exemplo_prof.py

import socket, sys
from socket import AF_PACKET, SOCK_RAW
from struct import *

def sendeth(eth_frame, interface = "eth0"):
	"""Send raw Ethernet packet on interface."""
	s = socket.socket(AF_PACKET, SOCK_RAW)
	s.bind((interface, 0))
	return s.send(eth_frame)

def checksum(msg):
	s = 0
	# loop taking 2 characters at a time
	for i in range(0, len(msg), 2):
		w = (ord(msg[i]) << 8) + (ord(msg[i+1]))
		s = s + w

	s = (s >> 16) + (s & 0xffff);
	s = ~s & 0xffff

	return s
 

if __name__ == "__main__":
	# src=fe:ed:fa:ce:be:ef, dst=52:54:00:12:35:02, type=0x0800 (IP)
	dst_mac = [0xff, 0xff, 0xff, 0xff, 0xff, 0xff]
	src_mac = [0x00, 0x0a, 0x11, 0x11, 0x22, 0x22]
	
	# Ethernet header
	eth_header = pack('!6B6BH', dst_mac[0], dst_mac[1], dst_mac[2], dst_mac[3], dst_mac[4], dst_mac[5], 
		src_mac[0], src_mac[1], src_mac[2], src_mac[3], src_mac[4], src_mac[5], 0x0800)
	
	source_ip = '192.168.1.101'
	dest_ip = '192.168.1.1'			# or socket.gethostbyname('www.google.com')
	 
	# ip header fields
	ihl = 5
	version = 4
	ihl_version = (version << 4) + ihl
	tos = 0
	tot_len = 20 + 20			# IP + TCP
	id = 54321  #Id of this packet
	frag_off = 0
	ttl = 255
	protocol = socket.IPPROTO_TCP
	check = 0
	saddr = socket.inet_aton(source_ip)
	daddr = socket.inet_aton(dest_ip)
	
	# the ! in the pack format string means network order
	ip_header = pack('!BBHHHBBH4s4s' , ihl_version, tos, tot_len, id, frag_off, ttl, protocol, check, saddr, daddr)
	check = checksum(ip_header)
	
	# build the final ip header (with checksum)
	ip_header = pack('!BBHHHBBH4s4s' , ihl_version, tos, tot_len, id, frag_off, ttl, protocol, check, saddr, daddr)
	 
	# tcp header fields
	source = 1234   # source port
	dest = 80   # destination port
	seq = 0
	ack_seq = 0
	doff = 5    #4 bit field, size of tcp header, 5 * 4 = 20 bytes
	#tcp flags
	fin = 0
	syn = 1
	rst = 0
	psh = 0
	ack = 0
	urg = 0
	window = socket.htons(5840)		# maximum allowed window size
	check = 0
	urg_ptr = 0
	 
	offset_res = (doff << 4) + 0
	tcp_flags = fin + (syn << 1) + (rst << 2) + (psh <<3) + (ack << 4) + (urg << 5)
	 
	# the ! in the pack format string means network order
	tcp_header = pack('!HHLLBBHHH' , source, dest, seq, ack_seq, offset_res, tcp_flags,  window, check, urg_ptr)
	 
	# pseudo header fields
	source_address = socket.inet_aton( source_ip )
	dest_address = socket.inet_aton(dest_ip)
	placeholder = 0
	protocol = socket.IPPROTO_TCP
	tcp_length = len(tcp_header)
	 
	psh = pack('!4s4sBBH' , source_address , dest_address , placeholder , protocol , tcp_length);
	psh = psh + tcp_header;
	 
	tcp_checksum = checksum(psh)
	 
	# make the tcp header again and fill the correct checksum
	tcp_header = pack('!HHLLBBHHH' , source, dest, seq, ack_seq, offset_res, tcp_flags,  window, tcp_checksum , urg_ptr)
	 
	# final full packet - syn packets dont have any data
	packet = eth_header + ip_header + tcp_header
	r = sendeth(packet, "enp1s0")
	
	print("Sent %d bytes" % r)