How to be sure my Mac is fully disconnected? On many occasion thinking that my Mac was disconnected from any form of network (with or without wire), I discovered that in fact it was
confortably chating at full speed with the rest of the world through
a forgotten connection. Typically:

tcpdump -i en1


displayed a high speed movie about domain, bootpc, http, netbios, https, 5223 (unassigned)… trafics.

For the wireless side, there is a nice function to be aware that a Mac
is connected or not: the Wi-Fi icon in the menu bar.

But for infrared, Bluetooth, Ethernet, MacOS X seems to miss the same usefull and simple function.



Is there a trustable software or method to be sure that a Mac if fully disconnected from any form of network?

I would be mostly interested by something as small and as visual as the Wi-Fi icon in the menu bar.
This software should accomplish what you're looking for: "Ethernet Status"
There might be free alternatives, this is the first one I came across.