this is my dhcp server:
import socket
from scapy.all import *
from scapy.layers.dhcp import BOOTP, DHCP
from scapy.layers.inet import UDP, IP
from scapy.layers.l2 import Ether
def dhcp_server():
# Server parameters
server_ips = ['127.0.0.1']
server_port = 67
# Create a UDP socket for DHCP communication
dhcp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
dhcp_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
dhcp_socket.bind(('127.0.0.1', server_port))
print(f"DHCP server listening on port {server_port}")
# Loop to handle incoming DHCP requests
while True:
# Receive a DHCP request from a client
dhcp_request, client_address = dhcp_socket.recvfrom(1024)
print(f"Received DHCP request from {client_address[0]}:{client_address[1]}")
# Parse the DHCP request packet
dhcp_packet = DHCP(dhcp_request)
dhcp_options = dhcp_packet[DHCP].options
if not dhcp_options:
print(f"Invalid DHCP request from {client_address[0]}:{client_address[1]}")
continue
dhcp_message_type = [opt[1] for opt in dhcp_options if opt[0] == 'message-type'][0]
client_mac_address = dhcp_packet[Ether].src
# Assign an IP address to the client
if dhcp_message_type == 1: # DHCP Discover
# Create a DHCP offer packet
dhcp_offer = Ether(src=get_if_hwaddr('eth0'), dst=client_mac_address) / IP(src=server_ips[0],
dst='255.255.255.255') / UDP(
sport=67, dport=68) / BOOTP(op=2, yiaddr='0.0.0.0', siaddr=server_ips[0],
chaddr=client_mac_address) / DHCP(
options=[('message-type', 'offer'), ('subnet_mask', '255.255.255.0'), ('domain_name_server', '8.8.8.8'),
('router', server_ips[0]), ('lease_time', 120)])
# Send the DHCP offer packet to the client
sendp(dhcp_offer, iface='eth0', verbose=0)
print(f"Sent DHCP offer to {client_address[0]}:{client_address[1]}")
elif dhcp_message_type == 3: # DHCP Request
# Create a DHCP acknowledgement packet
dhcp_ack = Ether(src=get_if_hwaddr('eth0'), dst=client_mac_address) / IP(src=server_ips[0],
dst='255.255.255.255') / UDP(
sport=67, dport=68) / BOOTP(op=2, yiaddr=dhcp_packet[BOOTP].yiaddr, siaddr=server_ips[0],
chaddr=client_mac_address) / DHCP(
options=[('message-type', 'ack'), ('subnet_mask', '255.255.255.0'), ('domain_name_server', '8.8.8.8'),
('router', server_ips[0]), ('lease_time', 120)])
# Send the DHCP acknowledgement packet to the client
sendp(dhcp_ack, iface='eth0', verbose=0)
print(f"Sent DHCP acknowledgement to {client_address[0]}:{client_address[1]}")
if __name__ == "__main__":
dhcp_server()
my dhcp server listens to incomming requests and respond to them accordingly.
