Vehicular Ad-hoc network are wireless networks where all the vehicles from the nodes of the network. It is for the driver comfort and road safety, the inter-vehicle communication provide them. Sybil attack is such a critical attack where the multiple messages are created by the attacker and are sent to other vehicles with different Ids each time. This makes the other nodes get confused such that the nodes assume the messages are arriving from other nodes. This communication in the two forms is unidirectional or bidirectional fixed infrastructure. In the recent times, various techniques have been proposed for the detection of malicious nodes from the network. The proposed technique is based on monitor mode and signal strength based technique. The simulation is been performed in NS2 and results shows that purposed technique shows good results in terms of various parameters.