This simple program tunnels UDP DNS packets to a TCP port

DnsTunnel.cs

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

namespace DnsTunnel
{
    class Program
    {
        static void OpenTunnel(int listenerPort, string targetHost, int targetPort)
        {
            try
            {
                // Create a UdpClient for listening
                UdpClient UDPServer = new UdpClient(listenerPort);

                // Create a TcpClient to forward messages to the the team server
                TcpClient forwarder = new TcpClient(targetHost, targetPort);
                NetworkStream stream = forwarder.GetStream();

                while (true)
                {
                    IPEndPoint source = new IPEndPoint(IPAddress.Any, 0);
                    // Block until a message is received
                    Byte[] data = UDPServer.Receive(ref source);

                    // Send data to the team server
                    stream.Write(data, 0, data.Length);

                    // Read the response
                    byte[] response = new byte[16384];
                    int numBytesRead = stream.Read(response, 0, response.Length);

                    // Send the response
                    UDPServer.Send(response, numBytesRead, source);
                }
            }
            catch (Exception e)
            {
                Console.Error.WriteLine(e.ToString());
            }
        }

        static void Main(string[] args)
        {
            int UDPPort;
            int TCPPort;

            if (args.Length != 3 || !(int.TryParse(args[0], out UDPPort) && int.TryParse(args[2], out TCPPort)))
            {
                Console.Error.WriteLine("Syntax Error. Please provide the following positional arguments:\n[Local UDP Port] [Remote TCP Host] [Remote TCP Port]\nExample: 53 127.0.0.1 53530");
                return;
            }

            OpenTunnel(UDPPort, args[1], TCPPort);
        }
    }
}