Python Raw Socket to Ethernet Interface (Windows)
<p>I'm trying to create a DHCP Server and the first step is for me to send packets through my ethernet port. I'm trying to send packets to my Ethernet interface and having an error popping up.</p>

<p>The code is below.</p>

<pre><code>import socket

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.socket(socket.AF_PACKET, socket.SOCK_RAW)
  s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_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"))
</code></pre>

<p>I was having issues with the way the socket was being created. AF_PACKET is not recognized so I'm assuming that only works for Linux. I commented it out and added a new line below it. I ran it again and I started getting an error shown below.</p>

<pre><code>Traceback (most recent call last):
  File "eth.py", line 27, in &lt;module&gt;
    "hello"))
  File "eth.py", line 19, in sendeth
    s.bind((interface, 0))
  File "C:\Python27\lib\socket.py", line 224, in meth
    return getattr(self._sock,name)(*args)
socket.gaierror: [Errno 11001] getaddrinfo failed
</code></pre>

<p>Does anyone know why this is happening?</p>

<p>Looks like you don't get access to ethernet with this socket:</p>

<pre><code>s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_RAW)
</code></pre>

<p><code>socket.IPPROTO_RAW</code> gives you access to Level 3 protocol (IP), whereas ethernet is on Level 1 and 2. At level 3 an ethernet frame is already analyzed and its headers discarded. You need to get to Level 2 and <code>ETH_P_ALL</code> protocol seems to be a nice place to start. I don't believe python <code>socket</code> module implements it on that low level, but you can interact with WinAPI via <code>ctypes</code> module.</p>

python windows python-2.7 sockets dhcp