PPTP At the present time the most common protocol vpn firefox is the protocol the two-point tunnel connection or a Point-to-Point Tunnelling Protocol - the PPTP. Developed it companies 3Com and Microsoft with the aim before the representation secure remote access to corporate networks via the Internet . PPTP uses the existing open standards TCP / IP and to a large extent relies on an outdated protocol the two-point connection PPP . In practice PPP so and stays communication prot about Session Connection PPTP. PPTP creates a tunnel through the network to NT - with the recipient's server and transmits PPP packets of the remote user through it . The server and working station using virtual private network and do not pay attention on the fact , how securey and accessible is the global network between them . The completion of the session connection on the initiative of the server , in contrast, by the specialized server remote access , allows a local network does not pass the remote users of the limits system safety of the Windows NT Server. Server NT Although competence protocol PPTP applies only to devices , operating under the control of Windows, it offers companies the opportunity to interact with existing network infrastructures and not to cause harm to their own system security . In this manner , a remote user can connect to the Internet with the help of the local provider of an analog telephone line or channel ISDN and establish connection with the server NT. If this company does not have to spend large sums on the organization and maintenance of a pool of modems , which provides services to remote access . Further , the work of the RRTP is considered . PPTP encapsulates packets IP for transmission on IP - with hildren . Clients PPTP using the port of destination for the creation of sound control tunnel connection . This process occurs at the transport layer of the OSI model. After the tunnel is created, the client computer and the server begin to exchange service packets . Encapsulating Data Steps In addition to the control compound PPTP, which ensures operability ka n ala , creates a connection for forwarding by the tunnel data. Encapsulating data before forwarding through the tunnel there is some other way than with a conventional transmission . Encapsulating data before sending it into the tunnel involves two steps: 1. First, create information of the PPP. Data flows from top to bottom , from the OSI application layer to the data link layer . 2. Then the obtained data are sent upwards by the model OSI and encapsulated protocols of upper layers .

Encapsulating data before sending it into the tunnel involves two steps.