Point-to-Point Tunneling Protocol

The Point - to-Point Tunneling Protocol ( PPTP) is a network protocol based on the Internet Protocol and is used to build a Virtual Private Network (VPN ) in a computer network.

With PPTP, a VPN is created by a tunnel for the Point-to -Point Protocol is formed. It leaves room for every conceivable form of authentication and encryption. The initialization is then carried out via TCP port 1723, and the data flow control according to the Generic Routing Encapsulation Protocol.

PPTP was developed by a manufacturing consortium, which included 3Com and Microsoft. In June 1996, it submitted the first draft at the Internet Engineering Task Force. The first implementation was part of the Microsoft Windows NT 4.0 and also available for Windows 95.


Published in 1998, the security expert Bruce Schneier, an analysis of the implementation of Microsoft, which revealed a number of weaknesses. Most of them were not related to the actual implementation of PPTP, but in the implementation of authentication and encryption. Neither of these but had to be overcome in order to trigger a blue screen over PPTP. Microsoft immediately improved both the implementation of the Challenge Handshake Authentication Protocol, as well as the Microsoft Point - to-Point Encryption, but maintained that the user is determined by the quality of his password, how safe is both.

2012 presented an encryption expert Moxie Marlinspike one web site that you want, any VPN and wireless connections within one day crack. The magazine c't was able to successfully apply the process and therefore spoke of the " death knell for PPTP ".


Since PPTP was published in 1999 as RFC 2637, it has been implemented for almost all operating systems. So there, among other things, a PPTP client for OpenBSD, FreeBSD, NetBSD, Mac OS X and iOS. Linux supports PPTP since kernel version 2.0. Many modern routers and firewalls have integrated a PPTP server.

Among other things, in Austria, Italy, Belgium, and the Netherlands, the PPTP protocol is used above over PPP ATM for DSL connections. In Germany and Switzerland, however, most PPP over Ethernet is used.