The OSI model is implemented for protection & security of crucial information to be accessed by hackers in the transmission process. The OSI model applies a security system like IPSec (Internet Protocol Security) incorporated in network layer & SSL (Socket Secured Layer) in transport layer. The PPTP (Point to Point Tunneling Protocol) is implemented in data link layer to develop a tunnel that is secured for exchange of data is a one way transmission and is termed as VPN (Virtual Private Network). A highly strengthened method for authentication is applied for improvising the reliability & security of VPN apart from conventional username & password technique . In the last document  we try to suggest some procedures for producing a process of authentication that is covered in two steps in the PPTP VPN that is also termed as External Database Authentication. The main advantage of this technique is that data related to user is accumulated in a précised authentication server that is comprised of a large place or organized, structurized user data through the high level of robustness & security. So this method suggests in the elaboration to the functionality of LDAP (Lightweight Directory Access Protocol) server that is hosted in over LAN of an organization, for strengthening of process of authentication of PPTP VPN. In this document, a system of OSSEC is suggested for minimizing the time of decryption & encryption in the VPN network.