internal bool IsSocketConnected()
    {
        if (!_socket.Connected)
        {
            return false;
        }

        if (_socket.Poll(1000, SelectMode.SelectRead) && _socket.Available == 0)
        {
            return false;
        }

        return true;
    }

SocketUtility socketUtility = SocketUtility.GetInstance();
Socket socket = socketUtility.GetSocket(); //the socket is still connected
try
{
//socketUtility.SocketKeepAlive();
// the socket disconnected
TcpClient tcpClient = new TcpClient { Client = socket };
NetworkStreamUtility networkStreamUtility = NetworkStreamUtility.GetInstance(tcpClient);
networkStreamUtility.TransferToServer(bytesToTransfer);
} catch (SocketException socketException)
{
//throw exception
}

Socket socket = new Socket(ipEndPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
socket.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.KeepAlive, true);

socket.NoDelay = true;