A MANET is a collection of wireless nodes that can dynamically form a network to exchange information without using any pre-existing fixed network infrastructure. The special features of MANET bring this technology great opportunity together with severe challenges. In MANET, nodes can directly communicate to all other nodes within the radio communication range. In addition to the common vulnerabilities of wireless connection, an ad-hoc network has its particular security problems due to e.g. nasty neighbor relaying packets.