no auto for network interface?

[Derek Broughton]

Zach wrote:

> actually, ifplugd is not installed.  The reason the interface isn't
> configured if the cable isn't plugged in is because it's setup to use
> dhcp:
> iface eth0 inet dhcp
> So no cable, no dhcp, no configuration.

Right, of course.
> 
> As far as wireless not working with auto, why not? it's got everything
> it needs. 

I didn't think your wireless interface _could_ have everything it needs at
"auto" time.  I guess I was wrong :-(

> What is confusing however is why eth0 works even without auto?
> 
> can anyone demystify the hotplug lines?
> 
> What does this mean:
> mapping hotplug

mapping xxx

means, when an interface is brought up using "ifup iface=xxx" that mapping
stanza is used.  Hotplug automatically tries to bring up the interfaces it
controls using "ifup iface=hotplug"

> script grep

The script specified in the mapping stanza is executed with the name of the
interface as the first parameter and then the following "map" lines are
passed on stdin to the script, with the "map" stripped.  In this case,
then, it executes:
  grep eth0
  eth1
which returns a null string and nothing will happen. When the wireless iface
is brought up, hotplug will execute "ifup eth1=hotplug" and the hotplug
mapping will execute:
  grep eth1
  eth1
and return "eth1" - this makes ifup retry with the "eth1" stanza.  So I'm
still not really convinced that it comes up because of the "auto" - but
either auto or hotplug brings it up.

I still see no good reason, since ifplugd _isn't_ present, for your eth0 to
be coming up. Try blacklisting the eth0 driver module
in /etc/hotplug/blacklist.  I'm _pretty_ sure "ifup eth0" will still work,
and it should stop anything else from doing it.
-- 
derek