Point-to-Point Tunneling Protocol (PPTP) is an extension of the PPP protocol. PPTP can only be used over TCP/IP connections to create a single tunnel, it does not support header compression or provide authentication. For authentication IPSec can be used, Microsoft Point-to-Point Encryption (MPPE) is used for encryption.
To use a PPTP VPN over a firewall the following ports must be open :
| UDP 1723 (PPTP) |
| UDP 1701 (L2TP) |
Another tunneling protocol is the Layer 2 Tunneling Protocol (L2TP) which only encapsulates packets, it does not encrypt data. L2TP can be used over IP connections but also over Frame Relay, ATM and X25 to create multiple tunnels between end points. It also supports header compression and tunnel authentication. For encryption, IPSec can be used.
| Connection manager support for VPN server selection. (WH1321N020601) |
| VPN client (L2TP/IPSec) for Windows 95/98/ME/NT 4.0 |
Last update : 16 July 2002