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# For establishing the packet structure (Used later on), this will allow direct access to the methods and functions in the struct module
from struct import pack
# For encoding
import base64 # base64 module
import binascii # binascii module
# Create a raw socket.
try:
s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_RAW)
except socket.error as msg:
print(msg)
sys.exit()
# 0 or IPPROTO_TCP for STREAM and 0 or IPPROTO_UDP for DGRAM. (man ip7). For SOCK_RAW you may specify a valid IANA IP protocol defined in RFC 1700 assigned numbers.
# IPPROTO_IP creates a socket that sends/receives raw data for IPv4-based protocols (TCP, UDP, etc). It will handle the IP headers for you, but you are responsible for processing/creating additional protocol data inside the IP payload.
# IPPROTO_RAW creates a socket that sends/receives raw data for any kind of protocol. It will not handle any headers for you, you are responsible for processing/creating all payload data, including IP and additional headers. (link)
packet = ''
src_ip = "127.0.0.1"
dst_ip = "127.0.0.1"
##################
##Build Packet Header##
##################
# Lets add the IPv4 header information
# This is normally 0x45 or 69 for Version and Internet Header Length
ip_ver_ihl =
# This combines the DSCP and ECN fields. Type of service/QoS
ip_tos =
# The kernel will fill in the actually length of the packet
ip_len = 0
# This sets the IP Identification for the packet. 1-65535
ip_id =
# This sets the RES/DF/MF flags and fragmentation offset
ip_frag =
# This determines the TTL of the packet when leaving the machine. 1-255
ip_ttl =
# This sets the IP protocol to 16 (CHAOS) (reference IANA) Any other protocol it will expect additional headers to be created.
ip_proto =
# The kernel will fill in the checksum for the packet
ip_check = 0
# inet_aton(string) will convert an IP address to a 32 bit binary number
ip_srcadd = socket.inet_aton(src_ip)
ip_dstadd = socket.inet_aton(dst_ip)
#################
## Pack the IP Header ##
#################
# This portion creates the header by packing the above variables into a structure. The ! in the string means 'Big-Endian' network order, while the code following specifies how to store the info. Endian explained. Refer to link for character meaning.
# Your custom protocol fields or data. We are going to just insert data here. Add your message where the "?" is. Ensure you obfuscate it though...don't want any clear text messages being spotted! You can encode with various data encodings. Base64, binascii
message = b'last_name' #This should be the student's last name per the prompt
hidden_msg = binascii.hexlify(message) #Students can choose which encodeing they want to use.
# final packet creation
packet = ip_header + hidden_msg
# Send the packet. Sendto is used when we do not already have a socket connection. Sendall or send if we do.
s.sendto(packet, (dst_ip, 0))
# socket.send is a low-level method and basically just the C/syscall method send(3) / send(2). It can send less bytes than you requested, but returns the number of bytes sent.
# socket.sendall is a high-level Python-only method that sends the entire buffer you pass or throws an exception. It does that by calling socket.send until everything has been sent or an error occurs.
