Loopback address mapping is the use of unused loop-back IP addresses to interface a machine with one or more tunnels
Hosts File - the machine's hosts file is edited to bind a remote host to a single loop-back address in the 127.1.0.0 range.
TCP Servers - tcp listeners are set up on the user's machine, one listening per configured tunnel to a remote service.
No Virtual Network Adapter - this approach means that no virtual network adapter is needed. That closes some security flaws that comes with a virtual network adapter, and removes the need for any TCP/IP protocol processing.