Your own server

using System;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Threading;

class TcpDemo
{
    static void Main()
    {
        new Thread(Server).Start(); // Run server method concurrently. 
        Thread.Sleep (500);  // Give server time to start. 
        Client();
    }

    static void Client()
    {
        using (TcpClient client = new TcpClient("localhost", 99))
        using (NetworkStream n = client.GetStream())
        {
            BinaryWriter w = new BinaryWriter(n);
            w.Write("Hello");
            w.Flush();
            Console.WriteLine(new BinaryReader(n).ReadString());
        }
    }

    static void Server()  // Handles a single client request, then exits.
    {
        TcpListener listener = new TcpListener(IPAddress.Any, 99);
        listener.Start();
        using (TcpClient c = listener.AcceptTcpClient())
        using (NetworkStream n = c.GetStream())
        {
            string msg = new BinaryReader(n).ReadString(); 
            BinaryWriter w = new BinaryWriter(n);
            w.Write(msg + " right back!");
            w.Flush();  
        }
        listener.Stop();
    }
}