VPN – Site to Site / Host to Site / Host to Host
- IPSec – Provides authentication & data encryption – Operates at the network layer
- GRE – Generic Routing Encapsulation, encapsulates the data, operates at network layer & is a CISCO technology.
- SSL VPN – Main use is eCommerce, uses cryptography (secure authentication & communications)
- PTP / PPTP – Port 1723 UDP, Point to Point, layer 2, PPTP has been largely replaced by L2TP with IPSec.