#!/bin/ash

# ###################
# Network host check
# ###################

# Checks the arp and dhcp cache every 10 minutes and sends the
# result over MQTT
# You need to have mosquitto_pub installed locally

# replace this with your localdomain - it will then be stripped 
# from the MQTT publishs

LOCALDOMAIN=.mydomain.local

# ###################
# arp cache scan
# ###################

do_arp_cache () {

for SCANNED_HOST in $(cat /proc/1/net/arp | /usr/bin/awk -F " "  '{ print "SCANHOSTIP=" $1  ";SCANHOSTMAC="  $4 ";SCANHOSTSTATUS="  $3 ";SCANHOSTNETWORK="  $6  }')
do
	eval $SCANNED_HOST
	#echo "Host: $SCANHOSTIP / $SCANHOSTMAC"
	if [ "$SCANHOSTNETWORK" != "HW" ] ; then 
		SCANHOSTNAME=$(/usr/bin/nslookup $SCANHOSTIP | /bin/grep name | /usr/bin/awk -F " = " '{print $2}' | /bin/sed -e s/$LOCALDOMAIN//)
		#echo $SCANHOSTNAME
		/usr/bin/mosquitto_pub -h localhost -t network -m "{\"interface\":\"$SCANHOSTNETWORK\",\"ip\":\"$SCANHOSTIP\",\"mac\":\"$SCANHOSTMAC\",\"hostname\":\"$SCANHOSTNAME\",\"status\":\"$SCANHOSTSTATUS\",\"source\":\"arp-cache\"}"
	fi
done
}

# ###################
# arp  scan
# ###################

do_arp_scan () {

for SCANNED_NETWORK in $(/sbin/route |/bin/grep "U " | /usr/bin/awk -F " "  '{ print "SCANINTERFACE=" $8  ";SCANNETMASK="  $1 "/24" }') 
do
	#echo "$SCANNED_NETWORK"
	eval $SCANNED_NETWORK
	for SCANNED_HOST in $(/usr/bin/arp-scan -qxI $SCANINTERFACE $SCANNETMASK | /usr/bin/awk -F " "  '{ print "SCANHOSTIP=" $1  ";SCANHOSTMAC="  $2 }' )
	do
		eval $SCANNED_HOST
		#echo "Host: $SCANHOSTIP / $SCANHOSTMAC"
		SCANHOSTNAME=$(/usr/bin/nslookup $SCANHOSTIP | /bin/grep name | /usr/bin/awk -F " = " '{print $2}' | /bin/sed -e s/$LOCALDOMAIN//)
		#echo $SCANHOSTNAME
		/usr/bin/mosquitto_pub -h localhost -t network -m "{\"interface\":\"$SCANINTERFACE\",\"ip\":\"$SCANHOSTIP\",\"mac\":\"$SCANHOSTMAC\",\"hostname\":\"$SCANHOSTNAME\",\"source\":\"arp-scan\"}"
	done
done
}


# ###################
# dhcp cache  scan
# ###################

do_dhcp_scan () {

for SCANNED_HOST in $(cat /tmp/dhcp.leases | /usr/bin/awk -F " "  '{ print "SCANHOSTIP=" $3  ";SCANHOSTMAC="  $2 ";SCANHOSTNAME="  $4  }' | /bin/sed s/*// )
do
	eval $SCANNED_HOST
	#echo "Host: $SCANHOSTIP / $SCANHOSTMAC"
	/usr/bin/mosquitto_pub -h localhost -t network -m "{\"ip\":\"$SCANHOSTIP\",\"mac\":\"$SCANHOSTMAC\",\"hostname\":\"$SCANHOSTNAME\",\"source\":\"dhcp-cache\"}"
done
}

# ###################
# main routine
# ###################


while (true) do
	do_arp_scan
	do_dhcp_scan
	do_arp_cache
	sleep 600
done