A technology for creating Virtual Private Networks (VPNs) , developed jointly by MicrosoftCorporation, U.S. Robotics, and several remote access vendor companies, known collectively as the [PPTP] Forum. A [VPN] is a private network of computers that uses the public Internet to connect some nodes. Because the Internet is essentially an open network, the Point-to-Point Tunneling Protocol ([PPTP]) is used to ensure that messages transmitted from one VPN node to another are "secure". With [PPTP], users can dial in to their corporate network via the Internet. 

  

 If you want to support this under Linux, get [PoPToP|http://www.poptop.org/]. It starts a pppd in the correct place; you might be interested in the [MPPE] patches.