4. SSH vs. other VPN solutions

The role of a Virtual Private Network (VPN) is to extend a private network by using a public network, for example, in a secure way. A VPN makes it possible to link several entities or sites, and to integrate roaming users into a private network. Most VPNs are based on the use of tunnels, which rely on the use of a public network, where exchanges are secured. The way this works is to encapsulate the data to be transported in the packets of the protocol creating the tunnel.

Over the last decade, a number of security protocols have been developed and accepted by the Internet developer and user communities. One example is the PPTP protocol, developed by Microsoft, which installs a secure tunnel via PPP between mobile workstations (mainly running on Windows) and the intranet. However, for other uses, such as linking several intranets via a secure network, the IPSec protocol...