On Demand VPN

[Kevin Fries]

Back in the "Good Ol' Days" (wink wink) there used to be a tool that 
would start on boot that would identify your environment at startup.  
You could write a test that would go (pseudo code, not actual test code) 
something like:

    * If my IP is in the 192.168.5.x subnet, then location=home

    * If my IP is in the 192.168.1.x subnet && hostname of 192.168.1.10 
== "snoopy", then location=office

    * if my IP is in the 192.168.1.x subnet && hostname of 192.168.1.1 
== "mail", then location=clientA

Well you get the idea, you could set your network settings appropriate 
to your location.  This was a great tool for consultants, and I used to 
use it on the laptop I used when consulting.  But that was in the days 
before Network Manager, Wicd, and all the other udev based network 
management tools.

Today, I find myself with a similar problem, but on the surface, it is 
far more simplistic.  99% of the time, Network Manager in my Ubuntu 
11.04 does exactly what it is supposed to do.  I also have a VPN set up 
to my office, that is working correctly, but due to restrictions on the 
VPN from the company, is less than optimal.  But Network Manager is far 
more of a black box than the old ifup/down ever was, so I thought I 
would ask all of you.

What I would like:
   * When I am in the office, I just want Network Manager functionality

   * When I am not in the office, the default is normal Network Manager 
functionality

   * When I am not in the office, and I try to go to a location (by name 
or IP) that is within a specified range, I want the VPN to activate, and 
route all traffic only for the office over it, while allowing all other 
traffic to go out via the normal, primary, connection.

Anybody have any ideas on this?

Kevin