C# Raw Sockets Port Forwarding

Question

I am trying to create a simple C# app which does port forwarding, and need to know how to use the IP_HDRINCL socket option to try to fake out the receiving end to think the connection is really to the source. Any examples would be greatly appreciated.

Answer 1

sock = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.IP );
sock.Bind( new IPEndPoint( IPAddress.Parse( "10.25.2.148" ), 0 ) );
sock.SetSocketOption( SocketOptionLevel.IP, SocketOptionName.HeaderIncluded, 1 );   
byte[] trueBytes = new byte[] { 1, 0, 0, 0 };
byte[] outBytes = new byte[] { 0, 0, 0, 0 };
sock.IOControl( IOControlCode.ReceiveAll, trueBytes, outBytes );
sock.BeginReceive( data, 0, data.Length, SocketFlags.None, new AsyncCallback( OnReceive ), null );

The only problem is that I've been able to successfully receive data from a raw socket like this, (including the IP header) but not send it.