The natural rights can be easily defined as the rights any human would enjoy when not submitted to (physical) violent coercion. That is, the rights one would enjoy if living on a desert island. Among these rights we find the right to property. I claim that something belongs to me which didn’t belong to anyone (therefore without physical violence), I obtain something from a transaction that doesn’t imply physical violence, I create something by my activity without initiating physical violence on others and so on and so forth. That makes me own things. And this is a natural right as someone (be them private or public -the State- robbers) needs to either do physical violence or credibly threaten physical violence, to remove it to me against my will.
So property is something that physical violence serves only to defend. If you need physical violence to obtain something, then this something was someone else’s property. Now “intellectual property” is therefore not property, as anyone can obtain it without exerting violence against its “owner” and the only violence taking place is the one INITIATED by the supposed “owner” or the State in his/her name. Namely, that initiation of violence would actually locate the real rights on the side of the “copier”, “pirate”, “copyright infringer” or whatever and make both the State and the claimant the thieves.
This is really not news when it comes to the State, as this entity was defined (and that’s the prevalent definition, to this day at least) by Max Webber as being the organisation “that successfully claims the monopoly of the legitimate use of physical force within a given territory”. The “legitimate” being totally arbitrary since when you have the monopoly of the use of physical force/violence, you also are the one who defines what is legitimate. But really, keep it in mind, every time you claim for you (or for others) some kind of “intellectual property”, you are de facto initiating violence against people that have not attacked you in any real way, only threatened a monopoly you would have liked to see somewhere. And imposed monopolies are bad, always (which is why the State is bad, intellectual property is bad, etc.) Not only from a moral standpoint but also from an economic/welfare standpoint.