How to Install and Configure Dnsmasq with Web Frontend on RHEL 9

/ Christopher Paquin

In this post we are going to install and configure dnsmasq with a simple webUI acting as a front end for our less technical users. Our goal is to simplify dns in our lab sandboxes, and keep users from directly modifying our dnsmasq config files.

Installation

First we need to install dnsmasq.

# dnf -y install dnsmasq

Now lets enable and start the service. We will also check the status of the service to ensure that we do not have any issues with the default config.

# systemctl start dnsmasq
# systemctl enable dnsmasq
# systemctl status dnsmasq

Configuration

Next let’s make a backup of the default configuration file before we start making modification. 

cp /etc/dnsmasq.conf /etc/dnsmasq.conf.orig

I made the following modifications.

  1. listen-address is the loopback and our routable ip address
  2. expand-hosts, we uncomment this in order to allow dnsmasq to automatically expand the hostnames to fully qualified domain names
  3. domain – this is the local domain that we will serve via dnsmasq
  4. dhcp-range – this is the range of IP addresses that dnsmasq is allowed to hand out
interface=enp1s0
listen-address=127.0.0.1,192.168.65.7
expand-hosts
domain=sandbox3.localdomain
dhcp-range=192.168.65.20,192.168.65.40,255.255.255.128,12h

Next we check our config file for any errors

# dnsmasq --test
dnsmasq: syntax check OK.

Now lets restart dnsmasq

# systemctl restart dnsmasq

Firewall Config

Now we need to modify firewalld

[root@dns ~]#  firewall-cmd --add-service=dns --permanent
success
[root@dns ~]# firewall-cmd --add-service=dhcp --permanent
success
[root@dns ~]# firewall-cmd --reload
success

Testing

I prefer to use nslookup for testing, so lets install it

# dnf -y install bind-utils

Now let’s make sure we are able to resolve addresses, using our local instance of dnsmasq. 

# nslookup
> server localhost
Default server: localhost
Address: ::1#53
Default server: localhost
Address: 127.0.0.1#53
> google.com
Server:		localhost
Address:	::1#53

Non-authoritative answer:
Name:	google.com
Address: 142.251.40.174
Name:	google.com
Address: 2607:f8b0:4006:821::200e

Install and Configure the Webui

For the webui – we are going to use a simple one that I found via the link below. https://github.com/akivajp/dnsmasq-webconf

First, we need to install git and pip

# dnf -y install git
# dnf -y install pip

Then we follow the directions which I will repeat here. 

# mkdir -p ~/git && cd ~/git
# git clone https://github.com/akivajp/dnsmasq-webconf.git

Then we use pip to install jinja2

# pip install --user bottle jinja2

Now change directory

# cd dnsmasq-webconf/

We now need to poke a hole for http traffic in our local firewall

# firewall-cmd --add-service=http --permanent
# firewall-cmd --reload

Now start the front end

#  python ~/git/dnsmasq-webconf/app/index.py 80 --leases /var/lib/dnsmasq/dnsmasq.leases --hosts /etc/hosts --config /etc/dnsmasq.conf

Creating a Service

So far we have dnsmasq configured and running, and we have installed a web front end and have been able to start it on the command line. Now we need to configure the front end to start as a service when the OS boots. So we now need to turn the webUI into a systemd service.

First we create the following service file

# vi /etc/systemd/system/dnsmasq-webconf.service

The contents of which are below. Note that we have modified relative paths to be absolute paths.

[Unit]
Description=DNSMasq WebConf
After=network.target

[Service]
ExecStart=/usr/bin/python3 /root/git/dnsmasq-webconf/app/index.py 80 --leases /var/lib/dnsmasq/dnsmasq.leases --hosts /etc/hosts --config /etc/dnsmasq.conf
Restart=always
User=root
WorkingDirectory=/root/git/dnsmasq-webconf/app
StandardOutput=journal
StandardError=journal

[Install]
WantedBy=multi-user.target

Now we need to reload systemd

# systemctl daemon-reload

Now we can start the service

# systemctl start dnsmasq-webconf.service

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