The Point to Point Tunneling Protocol (PPTP) is a tunneling protocol for Virtual Private Networks( VPN). The VPN protocol is not an official standard but is an initiative of Ascend, Microsoft, 3COM and US Robotic and is an extension of the Point to Point Protocol( PPP).
Unlike other tunneling protocols such as Layer 2 Forwarding( L2F) and Layer 2 Tunneling Protocol( L2TP), PPTP does not have comprehensive encryption and does not support a token-based method ofauthentication. To secure data transmission, the PPTP protocol has a 40-bit or 128-bit RC4 algorithm and the possible use of RADIUS password logons with the PAP protocol or the CHAP protocol.
PPTP can handle the IP protocol, Internetwork Packet Exchange Protocol( IPX), DECnet, AppleTalk, NetBIOS and NetBEUI. For this purpose, the multi-protocol PPP is encapsulated in a tunnel. For this purpose, the modified version of GRE V2 (version 2 of Generic Routing Encapsulation) is used. The PPTP protocol is used to secure dial-up connections, but also LAN-LAN connections. A PPTP tunnel can be established over an existing IP connection. PPTP cannot establish multipoint connections, but only point-to-point connections, albeit in any locations in the virtual private network (VPN).