In message <17236.1065892334@munnari.OZ.AU>, Robert Elz writes:
>    Date:        Fri, 10 Oct 2003 23:49:27 -0500
>    From:        "Brian Grayson \(home\)" <bgrayson@austin.rr.com>
>    Message-ID:  <20031010234927.A1368@cs24279-4.austin.rr.com>
>
>  |   Is it possible for me to set up my laptop so that when I plug in
>  | an Ethernet cable, it automatically invokes a script for me (to run
>  | dhclient, etc.)?
>
>Unfortunately, not yet on NetBSD, this is something that is badly
>needed, and one day I might just get irritated enough...
> 
>  |   Or is my best bet to have a shell script continue doing an ifconfig and
>  | wait for the status to change from no-carrier to active, and sleep for 15
>  | seconds between checks?
>
>If you're willing to wait a bit, just leave dhclient running on the interface
>from when you boot - it will just keep on trying (not very frequently though)
>until it succeeds.   Unfortunately, if you then get a long lease (comparativel
>y
>long compared to how long you're actually connected), it won't notice when you
>disconnect from one LAN and plug into another.
>
>And this also doesn't work if the interface doesn't exist when you boot (as in
>a plug in card or device of some kind).
>

There's supposed to be an interface to dhclient that should make that 
easier, but the documentation is sparse (arguably, non-existent) on how 
to make it work.  That doesn't solve the trigger problem -- my current 
"solution" is to restart dhclient from /etc/apm/resume -- but it should 
help with adding cards.

		--Steve Bellovin, http://www.research.att.com/~smb