public TcpClient Connect(IPEndPoint host)
        {
            TcpClient client = new TcpClient();
            int maxTryCount = 5;
            while(true) {
                try
                {
                    client.Connect(host);
                    return client;
                }
                catch (SocketException) {
                    if(0 == --maxTryCount) {
                        throw;
                    }
                }
            }
        }