1 import socket
2 import sys
3 import time
4 import struct
5
6 HOST, PORT = "10.60.66.66", 10086
7
8 def make_forward_iphdr(source_ip = '1.0.0.1', dest_ip = '2.0.0.2', proto = socket.IPPROTO_UDP) :
9 # ip header fields
10 ip_ihl = 5
11 ip_ver = 4
12 ip_tos = 0
13 ip_tot_len = 0 # kernel will fill the correct total length
14 ip_id = 54321 #Id of this packet
15 ip_frag_off = 0
16 ip_ttl = 255
17 ip_proto = proto
18 ip_check = 0 # kernel will fill the correct checksum
19 ip_saddr = socket.inet_aton ( source_ip ) #Spoof the source ip address if you want to
20 ip_daddr = socket.inet_aton ( dest_ip )
21
22 ip_ihl_ver = (ip_ver << 4) + ip_ihl
23
24 # the ! in the pack format string means network order
25 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)
26 return ip_header
27
28 def make_forward_udphdr(src_port = 1024, dst_port = 10086) :
29 udp_header = struct.pack('!HHHH', src_port, dst_port, 0, 0)
30 return udp_header
31
32 # checksum functions needed for calculation checksum
33 def checksum(msg):
34 s = 0
35
36 # loop taking 2 characters at a time
37 for i in range(0, len(msg), 2):
38 w = ord(msg[i]) + (ord(msg[i+1]) << 8 )
39 s = s + w
40
41 s = (s>>16) + (s & 0xffff);
42 s = s + (s >> 16);
43
44 #complement and mask to 4 byte short
45 s = ~s & 0xffff
46
47 return s
48
49 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') :
50 tcp_source = src_port # source port
51 tcp_dest = dst_port # destination port
52 tcp_seq = 454
53 tcp_ack_seq = 0
54 tcp_doff = 5 #4 bit field, size of tcp header, 5 * 4 = 20 bytes
55 #tcp flags
56 tcp_fin = 0
57 tcp_syn = 1
58 tcp_rst = 0
59 tcp_psh = 0
60 tcp_ack = 0
61 tcp_urg = 0
62 tcp_window = socket.htons (5840) # maximum allowed window size
63 tcp_check = 0
64 tcp_urg_ptr = 0
65
66 tcp_offset_res = (tcp_doff << 4) + 0
67 tcp_flags = tcp_fin + (tcp_syn << 1) + (tcp_rst << 2) + (tcp_psh <<3) + (tcp_ack << 4) + (tcp_urg << 5)
68
69 # the ! in the pack format string means network order
70 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)
71
72 source_address = socket.inet_aton(source_ip)
73 dest_address = socket.inet_aton(dest_ip)
74 placeholder = 0
75 protocol = socket.IPPROTO_TCP
76 tcp_length = len(tcp_header) + len(user_data)
77
78 psh = struct.pack('!4s4sBBH' , source_address , dest_address , placeholder , protocol , tcp_length);
79 psh = psh + tcp_header + user_data;
80
81 tcp_check = checksum(psh)
82 #print tcp_checksum
83
84 # make the tcp header again and fill the correct checksum - remember checksum is NOT in network byte order
85 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)
86
87 # final full packet - syn packets dont have any data
88 packet = ip_header + tcp_header + user_data
89 return packet
