<p>Is it possible to determine the MAC address of the originator of a remote connection under Windows NT 4? The remote PC opens a socket connection into my application and I can get the IP address. However I need to determine the MAC address from the information available from the socket such as the IP address of the remote device.</p>

<p>I have tried using <code>SendARP</code> but this doesn't seem to be supported in Windows NT4.</p>

Try GetIpNetTable. This function is documented as supported as of NT 4.0 SP4.