Wish: should support PPP dial-on-demand

Binary package hint: network-manager

It would be nice if network-manager (well, ok: "the Ubuntu network access structure" :) would support dial-on-demand for dialup connections. That would make it possible to use dialup connections with minimal hassle.

Background: I am currently administrating a home PC which is connected to the net via ISDN, using a call-by-call internet access. I have manually set up dialup with pppd, but it seemed quite annoying that the use has to click an icon whenever she wants to go online. So I have configured pppd for dial-on-demand, which means that the user can just start the computer, click on the Firefox icon, and start surfing. As an extension, a script continually runs (sleeps) in the background that switches between a day and a night call-by-call number (through this script, internet access rate is constantly at 0.5 EUR cent per minute). The phone bills haven't shown any high costs from the dial-on-demand, and I suppose it has in fact saved money because the line was disonnected automatically when idle (instead of ticking on if the user forgets to disconnect).

There are some more things to take care of for proper dial-on-demand support:
- network services on the machine should be configured for minimal internet access (IIRC I tweaked Samba so it doesn't send broadcasts over ppp0)
- software updates should be integrated nicely (best solution: good traffic shaper so packages can be downloaded while user is surfing)