from scapy.all import sniff
IP_MAC_Map = {}

def processPacket(packet):
	src_IP = packet['ARP'].psrc
	src_MAC = packet['Ether'].src
	if src_MAC in IP_MAC_Map.keys():
		if IP_MAC_Map[src_MAC] != src_IP :
			try:
				old_IP = IP_MAC_Map[src_MAC]
			except:
				old_IP = "unknown"
			message = ("\n Possible ARP attack detected \n "
			+ " It is possible that the machine with IP address 	 \n " + str(src_IP) + " is pretending to be " 
			+ str(old_IP) + "\n ")
			return message
	else:
		IP_MAC_Map[src_MAC] = src_IP
	
sniff(count=0, filter="arp", store = 0, prn = processPacket)