A watchdog script to monitor the network connectivity (ping status) and reboot when there is no connection

watchdog-network.sh

# A watchdog script to monitor the ping status and reboot the device 
#  when there is no connection after a specified number of tries.

#!/bin/sh

echo '\nStarted watchdog script.'

address=8.8.8.8 # or a local gateway address
max=5 # number of retries before reboot
interval=120 # seconds between each retry
verbose=false # set to true to print also the success logs

counter=0
while true; do
	now=$(date --rfc-3339=seconds)

	# check connection to address
	# -q quiet
	# -c nb of pings to perform
	ping -q -c1 ${address} > /dev/null
	if [ $? -ne 0 ]
	then
		counter=$((counter+1))
		printf '%s -- %s -- Failed to ping %d\n' "$now" $address $counter
	else
		counter=0
		$verbose && printf '%s -- %s -- OK\n' "$now" $address
	fi

	# if $max consecutive pings fail
	if [ "$counter" -eq "$max" ]
	then
		# reboot the device
		echo "Rebooting..."
		reboot
	fi

	sleep $interval
done

## To start after reboot, e.g. using Crontab (make sure the logs are rotated):
# sudo crontab -e
## Add:
# @reboot sh /home/pi/watchdog-network.sh >> /var/log/watchdog-network.log 2>&1