SetSocketKeepAliveIO.cs

private void SetKeepAliveIOControl(Socket socket, uint interval, uint retryInterval, bool enabled)
{
    int size = sizeof(UInt32);
    uint on = enabled ? (uint)1 : (uint)0;
    byte[] inArray = new byte[size * 3];
    Array.Copy(BitConverter.GetBytes(on), 0, inArray, 0, size);
    Array.Copy(BitConverter.GetBytes(interval), 0, inArray, size, size);
    Array.Copy(BitConverter.GetBytes(retryInterval), 0, inArray, size * 2, size);
    socket.IOControl(IOControlCode.KeepAliveValues, inArray, null);
}