I am trying to write an application which will take an incoming connection from a Remote Desktop client and perform a simple port redirection to another computer.  I have attached the code for a sample console application with a greatly simplified version of what I am trying to do.  This sample will listen on a local IP/port and forward any data to the remote RDP server.  The problem is, when I run this program and type in the computer's IP (192.168.1.139) and port 4242 into the RDC interface it connects and sends 4 sets of packets between the RDC and RDP server.  However, when it gets to the point where it asks for the credential which I put in and click OK the RDC client then displays "Configuring remote session" until it finally times out.

If I put in the IP address of the destination server (192.168.1.3 in this case) into the RDC and enter the same credentials it works fine.  Thus verifying that my credentials are fine and that my user has permissions on the remote computer to login via RD.

Please don't respond with suggestions of other products that I should use to accomplish this as I am trying to make a product of my own to do this that does not require 3rd party applications.

In my case the client(192.168.1.139) is Win7(x64) using VS2008 and RDP (102.168.1.3) is running Win2008R2(x64)

Anyone know what I need to do to this code to make it properly pass the data from client to server to enable the Remote Desktop session to complete connection and work properly?

Things I've tried:
    - Increasing buffer size
    - Increasing both sockets send/receive buffer size and disabling DontFragment
    - Using complete rework with Async socket interaction (ended with the same lockup in the same location)
    - Recreating the project in VS2010RC and copying the code (no change in results)
    - adding 1 second delays between all socket operations to rule out timing issues (no change in results)
    - Peeking at socket buffer data and only doing reads when there was data waiting (no change in results)
    - Tried putting both Receive calls into loops to continue trying to retrieve data even when they return 0 bytes
    - Tried only allocating one buffer and using it for all calls

using System;
using System.Net;
using System.Net.Sockets;

namespace PortForwardTest
{
    class Program
    {
        static void Main(string[] args)
        {
            int rdpPortNum = 3389;
            int redirPortNum = 4242;
            int BufferSize = 64 * 1024;
            try
            {
                Console.WriteLine("Starting up...");
                IPEndPoint redirEndpoint = new IPEndPoint(IPAddress.Parse("192.168.1.139"), redirPortNum); // Local Machine
                IPEndPoint RDPEndpoint = new IPEndPoint(IPAddress.Parse("192.168.1.3"), rdpPortNum); // Remote Machine

                Socket rdpSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                Socket redirListenSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

                Console.WriteLine("Listening for connection ...");
                redirListenSocket.Bind(redirEndpoint); 
                redirListenSocket.Listen(1); // Listen on local port

                Socket clientSocket = redirListenSocket.Accept();
                rdpSocket.Connect(RDPEndpoint); // Connect to remote computer on RDP port

                byte[] Buffer = null;
                int rdpSendSize = 0;
                int rdpReceiveSize = 0;
                int redirSendSize = 0;
                int redirReceiveSize = 0;

                while (true)
                {
                    Buffer = new byte[BufferSize];
                    redirReceiveSize = clientSocket.Receive(Buffer, BufferSize, SocketFlags.None);

                    Console.WriteLine("Received {0} bytes from redir port. Sennding to RDP port.", redirReceiveSize);
                    rdpSendSize = rdpSocket.Send(Buffer, redirReceiveSize, SocketFlags.None);
                    Console.WriteLine("Sent {0} bytes to RDP. Waiting for response...", rdpSendSize);

                    Buffer = null;
                    Buffer = new byte[BufferSize];
                    rdpReceiveSize = rdpSocket.Receive(Buffer, BufferSize, SocketFlags.None);

                    Console.WriteLine("Received {0} bytes from RDP. Sending to redir port", rdpReceiveSize);
                    redirSendSize = clientSocket.Send(Buffer, rdpReceiveSize, SocketFlags.None);
                    Console.WriteLine("Sent {0} bytes to redirPort.  Waiting for response...", redirSendSize);
                    Buffer = null;
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception: " + ex.Message);
            }
            Console.ReadKey();
        }
    }
}

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