Script to run dnsmasq

run-dnsmasq.sh

#!/bin/bash

# These values need to be unique per host-only network
DNSMASQ_IFACE=${1-vboxnet0}         # The host-only network interface name (should show up with 'ifconfig -a')
NETWORK_PREFIX=${2-192.168.56}      # Network prefix must be unique per host

# You may want to customize the following: 
DNSMASQ_DOMAIN=${DNSMASQ_IFACE}     # Domain in which names assigned by dnsmasq appear, e.g. myvirtualbox1.vboxnet0
VBOX_HOST_IP="${NETWORK_PREFIX}.1"
VBOX_NETMASK=255.255.255.0
DNSMASQ_LEASE_TIME=10m
DNSMASQ_DHCP_RANGE="${NETWORK_PREFIX}.102,${NETWORK_PREFIX}.200,${DNSMASQ_LEASE_TIME}"
DNSMASQ_LEASEFILE="$TMPDIR/run-dnsmasq-leasefile.${DNSMASQ_DOMAIN}"
DNSMASQ_HOST_NAME="vbox-host.${DNSMASQ_DOMAIN}"

if ! which VBoxManage >/dev/null; then
  echo "VBoxManage command not found, is VirtualBox installed?"
  exit 1
fi

if ! which dnsmasq >/dev/null; then
  echo "dnsmasq command not found, is dnsmasq installed?"
  echo "Install with 'brew install dnsmasq'"
  exit 1
fi

# Check that the DNSMASQ_IFACE exists
if ! VBoxManage list hostonlyifs | grep -E 'Name:\s+'$DNSMASQ_IFACE > /dev/null; then
  echo "Host-only interface not found: $DNSMASQ_IFACE, create with 'VBoxManage hostonlyif create'"
  # Note that VirtualBox only supports interfaces with names vboxnet0, vboxnet1, ...
  # which it creates sequentially, therefore its difficult to autmatically create the required
  # interface in a script, rather bail out here let the user do it manually...
  exit 1
fi

# Disable VirtualBox built-in DHCP server
VBoxManage dhcpserver remove --ifname "$DNSMASQ_IFACE" 2>&1 | grep -v 'DHCP server does not exist'

# Configure the host IP address
VBoxManage hostonlyif ipconfig "$DNSMASQ_IFACE" --ip "$VBOX_HOST_IP" --netmask "$VBOX_NETMASK"

echo "nameserver $VBOX_HOST_IP" | sudo tee "/etc/resolver/${DNSMASQ_DOMAIN}" > /dev/null

echo "Running dnsmasq..."
sudo dnsmasq \
  --conf-file=/dev/null \
  --keep-in-foreground \
  --except-interface=lo0 \
  --interface="${DNSMASQ_IFACE}" \
  --bind-interfaces \
  --dhcp-range="${DNSMASQ_DHCP_RANGE}" \
  --dhcp-leasefile="${DNSMASQ_LEASEFILE}" \
  --local="/${DNSMASQ_DOMAIN}/" \
  --expand-hosts \
  --domain="${DNSMASQ_DOMAIN}" \
  --address="/${DNSMASQ_HOST_NAME}/${VBOX_HOST_IP}" \
  --log-queries \