One way of sending raw Ethernet packets in Python

sendeth.py

"""Demonstrates how to construct and send raw Ethernet packets on the
network.

You probably need root privs to be able to bind to the network interface,
e.g.:

    $ sudo python sendeth.py
"""

from socket import *

def sendeth(src, dst, eth_type, payload, interface = "eth0"):
  """Send raw Ethernet packet on interface."""

  assert(len(src) == len(dst) == 6) # 48-bit ethernet addresses
  assert(len(eth_type) == 2) # 16-bit ethernet type

  s = socket(AF_PACKET, SOCK_RAW)

  # From the docs: "For raw packet
  # sockets the address is a tuple (ifname, proto [,pkttype [,hatype]])"
  s.bind((interface, 0))
  return s.send(src + dst + eth_type + payload)

if __name__ == "__main__":
  print("Sent %d-byte Ethernet packet on eth0" %
    sendeth("\xFE\xED\xFA\xCE\xBE\xEF",
            "\xFE\xED\xFA\xCE\xBE\xEF",
            "\x7A\x05",
            "hello"))

@cslarsen Could I use this to talk to the internet from an air gapped computer via QR code? I have the QR two way comm figured out...

Using code based on this I encountered this problem - when viewed in Wireshark, it seems Python is tacking some extra bytes onto the end of this "raw" data. Anyone else experiencing this?

@geajack If you send less than Ethernet's minimum frame size it will be padded. The number is (as I remember) 60 bytes. It is actually a good sign if your packet is padded.