Sybil attack is the most threatened issues found in the network which will cause consumption of more network spaces. Preventing the Sybil attack is difficult task where every fake identity generated by the attacker will looks like genuine id to the other nodes. In our previous work Sybil attack detection is performed through presenting an approach named Latency and Power aware Reliable Intrusion Detection System (LP-RIDS). However, this methodology failed in preventing Sybil attack occurrence which is focused in this work. In this work, Sybil attack prevention is ensured by introducing Privacy concerned Anonymous Authentication Method (PAAM). In this work, secondary cluster head selection is accomplished through Hybrid genetic with ACO algorithm. Here the secondary cluster head selection is done with the concern of higher energy value. The node that have energy lesser than threshold will not be considered for the Sybil node attack detection. And then anonymous authentication is performed to detect the Sybil attack. This is done by initializing the registration phase where all cluster members will share their temporal identity with the cluster head. Here temporal identity is generated randomly by each cluster member which is not possible to guess by other nodes. By using this temporal identity cluster head will generate the secret key which will be divided into two shares. Here first share will be given to the corresponding cluster member and second share will be given to the secondary cluster head. Thus no node can identify the privacy information of other users. This secret information will be utilized for the authentication process. Secondary cluster head will verify the cluster members at the time of data communication with the help of first share of secret key. This research method avoids the Sybil attack presence accurately. NS2 is greatly utilized in this research for validating the proposed techniques which offers better result when compared with prevailing work. The overall implementation of the research work is done in the NS2 from which it is proved that the proposed techniques tends to provide better outcome than existing work.