallback/fallback-net
Elb 27 18:25:43 dhcp.itnixpro.com sh[5781]: Sending on   Socket/fallback/fallback-net
Elb 27 18:25:43 dhcp.itnixpro.com dhcpd[5781]: Server starting service.

Also check the logs;

tail -f /var/log/dhcpd.log

It’s a wrap! You have made it to the end of our article. Congrats! you have learned how to Install DHCP Server on Ubuntu 22.04.

Read more about DHCP protocol on the manpages.

You need to configure DHCP clients. Check the guide below;

How to Configure DHCP Client on Ubuntu 22.04

Install DHCP Server on Ubuntu 22.04

How to Install DHCP Server on Ubuntu 22.04