AbstractDue to its distributed nature, the P2P networks are subject to more intricate attacks than client-server networks. Therefore, the security issues on a P2P network represent a great research challenge. Most P2P networks do not have a central management, and causes them can be endangered by its own nodes if enough of them decide to behave maliciously. In this paper, we evaluate the performance of P2P networks against an Eclipse attacks. Specifically, we evaluate the performance of the unstructured P2P networks and super-peer P2P systems against the Eclipse attack. To this end, our simulations are realized using schemes based on Gnutella and KazaA. Both networks are evaluated in terms of number of affected peers and their performance. ...