How can I create in Network Manager, multiple wired lan connection configuration for the same wired card? I use to move between a lot of offices where I need to change my network config (IP, Mask, ecc) is it possible to create or save different configurations for the same network card and activate the right one time by time?
Right click on the NetworkManager icon. In the "wired" tab, open up your existing connection ("Auto eth0") and copy the Device MAC address so you can put it in the new configuration profile. Then select "Add" to create a new connection profile for your wired connection.
After this, I believe all the profiles you've created should show up as options in your network list when you plug in a cable.
On Ubuntu 11.10 with Gnome 3, you will only get the stripped down version of the gnome control panel's network manager (like when you are running
gnome-control-center network from terminal).
If you want to configure a second (or more) wired network connections, run
nm-connection-editor. It lets you add new connections.