Wireless networks, in particular Mobile Ad-hoc NETworks (MANETs) have revolutionized the field of networking with increasing number of their commercial and military applications. Security on the other hand, is now an essential requirement for these applications. However, the limitations of the dynamic, infrastructure-less nature of MANETs impose major difficulties in establishing a secure framework suitable for such services. Security for MANETs is a dynamic area of research. Most of the traditional routing protocols proposed for MANETs are focused on routing only not on the security aspects. As in traditional wired networks, wireless networks also require security. Unlike the wired networks, where dedicated routers, servers control the network, in MANETs nodes act both as terminals and also as routers for other nodes.