Yesterday it worked.
Today it is not working.
Windows is like that.
So are networks, oddly enough.
There are many many ways you can set up a tunnel between two networked hosts. The MetaNet is one such example of a tunnel - it is a multi-point tunnel.
Most tunnels are point-to-point. Some examples are:
- SSH Tunnels. Very easy to set up in user space. See SSHNotes for information.
- IPSec - The 'secure' way to set up tunnels. Kinda broken under Linux atm.
- L2TP - Layer 2 Tunnelling Protocol
- GRE - Generic Routing Encapsulation. See GRETunnel for information
- PPTP - Point To Point Tunnel Protocol
- IPIP - IP over IP Tunnel
You may want to authenticate your users against another machine; look at RADIUS and TACACS.