VTun provides a method for creating Virtual Tunnels over TCP/IP
networks and allows to shape, compress, encrypt traffic in these
tunnels.

Supported types of tunnels are: PPP, IP, Ethernet and most other
serial protocols and programs.  VTun is easily and highly configurable,
it can be used for various network tasks like VPN, Mobile IP, Shaped
Internet access, IP address saving, etc.  It is completely a user
space implementation and does not require modification to any kernel
parts.