Network simulators serve a variety of purposes. Compared to the cost, time, and effort involved in setting up an entire test bed containing different types of network devices, network simulators are relatively fast and inexpensive. Computer intrusions are occurring almost routinely and have become a major issue in our networked society. Every organization is faced by the big challenge of selecting an intrusion detection system and testing its abilities. Therefore, it is worthwhile to investigate the possibility of implementing and thoroughly testing intrusion detection systems using network simulators. In this paper, we report our experience with implementing and testing intrusion detection systems using OMNeT++ simulator. We highlight how OMNeT++ is harnessed to test and evaluate the intrusion detection system in terms of detection accuracy and performance.