Networking >> VPN >>  What are the common VPN technologies

IPSec ----- Internet Protocol Security Protocol (IPSec) provides enhanced security features such as stronger encryption algorithms and more comprehensive authentication. IPSec has two encryption modes: tunnel and transport. Tunnel mode encrypts the header and the payload of each packet while transport mode only encrypts the payload. Only systems that are IPSec- compliant can take advantage of this protocol. Also, all devices must use a common key or certificate and must have very similar security policies set up. For remote-access VPN users, some form of third-party software package provides the connection and encryption on the users PC. IPSec supports either 56-bit (single DES) or 168-bit (triple-DES) encryption. PPTP/MPPE --------- PPTP was created by the PPTP Forum, a consortium which includes US Robotics, Microsoft, 3COM, Ascend, and ECI Telematics. PPTP supports multi-protocol VPNs, with 40-bit and 128- bit encryption using a protocol called Microsoft Point-to-Point Encryption (MPPE). It is important to note that PPTP by itself does not provide data encryption. L2TP/IPSec ---------- Commonly called L2TP over IPSec, this provides the security of the IPSec protocol over the tunneling of Layer 2 Tunneling Protocol (L2TP). L2TP is the product of a partnership between the members of the PPTP forum, Cisco, and the Internet Engineering Task Force (IETF). Primarily used for remote-access VPNs with Windows 2000 operating systems, since Windows 2000 provides a native IPSec and L2TP client. Internet Service Providers can also provide L2TP connections for dial-in users, and then encrypt that traffic with IPSec between their access-point and the remote office network server.