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rogue dhcp detector
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#!/usr/bin/python | |
import sys | |
from os import geteuid | |
from scapy.all import * | |
#check for root | |
if geteuid() != 0: | |
print "This must be run as root" | |
exit(1) | |
# CONFIGURATION # | |
""" | |
Scapy normally makes sure that replies come from the same IP address the stimulus was sent to. But our DHCP packet is sent to the broadcast address (255.255.255.255) and any answer packet will have the IP address of the replying DHCP server as its source IP address (e.g. 192.168.1.1). Because these IP addresses don't match, we have to disable Scapy's check with conf.checkIPaddr = False before sending the stimulus. | |
""" | |
conf.checkIPaddr = False | |
fam,hw = get_if_raw_hwaddr(conf.iface) | |
# CRAFTING THE DHCP PACKET # | |
dhcp_discover_packets = Ether(dst="ff:ff:ff:ff:ff:ff")/IP(src="0.0.0.0",dst="255.255.255.255")/UDP(sport=68,dport=67)/BOOTP(chaddr=hw)/DHCP(options=[("message-type","discover"),"end"]) | |
# SENDING THE PACKET # | |
ans, unans = srp(dhcp_discover_packets, multi=True, timeout=3) | |
# GET THE RESULTS # | |
replyingServers=[] | |
for result in ans: | |
print "\nGot a DHCP offer from", result[1][IP].src, "with MAC address", result[1][Ether].src | |
replyingServers.append(result[1][IP].src) | |
if len(replyingServers) > 1: | |
print ("!!!!!!!!!!!!\nWARNING: MORE THAN 1 DHCP SERVER REPLIED TO OUR PACKETS\n!!!!!!!!!!!!") | |
elif len(replyingServers) < 1: | |
print ("Didnt get a reply from anyone....is there a DHCP server on this subnet?") | |
else: | |
print ("\nGot one DHCP reply, looks good!") |
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You have to choose between python2 and 3. So for print it is either the function print() or the statement print without (). Do not mix the two.