Detecting ethernet gadget connections

[Daniel Benoy]

I'm working on a script that will detect which network interfaces are connected and mess with the routing accordingly, but I'm having trouble detecting whether my USB ethernet gadget connection is up or down.

----
ethtool when it's up:
lisa:~# ethtool usb0
Settings for usb0:
	Link detected: yes

ethtool when it's down:
lisa:~# ethtool usb0
Settings for usb0:
	Link detected: yes
----

Unlike on the host side, the usb0 interface doesn't appear and disappear, allowing udev scripts to bring up/down the interface.

Anyone know if there's a way to detect that a network connection has actually been established?

-- 
Daniel Benoy
http://daniel.benoy.name