Monitor Server Availability that doesn't run a webserver; ICMP Checks.

monitor-server-icmp.sh

#!/bin/bash
NOTIFYEMAIL=receivingemailaccount@domain.com
SENDEREMAIL=sendingemailaccount@domain.com
SERVER=fqdnoripaddress
PAUSE=300
FAILED=0
DEBUG=0

while true 
do
/usr/bin/ping -c 5 $SERVER > /dev/null 2>&1
CS=$?
# For debugging purposes
if [ $DEBUG -eq 1 ]
then
    echo "STATUS = $CS"
    echo "FAILED = $FAILED"
    if [ $CS -ne 0 ]
    then
        echo "$SERVER is down"

    elif [ $CS -eq 0 ]
    then
        echo "$SERVER is up"
    fi
fi

# If the server is down and no alert is sent - alert
if [ $CS -ne 0 ] && [ $FAILED -eq 0 ]
then
    FAILED=1
    if [ $DEBUG -eq 1 ]
    then
        echo "$SERVER failed"
    fi
    if [ $DEBUG = 0 ]
    then
        echo "$SERVER went down $(date)" | mutt -s "$SERVER went down" "$NOTIFYEMAIL" 
    fi

# If the server is back up and no alert is sent - alert
elif [ $CS -eq 0 ] && [ $FAILED -eq 1 ]
then
    FAILED=0
    if [ $DEBUG -eq 1 ]
    then
        echo "$SERVER is back up"
    fi
    if [ $DEBUG = 0 ]
    then
        echo "$SERVER is back up $(date)" | mutt -s "$SERVER is back up again" "$NOTIFYEMAIL"
    fi
fi
sleep $PAUSE
done

Place above script in /usr/local/bin

Place the following in a file (servercheck-name.service) at /etc/systemd/system
/-------------------------------------------/
[Unit]
After=network.target

[Service]
ExecStart=/usr/local/bin/monitor-website-systemdaemon.sh

[Install]
WantedBy=default.target
/-------------------------------------------/

After both files are placed:
systemctl enable servercheck-name.service
systemctl start servercheck-name.service
systemctl status servercheck-name.service