In recent years, Mobile Ad-hoc NETworks (MANETs) are used widely in many applications. In information security, intrusion detection is the act of detecting actions that attempt to compromise confidentiality, integrity or availability of resource. Most intrusion detection systems for mobile ad-hoc networks are focusing on either routing protocols or its efficiency but fails in addressing security issues. Intrusion can be detected in many ways by collecting the system log files, network packets etc. An IDS collects this information and analyze audit data looking for irregular activities or intrusion activities and raises an alarm.