I thought you were going to link them to the brownshirts. Certainly they seem similar in many regards. I can't think of anything good to say about someone who thinks vigilante violence is a noble act.

Are you claiming they're descended from the Reichsbanner? Do you have a source for that?

No, I mean the label Antifaschistische Aktion and its abbreviation Antifa literally originated with labor groups opposing the rise of Hitler and the Nazi Party.

I'm not a historian, but understanding is that there isn't real continuity between that antifa (labor and communist anti-Nazi groups) and the modern antifa (the punk-direct-action-aesthetic antifa), which came about much later in the century, but that the name and association was adopted intentionally.