Security　of　wireless　nodes　are　a　major　concern　in　mobile　ad　hoc　networks　(MANETs).　In　this　paper,　we　propose　a　scheme　for　detecting　and　blocking　malicious　nodes　in　MANETs.　Our　proposed　scheme　relies　on　specially　deployed　nodes　called　FBS　nodes　to　continuously　monitor　the　behaviour　of　the　network　nodes.　When　an　FBS　node　detects　a　node　that　exhibits　suspicious　behaviour,　it　declares　that　node　as　a　black　hole　node.　Afterwards,　all　data　and　control　messages　from　that　node　will　be　discarded.　Experiment　results　show　that　the　proposed　scheme　can　reduce　the　number　of　packets　dropped　by　malicious　nodes　with　a　low　false　positive　rate.　©　2019　Femto　Technique　Co.,　Ltd.