Now-a-day, it is no longer optional to have security solutions even inevitable for every kind of organizations and individuals. There are number of generic tools which are common for organizations as well as for individual users to provide security which includes; anti-spam, anti-virus etc., and network security have become essential issue in MANET. Security is one of the main issues in the MANET especially with respect to size and complexity of the network. This paper is to discuss different aspects of security in MANET (e.g. multi-layer intrusion detection technique in multi hop network of MANET, security problems relates between multi-hop network and mobile nodes in MANET etc).