def build_dhcp_response(self, msg_type, xid, client_mac, client_ip="0.0.0.0"): # Construct the packet header packet = bytearray()
def start(self): print(f"[*] TFTP Server listening on port TFTP_PORT...") while True: data, client_addr = self.socket.recvfrom(1024) # Handle TFTP in a new thread so DHCP isn't blocked threading.Thread(target=self.handle_tftp_request, args=(data, client_addr)).start()
# Verify ACK ack_opcode, ack_block = struct.unpack('!HH', ack_data[:4]) if ack_opcode == TFTP_OPCODES['ACK'] and ack_block == block_num: break except socket.timeout: print(f"[TFTP] Timeout on block block_num, retrying...") # Retry logic here... dhcp tftp
# 2. Server Identifier (Option 54) packet += bytes([54, 4]) + socket.inet_aton(TFTP_SERVER_IP)
# --- TFTP Constants --- TFTP_PORT = 69 TFTP_OPCODES = 'RRQ': 1, 'WRQ': 2, 'DATA': 3, 'ACK': 4, 'ERROR': 5 But together
1.4.7 Configuring DHCP and TFTP Services to Support PXE Clients
def handle_tftp_request(self, data, client_addr): opcode = struct.unpack('!H', data[:2])[0] # Server Hostname (64 bytes) + Boot File
On their own, DHCP hands out IP addresses, and TFTP transfers files. But together? They automate the entire process of booting a device from the network.
def send_file(self, filepath, client_addr): # Create a new socket for the data transfer (TFTP standard) # The server switches to a new random port for the transfer transfer_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) transfer_socket.bind((SERVER_IP, 0)) # Bind to random port transfer_socket.settimeout(5.0)
This combination is dangerous if exposed to the internet.
# Server Hostname (64 bytes) + Boot File (128 bytes) - leave empty for simplicity packet += b'\x00' * 192