Peer-to-peer （P2P） networks aggregate enormous storage and processing resources while mini- mizing entry and scaling costs. Gnutella-like P2P networks are complex heterogeneous networks, in which the underlying oveday topology has a power-law node degree distribution. While scale-free networks have great robustness against random failures, they are vulnerable to deliberate attacks where highly connected nodes are eliminated. Since high degree nodes play an important role in maintaining the connectivity, this paper presents an algorithm based on random walks to locate high degree nodes in P2P networks. Simula- tions demonstrate that the algorithm performs well in various scenarios and that heterogeneous P2P net- works are very sensitive to deliberate attacks.
