Parse ICMP packet with sockets

parse_icmp_sockets.py

import socket
import struct

# create a raw socket that listens for ICMP packets
icmp = socket.getprotobyname('icmp')
sock = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)

while True:
    packet, address = sock.recvfrom(1024)
    print(len(packet))
    # parse the IP header to determine the protocol
    ip_header = packet[:20]
    iph = struct.unpack('!BBHHHBBH4s4s', ip_header)
    version = iph[0] >> 4 # Shifts bit similar to slicing, it means get first 4 bits 
    ihl = iph[0] & 0xF # This means get last 4 bits from iph[0] octet

    protocol = iph[6]

    if protocol == socket.IPPROTO_ICMP:
        # unpack the ICMP header fields
        icmp_header = packet[20:28]
        icmp_type, code, checksum, packet_id, sequence = struct.unpack('!BBHHH', icmp_header)

        # print the ICMP packet information
        print(f'Received ICMP packet from {address}:')
        print(f'  Type: {icmp_type}')
        print(f'  Code: {code}')
        print(f'  Checksum: {checksum}')
        print(f'  Packet ID: {packet_id}')
        print(f'  Sequence: {sequence}')
        print()


    # unpack the ICMP header fields
    icmp_type, code, checksum, packet_id, sequence = struct.unpack('!BBHHH', packet[20:28])

    # print the ICMP packet information
    print(f'Received ICMP packet from {address}:')
    print(f'  Type: {icmp_type}')
    print(f'  Code: {code}')
    print(f'  Checksum: {checksum}')
    print(f'  Packet ID: {packet_id}')
    print(f'  Sequence: {sequence}')