private int nonBlockRecv(byte[] recvBytes, int offset, int size, SocketFlags sf)
        {
            int bytesRecv = 0;

            while (true)
            {
                try
                {
                    nonBlockSend(new byte[1], 0, 0, sf);
                    bytesRecv = _socket.Receive(recvBytes, offset, size, sf);
                    break;
                }
                catch (SocketException excp)
                {
                    if (excp.ErrorCode != 10035) // WSAEWOULDBLOCK
                        throw excp;
                }
            }

            return bytesRecv;
        }

        private int nonBlockSend(byte[] sendBytes, int offset, int size, SocketFlags sf)
        {
            int bytesSent = 0;

            while (true)
            {
                try
                {
                    _socket.Send(sendBytes, offset, size, sf);
                    break;
                }
                catch (SocketException excp)
                {
                    if (excp.ErrorCode != 10035) // WSAEWOULDBLOCK
                        throw excp;
                }
            }

            return bytesSent;
        }

int recv = sock.Receive(data);
if (recv == 0)
{
    // Remote client has disconnected.
}
else
{
    // Remote client has sent data.
}

while (numberOfBytesRead == 0)
{
    try
    {
        IsConnected();
        _socket.ReceiveTimeout = 5000;
        numberOfBytesRead = _socket.Receive(myReadBuffer, 0, myReadBuffer.Length, SocketFlags.None);

    }
    catch (Exception e)
    {
        if (e.GetType() == typeof (LostConnection))
        {
            Status = SocketStatus.offline;
            throw;
        }
    }
}

public bool IsConnected(Socket s)
{
    try
    {
        ASCIIEncoding encoder = new ASCIIEncoding();
        byte[] buffer = encoder.GetBytes("test");
        s.Send(buffer, 0, buffer.Length, SocketFlags.None);
    }
    catch (Exception)
    {
        throw new LostConnection();
    }
    return s.Connected;
}