> > > and lisen for arp packets, and deduce the IP network number from that.
 [...]
> >
> > (Hm.  If I were to go this route, though, wouldn't tcpdump work?  I seem
 [...]
>
> tcpdump could work, you just have to parse the input. But as you said you need
> some kind of timeout; it may not be easy to implement using tcpdump.

Parsing shouldn't be that hard.  Just pull out $2 and/or $4 with awk.

But, the whole idea of a passive approach seems the wrong way around
for my situation, anyway.

I guess that when I have time, I'll begin modifying my
/etc/rc.d/network script.  What I want to do shouldn't be too complicated.


  ``I probably don't know what I'm talking about.'' --rauch@math.rice.edu