Mobile ad hoc networks have wireless links and work independently of fixed infrastructure. They are self-organizing and self-configuring. The wireless nodes operate both as communication end-points as well as routers, enabling multi-hop wireless communication. The wireless devices imply limited power resources and bandwidth. Network topology may change rapidly due to mobility, interference, physical obstacles on the path and so forth. Application areas range from conference hall networks to ad hoc networks for emergency and rescue operations and military tactical use. The wireless and dynamic nature of Mobile Ad hoc NETworks (MANETs) leaves them more vulnerable to security attacks than their wired counterparts.