Peer-to-Peer (P2P) protocols are susceptible to Localized Eclipse Attacks (LEA), i.e., attacks where a victim peer's environment is masked by malicious peers which are then able to instigate progressively insidious security attacks. To obtain effective placement of malicious peers, LEAs significantly benefit from overlay topology-awareness. Hence, we propose heuristics for Chord, Pastry and Kademlia to assess the protocols' LEA susceptibility based on their topology characteristics and overlay routing mechanisms. As a result, our method can be used for P2P protocol parameter tuning in order to substantially mitigate LEAs. We present evaluations highlighting LEA's impact on contemporary P2P protocols. Our proposed heuristics are abstract in nature, making them applicable plus customizable for many other structured P2P protocols. We validate our model's accuracy through a simulation case study. © 2012 IEEE.