no_network_restart

#!/bin/bash
# 24.10.2019. - Restart if no network - gkelekovic 
## 

NIC=enp0s3              # most commonly is eth0
REGEX=10.0.             # network that DNCP servers serves in 192.168.0.0/16 or 10.0.0.0/16 - just first 2 numbers are needed
URL=google.com          # URL to ping
PING_COUNT=5            # ping count
CMD=`sudo /bin/ping -c $PING_COUNT $URL | grep -c "64 bytes"`   # command for counting sucessful pings 

logger "Started check if internet is avalible..."

check_ip() {
	logger "Checking network connection..."
	IP=`ifconfig $NIC | grep 'inet ' | cut -d: -f2 | awk '{ print $2}'`
	if [[ $IP =~ $REGEX ]];then
    		logger "IP from DHCP server found - $IP."
	else
    		logger "IP not found. Possbile problem with DHCP server."
	fi
}

restart_net() {
	logger "Restarting network and network manager..."
	/etc/init.d/networking restart >> /var/log/syslog
	/etc/init.d/network-manager restart >> /var/log/syslog
	logger "Network and network manager restarted."
}

reboot() {
	logger "Restarting server due no active Internet connection..."
	/sbin/shutdown -r now
}

## get current ip
IP=check_ip

## starting check
if (test "$CMD" -gt "3") then
	logger "Internet connection ok."
    	exit
else
    logger "$URL cannot be pinged. Trying again in 20 seconds"
    sleep 20
    if (test "$CMD" -gt "3") then
        logger "Internet connection ok."
	exit
    else
	logger "$URL still cannot be pinged."
	restart_net
	sleep 20
	    if (test "$CMD" -gt "3") then
		logger "Internet connection after network restart.."
        	exit
    	    else
		logger "$URL still cannot be pinged."
		reboot
		exit
	     fi
     fi
fi