Ethernet CRC32 calculation - software vs algorithmic result

Question

I\'m trying to calculate the Frame Check Sequence (FCS) of an Ethernet packet byte by byte. The polynomial is 0x104C11DB7. I did follow the XOR-SHIFT algorithm

Answer 1

This snippet writes the correct CRC for Ethernet.

Python 3

# write payload
for byte in data:
    f.write(f'{byte:02X}\n')
# write FCS
crc = zlib.crc32(data) & 0xFFFF_FFFF
for i in range(4):
    byte = (crc >> (8*i)) & 0xFF
    f.write(f'{byte:02X}\n')

Python 2

# write payload
for byte in data:
    f.write('%02X\n' % ord(byte))
# write FCS
crc = zlib.crc32(data) & 0xFFFFFFFF
for i in range(4):
    byte = (crc >> (8*i)) & 0xFF
    f.write('%02X\n' % byte)

Would have saved me some time if I found this here.