import socket
import sys
import time
import struct
HOST, PORT = "10.60.66.66", 10086
def make_forward_iphdr(source_ip = '1.0.0.1', dest_ip = '2.0.0.2', proto = socket.IPPROTO_UDP) :
# ip header fields
ip_ihl = 5
ip_ver = 4
ip_tos = 0
ip_tot_len = 0 # kernel will fill the correct total length
ip_id = 54321 #Id of this packet
ip_frag_off = 0
ip_ttl = 255
ip_proto = proto
ip_check = 0 # kernel will fill the correct checksum
ip_saddr = socket.inet_aton ( source_ip ) #Spoof the source ip address if you want to
ip_daddr = socket.inet_aton ( dest_ip )
ip_ihl_ver = (ip_ver << 4) + ip_ihl
# the ! in the pack format string means network order
ip_header = struct.pack('!BBHHHBBH4s4s', ip_ihl_ver, ip_tos, ip_tot_len, ip_id, ip_frag_off, ip_ttl, ip_proto, ip_check, ip_saddr, ip_daddr)
return ip_header
def make_forward_udphdr(src_port = 1024, dst_port = 10086) :
udp_header = struct.pack('!HHHH', src_port, dst_port, 0, 0)
return udp_header
# checksum functions needed for calculation checksum
def checksum(msg):
s = 0
# loop taking 2 characters at a time
for i in range(0, len(msg), 2):
w = ord(msg[i]) + (ord(msg[i+1]) << 8 )
s = s + w
s = (s>>16) + (s & 0xffff);
s = s + (s >> 16);
#complement and mask to 4 byte short
s = ~s & 0xffff
return s
def make_tcp_data(ip_header, src_port = 1024, dst_port = 10086, source_ip='1.0.0.1', dest_ip='2.0.0.2', user_data = 'test') :
tcp_source = src_port # source port
tcp_dest = dst_port # destination port
tcp_seq = 454
tcp_ack_seq = 0
tcp_doff = 5 #4 bit field, size of tcp header, 5 * 4 = 20 bytes
#tcp flags
tcp_fin = 0
tcp_syn = 1
tcp_rst = 0
tcp_psh = 0
tcp_ack = 0
tcp_urg = 0
tcp_window = socket.htons (5840) # maximum allowed window size
tcp_check = 0
tcp_urg_ptr = 0
tcp_offset_res = (tcp_doff << 4) + 0
tcp_flags = tcp_fin + (tcp_syn << 1) + (tcp_rst << 2) + (tcp_psh <<3) + (tcp_ack << 4) + (tcp_urg << 5)
# the ! in the pack format string means network order
tcp_header = struct.pack('!HHLLBBHHH' , tcp_source, tcp_dest, tcp_seq, tcp_ack_seq, tcp_offset_res, tcp_flags, tcp_window, tcp_check, tcp_urg_ptr)
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) + len(user_data)
psh = struct.pack('!4s4sBBH' , source_address , dest_address , placeholder , protocol , tcp_length);
psh = psh + tcp_header + user_data;
tcp_check = checksum(psh)
#print tcp_checksum
# make the tcp header again and fill the correct checksum - remember checksum is NOT in network byte order
tcp_header = struct.pack('!HHLLBBH' , tcp_source, tcp_dest, tcp_seq, tcp_ack_seq, tcp_offset_res, tcp_flags, tcp_window) + struct.pack('H' , tcp_check) + struct.pack('!H' ,tcp_urg_ptr)
# final full packet - syn packets dont have any data
packet = ip_header + tcp_header + user_data
return packet
