I disagree with the middle-way answer: it also doesn't require any thinking.

In any forum, you should separate the emotional content from the factual content and only respond to the latter. This is quite different from taking the middle way.

Though there are moderate trolls whose inflammatory postings contain useful factual content, I prefer forums where extreme trolling is dealt with harshly. Dissent is uncorrelated with rudeness (meaning that moderating extreme trolling won't drown out dissent) and no-one wants to spend their online time with the horribleness of uncontrolled trolling.