What do pptp and gre ports do?

[1665]

What do pptp and gre ports do? Hi I created a rule (with help) to allow users to connect to a VPN. I had create a rule from inside to outside on ports pptp and gre (44) and and outside to inside on just port gre, but I just want to understand the process of why these ports where needed etc as I need to explain this to someone....

Kind Regards

A

 

[neutec]

Short for Point-to-Point Tunneling Protocol, a new technology for creating Virtual Private Networks (VPNs) , developed jointly by Microsoft Corporation, 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.
A PPTP is used for Windows 2000 VPN connector out going and GRE would be the cisco VPN tunnel out.