this is my client:
import socket
import struct
# Client parameters
server_ip = '127.0.0.1'
server_port = 67
# Create a UDP socket for DHCP communication
dhcp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
dhcp_socket.bind(('0.0.0.0', 68)) # Use port 68 for DHCP client
# Construct the DHCP request message
# See https://datatracker.ietf.org/doc/html/rfc2131#section-2
# for the format of a DHCP request message
transaction_id = b'\x39\x03\xF3\x26' # 4-byte transaction ID
flags = b'\x00\x01' # Broadcast flag (bit 15) set to 1
client_hw_address = b'\x08\x00\x27\x01\x9C\xEA' # Example MAC address
client_ip_address = b'\x00\x00\x00\x00' # Requesting a new IP address
server_ip_address = b'\x00\x00\x00\x00' # Server IP address is initially 0
relay_agent_ip_address = b'\x00\x00\x00\x00' # No relay agent in this case
client_mac_padding = b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
dhcp_options = b'\x63\x82\x53\x63' # Magic cookie + DHCP options
dhcp_options += b'\x35\x01\x01' # DHCP Message Type option: DHCPREQUEST
dhcp_options += b'\x32\x04\xc0\xa8\x01\x64' # Requested IP address option
dhcp_options += b'\x0f\x06\x00\x00\x3c\x50\x4b\x05\xdc' # Hostname option
dhcp_options += b'\x0c\x0c\x70\x79\x74\x68\x6f\x6e\x2d\x62\x6f\x6f\x74' # Hostname option
dhcp_options += b'\x37\x04\x01\x03\x06\x2c' # Parameter Request List option
dhcp_request = b'\x01' # Message Type: DHCPDISCOVER
dhcp_request += client_mac_padding + client_hw_address
dhcp_request += client_mac_padding + client_ip_address
dhcp_request += server_ip_address + relay_agent_ip_address
dhcp_request += transaction_id + client_mac_padding
dhcp_request += dhcp_options + b'\xff' # End of DHCP options
# Send the DHCP request to the DHCP server
dhcp_socket.sendto(dhcp_request, (server_ip, server_port))
print(f"Sent DHCP request to {server_ip}:{server_port}")
# Wait for the DHCP response from the server
dhcp_response, server_address = dhcp_socket.recvfrom(1024)
print(f"Received DHCP response '{dhcp_response.hex()}' from {server_address[0]}:{server_address[1]}")
if len(dhcp_response) < 240:
print('Error: Malformed DHCP response')
else:
dhcp_header = struct.unpack('!B B B B 4s 2s 2s 4s 4s 4s 4s 6s', dhcp_response[:28])
dhcp_options = dhcp_response[240:]
dhcp_message_type = dhcp_options[2]
if dhcp_message_type == 0x02: # DHCP offer
offered_ip_address = socket.inet_ntoa(dhcp_options[16:20])
print(f"DHCP server offered IP address {offered_ip_address}")
dhcp_xid = dhcp_header[3]
# Construct the DHCP request packet
dhcp_request = struct.pack('!B B B B 4s 2s 2s 4s 4s 4s 4s 6s', 0x01, 0x01, 0x06, 0x00,
dhcp_header[4], dhcp_header[5], dhcp_header[6], b'\x00\x00\x00\x00',
dhcp_header[8], b'\x00\x00\x00\x00', dhcp_header[10], dhcp_header[11])
dhcp_request += struct.pack('!B B B B', 0x35, 0x01, 0x03, 0x0f) # DHCP message type: Request
dhcp_request += struct.pack('!B B B B', 0x32, 0x04, 0x00, 0x00, 0x1c) # DHCP requested IP address
dhcp_request += struct.pack('!B B B B', 0x37, 0x03, 0x03, 0x01, 0x06) # DHCP parameter request list
dhcp_request += struct.pack('!B B B B', 0xff, 0x00, 0x00, 0x00) # End of options
# Send the DHCP request packet to the server
dhcp_socket.sendto(dhcp_request, (server_ip, server_port))
print(f"Sent DHCP request for IP address {offered_ip_address}")
# Wait for the DHCP response to the request
dhcp_response, server_address = dhcp_socket.recvfrom(1024)
print(f"Received DHCP response '{dhcp_response.hex()}' from {server_address[0]}:{server_address[1]}")
if len(dhcp_response) < 240:
print('Error: Malformed DHCP response')
else:
dhcp_header = struct.unpack('!B B B B 4s 2s 2s 4s 4s 4s 4s 6s', dhcp_response[:28])
dhcp_options = dhcp_response[240:]
dhcp_message_type = dhcp_options[2]
if dhcp_message_type == 0x05: # DHCP ack
assigned_ip_address = socket.inet_ntoa(dhcp_options[16:20])
print(f"DHCP server assigned IP address {assigned_ip_address}")
my client send a ping to google.com and wait for a respond from the server using the localhost ip and it is not working, i get a message that the dhcp discover sent and that's it, no respond.
now there is a problem that the server is listening to the incomming request but when i activate my client it does not resond to the packet, is there anything i could fix in my code for it to work properly, i have tried several client and ways to improve it but yet it is not working,
the problem is solved, no need to answer anymore.