Hilariously, LewRockwell.com's front page teaser for the reprint runs like this:
Open BordersTo which the reply is, "both, which is why libertarianism, like all liberalism, is suicidal."
Essential to libertarianism, or incompatible with it?
Open borders are essential to libertarianism because borders impede the human "right" to do whatever one wants — in this case, jump the border of another country and violates its laws — but then again are incompatible with libertarianism because the people jumping the border are not libertarians but big government liberals. And many of them are violent criminals, which kind of blows up libertarianism's famously ludicrous NAP — non-aggression principle.
Libertarian ideas about limited government are anathema to the "migrants" who are flooding Europe. They're headed there for the welfare. Mexicans crossing our border don't think much of them either. That's why they vote for Democratic Party statists.
Thus does Mr. Mosquito explain why open borders fail. In Europe, they have come to their logical end: complete chaos, and the likely wrecking of the nations to which the migrants migrate.