MANETs are the wireless networks of the mobile computing devices with no support of any fixed infrastructure. The mobile nodes use any of the radio technology like Bluetooth, IEEE 802.11 or Hiperlan for directly communicating with each other. The nodes behave as hosts as well as routers. The security challenges in MANET arise due to its dynamic topology, vulnerable wireless link and nomadic environment. Many approaches have been proposed to overcome the same. In this paper, the authors target at designing an effective and robust technique namely Nimble message authentication protocol and later on using it with roaming honeypots so as to doubly ensure freedom from threats and attacks like man in the middle attack and replay attack, thereby assuring security in MANETs.