Setting up a DHCP and local caching DNS Server with Dnsmasq on Ubuntu Server 18.04
This tutorial will show you how to install and configure Dnsmasq on Ubuntu Server 18.04 so that DNS requests by clients on your network are cached.
Dnsmasq is a free local DNS, DHCP and read-only TFTP server with support for BOOTP and PXE. It is lightweight while being capable of handling DNS and DHCP for at least a thousand clients.
Ubuntu Server 18.04 running on VMware Fusion was used to test the steps in this tutorial.
Before you begin, you’ll need to install Ubuntu Server 18.04 and configure it to use a static IP address. I’ve used
10.1.1.250 as the IP address throughout this guide.
Step 1: Update the hosts file
Once you’ve assigned a static IP address, edit the hostname in the
/etc/hosts file so that it resolves to the static IP. For example, if your hostname is
dnsmasq, edit the line:
This will allow clients to resolve the static IP of the DNS server.
Step 2: Install Dnsmasq
Run the following command to install Dnsmasq
sudo apt install dnsmasq
/etc/resolv.conf file so that it uses the local Dnsmasq server to resolve DNS requests.
echo "nameserver 127.0.0.1" | sudo tee /etc/resolv.conf
We’ll add the public DNS servers to the Dnsmaq config file in the next step.
Step 3: Configure DNS
The Dnsmasq configuration file on Ubuntu is located at
/etc/dnsmasq.conf. First we will create a backup by running the following command:
sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.bak
Now create a new file by running:
sudo vim /etc/dnsmasq.conf
Add the following contents to the file:
# Global settings domain-needed bogus-priv no-resolv expand-hosts filterwin2k # Upstream nameservers server=18.104.22.168 server=22.214.171.124 # domain name domain=vsphere.lab local=/vsphere.lab/ listen-address=127.0.0.1 listen-address=10.1.1.250
In the example config above, you might want to change the upstream nameservers from Googles to something different. You’ll also want to change the
listen-address options to suit your environment.
Save the file and apply the changes by restarting Dnsmasq with the following command:
sudo systemctl restart dnsmasq
Step 4: Configure DHCP
If you want to use the built-in DHCP server that comes with Dnsmaq, add the following to the config file and restart the service to apply the changes.
# DHCP options dhcp-range=10.1.1.11,10.1.1.249,12h dhcp-lease-max=100 dhcp-option=option:router,10.1.1.2 dhcp-option=option:dns-server,10.1.1.250 dhcp-option=option:netmask,255.255.255.0
You’ll want to adjust the IP settings and the range to suit your requirements.
How to assign fixed addresses
If you have any devices on your network that you’d like to fix the IP address of without having to change it to static in the device’s settings, you can do that by obtaining the MAC address of the device and adding an entry to the config like in the example below:
In this example, I’m fixing the device with the MAC address of
00:0C:29:D0:95:5E to the IP of
10.1.1.11 and giving it a hostname of
How to view DHCP Leases
If you want to see what DHCP leases have been created you can run the following command:
$ cat /var/lib/misc/dnsmasq.leases 1576643810 00:0c:29:d0:95:5e 10.1.1.201 testing ff:2b:94:34:c1:00:02:00:00:ab:11:80:ed:c7:78:b1:6f:4e:59 1576617132 00:0c:29:14:8a:0e 10.1.1.53 * *
This is can be a useful way of determining the MAC address of a machine before fixing its IP address.
How to add DNS Hosts
Hosts that are assigned via DHCP can already be resolved by other clients on your LAN, but if you want to add custom hosts to resolve, you can do it by adding them to the
For example, adding the following:
10.1.2.100 dev 10.1.2.101 staging
To the hosts file will resolve
10.1.2.100. It will also resolve
dev.vsphere.lab because of the
expand-hosts options set in the config file.
In this post, we learned how to install and configure Dnsmasq as a local DNS server. Using a local DNS server can speed up web response times when multiple devices on your network access the same domain name.
There’s more that Dnsmasq can do, such as network booting systems with BOOTP and PXE, or blocking domains by adding them to the hosts file with a local IP address.
In a future post, I will write a tutorial on how to use Dnsmasq to install Ubuntu over the network using PXE and the built-in TFTP server.