While online trolling is mostly committed by a small number of trolls who enjoy irritating other members in the same social space, it is also often observed that a larger number of trolls establish an online community dedicated to trolling against the public outside. Using network data from two Korean online communities, we fit a longitudinal fixed effects model to test the trolling community's network structures differ from an ordinary online community. We found that the trolling community, ILBE, had a unique reward mechanism to maintain the anonymity of trolls in order to make the illegitimate behaviors collectively sustainable.