The spread of 1-10 Gbps technology has in recent years paved the way to a flourishing landscape of new, high-bandwidth Internet services. At the same time, we have also observed increasingly frequent and widely diversified attacks. To this threat, the research community has answered with a growing interest in intrusion detection, aiming to timely detect intruders and prevent damage. We believe that the detection problem is a key component in the field of intrusion detection. Our studies, however, made us realize that additional research is needed, in particular focusing on validation and automatic tuning of Intrusion Detection Systems (IDSs).