Ok, I am an experimented Debian users, using it since 1 years full time, so no "n00b" question here.
Here's the case : yesterday, I updated my whole Debby box using SSH... soon, the connection crashed. I was unable to reach the box by any ways so I thought "What the hell, it crashed?". So I rebooted the damn thing.
It wasn't crashed, in fact I find later when I moved from my desk to go take a look at the box that Eth0 was using the old useless ip 188.8.131.52. That's is really strange since this is an ip I was using loong loong ago, something like 1 years ago and that have been changed to... ehh... I'll say 192.168.0.1.
So I looked deeper and I found that the file /etc/interfaces have been changed by Debian during the update. My "good" files still exists and was renamed "interfaces.1".
This is very strange, since 184.108.40.206 wasn't used for a while and was removed from any config file, it is just like Debian saved somewhere the network first configuration (the one that have been done during the installation), not a in a common config files, and then used this configuration during the update.
I am not very sure what package caused this old config to wake up, but in updated package are dpkg and dpkg-dev, that are both very suspicious to me
This is not as big trouble, however I don't want to see this box offline each time I update it. If someone could tell me what caused that and why, I'll be verr pleased