build_dnsmasq_server.sh

#!/usr/bin/bash

# This script was ran on Ubuntu 20.04. 

# Check for root
if [ "$EUID" -ne 0 ]
  then
    echo "Please run as root"
    echo "USAGE: sudo build-dnsmasq-server.sh"
  exit
fi

# Checking / installing net-tools
echo -e "\nInstalling Net Tools\n"
apt-get install net-tools -y
echo "\nNet Tools installed / updated.\n"

# systemd.resolved handler
echo -e "\nStopping systemd.resolved\n"
systemctl stop systemd-resolved
echo -e "systemd.resolved stopped.  Preventing autostart\n"
update-rc.d systemd-resolved disable
echo -e "systemd.resolved stopped from autostarting at boot"

# Install dnsmasq
echo -e "Installing DNSMASQ\n"
apt-get install dnsmasq -y
echo -e "DNSMASQ installed / updated\n\n"

# Obtaining Server IP
ip_address=$(/sbin/ifconfig | sed -n '2 p' | awk '{print $2}')
host_name=$(hostname)
echo "Determined IP Address to be: "  $ip_address

# Create hosts file base
hostData="
127.0.0.1 localhost\n
$ip_address $host_name\n
\n
# The following lines are desirable for IPv6 capable hosts \n
::1     ip6-localhost ip6-loopback \n
fe00::0 ip6-localnet \n
ff00::0 ip6-mcastprefix \n
ff02::1 ip6-allnodes \n
ff02::2 ip6-allrouters \n
"

mv /etc/hosts /etc/hosts.bak
echo -e "Removing existing hosts file at /etc/hosts\n"
rm -rf /etc/hosts
echo -e "Creating new hosts file at /etc/hosts\n"
> /etc/hosts
echo -e $hostData > /etc/hosts
echo -e "Hosts file creation successful\n\n"

# Create new resolv.conf
echo -e "Updating /etc/resolv.conf"
mv /etc/resolv.conf /etc/resolv.conf.bak
> /etc/resolv.conf
echo "nameserver 127.0.0.1" > /etc/resolv.conf
echo -e "Updated: resolv.conf\n"

# Backup original dnsmasq config
echo -e "Backing original dnsmasq configuration /etc/dnsmasq.conf to /etc/dnsmasq.conf.bak\n"
mv etc/dnsmasq.conf /etc/dnsmasq.conf.bak
echo -e "Configuration backed up.\n"
echo -e "Creating new dnsmasq.conf in /etc\n"

dnsmasqconf="
# Global settings\n
domain-needed \n
bogus-priv \n
no-resolv \n
expand-hosts \n
filterwin2k \n\n

# Upstream nameservers\n
server=8.8.4.4        \n
server=8.8.8.8        \n\n

# domain name       \n
domain=home.network  \n
local=/home.network/  \n\n

listen-address=127.0.0.1  \n
listen-address=$ip_address  \n"

echo -e $dnsmasqconf > /etc/dnsmasq.conf
echo -e "/etc/dnsmasq.conf created\n"

systemctl restart dnsmasq