Security is the process of maintaining an acceptable level of perceived risk. Nowadays, security management has become an important issue that must be considered carefully. Security is required in any organization/institute to protect its hardware, software and data resources against known or sometimes unknown resources [1]. These unknown resources cause risk to our system. Unknown resources can be inserted into system intentionally or unintentionally. We focus on one critical security management issue that is intrusion detection. So, we propose an approach for security management using intelligent agent model [2]. This model provides a flexible integration of multi-agent technique in a classical network to enhance its protection level against inherent attacks. A multi-agents system, which aims at detecting intrusions in a complex network. Multi-agents systems provide a suitable solution. So, we applied a well-known multi-agent methodology and showed that it is useful for real-life application [2]. We also used agent knowledge, with BDI theoretical model.