The development of new protection mechanisms for reliable and secure electronic commerce is a very important current in scientific investigation. This paper describes the software environment for the multi-agent simulation of defense mechanisms against Distributed Denial of Service (DDoS) attacks developed by the authors. The agent-based approach suggested for the modeling and simulation of defense mechanisms against DDoS attacks is considered. According to this approach, the cybernetic opposition of malefactors and security systems is represented by the interaction between two different teams of software agents - the malefactors' team and the defense team. The main components of the software environment are outlined. One of the numerous experiments on protection against DDoS attacks is described in detail. The developed environment is based on OMNeT++ INET Framework.