Handle for things to do when network becomes available

[Koen Vermeer <k.a.vermeer@tnw.tudelft.nl>]

Hi,

What is the right location to do things that should be done when an
Internet connection becomes available? By that, I mean things like
running ntpdate, flushing the mail queue, maybe do some synchronization,
etc. I was considering an 'up do-stuff || true' statement
in /etc/network/interfaces, but I don't really like that approach
because it requires me to have the same lines for several interfaces
(the network may be ethernet, or wireless, or...).

My best guess is something that is called anytime a route gets set up,
but I wouldn't know how to do that. Any ideas?

Koen