Recently cyber security has emerged as an established discipline for computer systems and infrastructures with a focus on protection of valuable information stored on those systems from adversaries who want to obtain, corrupt, damage, destroy or prohibit access to it. Several information security techniques are available today to protect information systems against unauthorized use, duplication, alteration, destruction and virus attacks. An Intrusion Detection System (IDS) is a program that analyzes what happens or has happened during an execution and tries to find indications that the computer has been misused. This article presents some of the challenges in designing efficient intrusion detection systems which could provide high accuracy, low false alarm rate and reduced number of features. Finally, we present how some of the computational intelligence paradigms could be used in designing intrusion detection systems in a distributed environment.