IPSec over L2TP
Virtual Private Network
The two Hybrid Processes IPSec over L2TP (IP Security over Layer 2 Tunneling protocol (RFC 2888), and SSL over L2TP (L2Sec). combine the advantages of the advantages of Layer 2 and Layer 3 Tunneling.
The IPSec over L2TP Process supports all forms of remote access and is very effective in large point-to-point environments. This means connecting large numbers of mobile and stationary PC workstations to the central system using dynamic IP addresses. Attacks on the remote client and man-in-the-middle-attacks are rendered impossible through the use of personal firewalls and the use of smartcards for user authentication.
But be careful!
In order compensate for IPSec protocol deficiencies some manufacturers have implemented proprietary protocols which means that the original IPSec standard has been diluted ad absurdum.