protected internal void Listen()
        {
            try
            {
                tcpListener = new TcpListener(IPAddress.Any, 8888);
                tcpListener.Start();
                Console.WriteLine("Server started. Waiting connections...");

                while (true)
                {
                    TcpClient tcpClient = tcpListener.AcceptTcpClient();

                    ChatClient chatClient = new ChatClient(tcpClient, this);
                    Thread clientThread = new Thread(new ThreadStart(chatClient.Process));
                    clientThread.Start();
                }
            }
            catch(Exception ex)
            {
                Console.WriteLine(ex.Message);
                Disconnect();
            }
        }
 protected internal void AddConnection(ChatClient chatClient)
 {
     clients.Add(chatClient);
 }