Connecting a cable

[David Abrahams <dave boost-consulting com>]

Today I booted my machine with no ethernet cable connected and the
following in /etc/network/interfaces:

  iface eth0 inet static
  address 192.168.188.19
  netmask 255.255.255.0
  gateway 192.168.188.1

I connected wirelessly.  

Later I connected a cable.  No reconnection to the wired connection
from NM, and no wired connection in the applet menu.  I looked at
/etc/network/interfaces and see the above, which explained it.

So next, I commented out the eth0 stuff in /etc/network/interfaces.
Disabled networking and enabled it in NM applet.  Still no wired
connection available.

Next I stopped and restarted NetworkManager and
NetworkManagerDispatcher.  Still no wired connection available.  I've
seen this before.  How do I make the previously-unused wired
connection visible to NM?

[Furthermore, NM won't connect wirelessly, even after toggling the
wireless kill switch.  My usual simultaneous dhclient + wpa_supplicant
trick seems to be the only way I can connect now.]

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com