P2P worm has its own features and existing simulation approaches can not be used to it directly.In order to simulate large-scale P2P worm

a virtual-node based simulation approach and a double-engine based simulation architec-ture were proposed.In the virtual-node based P2P simulation solution

the data and the operation of worm nodes were separated to save computational power and storage.Therefore

large-scale P2P worms were simulated with available lim-ited physical resources in single or multiple simulating computers.In double-engine P2P simulation architecture

two en-gines

local engine and network engine

were used in simulation system.The local engine was responsible for local mes-sage processing and the network engine focused on message passing in communication network.Combined with these two engines

packet level P2P worm simulation was provided by the simulation system to enhance the fidelity and scal-ability.Experimental results showed that the novel simulation solution was practical to simulate large-scale P2P worms with high fidelity.