Concerning oneself with poster's identity (honestly, feels like a form of ad hominem) can't be exactly the solution.
It could be that relationship to the source matters - rather than author's identity. I mean, there is a subtle difference between "who wrote this?" and "do I trust this?". But the only implementation I can think of is some sort of web-of-trust and all attempts at implementing WoT I know about had utterly failed.
Either way, I believe some form of memetic immunity - not getting provoked - rather than attempts to identify and shut down "troll farms" and "fake news" - is an ultimate solution.
It could be that relationship to the source matters - rather than author's identity. I mean, there is a subtle difference between "who wrote this?" and "do I trust this?". But the only implementation I can think of is some sort of web-of-trust and all attempts at implementing WoT I know about had utterly failed.
Either way, I believe some form of memetic immunity - not getting provoked - rather than attempts to identify and shut down "troll farms" and "fake news" - is an ultimate solution.