quanergy_net_install.sh

#!/bin/bash
sudo apt-get install isc-dhcp-server -y
set interfaces
set addresses
set ip
# Find network interfaces
function find_interfaces()
{
    local ip_result=$(ip link | awk '{print $2}')
    ip_result=($ip_result)
    local counter=0
    while [ $counter -lt "${#ip_result[@]}" ]
    do
	interface="${ip_result[$counter]}"
	if [ "$interface" == "lo:" ]; then counter=$[$counter +2]; continue; fi
	interface=${interface::-1}
	interfaces+=($interface)
	counter=$[$counter +1]
	mac="${ip_result[$counter]}"
	addresses+=($mac)
	counter=$[$counter +1]
    done
}

# Find network interfaces
function display_interfaces()
{
    counter=0
    while [ $counter -lt "${#interfaces[@]}" ]
    do
	echo "To use ${interfaces[$counter]} enter $counter"
	counter=$[$counter +1]
    done
}

# Test an IP address for validity
function valid_ip()
{
    ip=$1
    local  stat=1

    if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
        OIFS=$IFS
        IFS='.'
        ip=($ip)
        IFS=$OIFS
        [[ ${ip[0]} -le 255 && ${ip[1]} -le 255 \
            && ${ip[2]} -le 255 && ${ip[3]} -le 252 && ${ip[3]} -ge 1 ]]
        stat=$?
    fi
    return $stat
}

set -e

echo "Looking for network interfaces..."
find_interfaces
if [ "${#interfaces[@]}" == "0" ]
then
    echo "No network interfaces found, please check your system"
    exit
fi

echo "Found ${#interfaces[@]} interfaces $interfaces"
echo "Choose the network interface to be used"
display_interfaces
iface=-1
while [[ "$iface" -ge "${#interfaces[@]}" || "$iface" -le "-1" ]]; do
    read -p "Ethernet interface " iface
done

ip_state="bad"
while [ "$ip_state" == "bad" ]; do
    read -p "IP address " subnet
    if valid_ip $subnet; then ip_state="good";  break; else echo "Please provide a valid IP address in [X.X.X.1 X.X.X.252]"; fi
done 

# Create /etc/network/interfaces
if [ -e /etc/network/interfaces ]
then
    sudo mv /etc/network/interfaces /etc/network/interfaces.bak
    sudo touch /etc/network/interfaces
fi

echo "# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

allow-hotplug ${interfaces[$iface]}
iface ${interfaces[$iface]} inet static
address $subnet
netmask 255.255.255.0
post-up service isc-dhcp-server restart" > /etc/network/interfaces
sudo chown root:root /etc/network/interfaces
sudo chmod 644 /etc/network/interfaces

if [ -e /etc/default/isc-dhcp-server ]
then
    sudo mv /etc/default/isc-dhcp-server /etc/default/isc-dhcp-server.bak
    sudo touch /etc/default/isc-dhcp-server
fi

echo "INTERFACES=\"${interfaces[$iface]}\"" > /etc/default/isc-dhcp-server
sudo chown root:root /etc/default/isc-dhcp-server
sudo chmod 644 /etc/default/isc-dhcp-server

# Create /etc/dhcp/dhcpd.conf
if [ -e /etc/dhcp/dhcpd.conf ]
then
    sudo mv /etc/dhcp/dhcpd.conf /etc/dhcp/dhcpd.conf.bak
    sudo touch /etc/dhcp/dhcpd.conf
fi

echo "#
# Simple configuration file for ISC dhcpd for Debian
#

ddns-update-style none;

option domain-name \"example.org\";
option domain-name-servers ns1.example.org, ns2.example.org;

log-facility local7;

subnet ${ip[0]}.${ip[1]}.${ip[2]}.0 netmask 255.255.255.0 {
  range ${ip[0]}.${ip[1]}.${ip[2]}.$[${ip[3]} +1] ${ip[0]}.${ip[1]}.${ip[2]}.254;
  option routers $subnet;
  default-lease-time 345600; 
  max-lease-time 31557600; 
}" > /etc/dhcp/dhcpd.conf
sudo chown root:root /etc/dhcp/dhcpd.conf
sudo chmod 644 /etc/dhcp/dhcpd.conf

# Make the chosen interface unmanaged
if [ -e /etc/NetworkManager/NetworkManager.conf ]
then
    sudo mv /etc/NetworkManager/NetworkManager.conf /etc/NetworkManager/NetworkManager.conf.bak
    sudo touch /etc/NetworkManager/NetworkManager.conf
fi
echo "[main]
plugins=ifupdown,keyfile,ofono
dns=dnsmasq

[ifupdown]
managed=false

[keyfile]
unmanaged-devices=mac:${addresses[$iface]}
" > /etc/NetworkManager/NetworkManager.conf
sudo chown root:root /etc/NetworkManager/NetworkManager.conf
sudo chmod 644 /etc/NetworkManager/NetworkManager.conf