For the extreme libertarian, ethics are simple. Here’s an excerpt from The Philosophy of Liberty, by Ken Schoolland:
“A product of your life and liberty is your property. Property is the fruit of your labor, the product of your time, energy, and talents. It is that part of nature that you turn to valuable use. And it is the property of others that is given to you by voluntary exchange and mutual consent.”
But in the real world, we immediately run into complications. Schoolland seems to be following Murray Rothbard’s Ethics of Liberty.
The most important complication is that the product of your time, energy and talents doesn't depend on those inputs alone. It also depends on the society in which you function, the public goods allocated to you by law and custom, and the share of nature likewise assigned you as a private good by the society in which you live.
For example, as an individual adult US citizen of median time, energy and talents you might expect an annual individual income of something above $28,000. Cast away on Robinson Crusoe's desert island, the same time, energy and talents might earn you the equivalent of $500 a year in goats and cocoanuts.
Which is why the number of people that want to live in the United States is much greater than the number the current citizens allow.