原文：http://askubuntu.com/questions/71159/network-manager-says-device-not-managed
wired device not managed
Most probably your interface appears in /etc/network/interfaces. By default, NetworkManager does not manage interfaces that appear in /etc/network/interfaces. You can change this behaviour.
To do this – in a terminal:
sudo nano /etc/NetworkManager/NetworkManager.conf
change the line managed=false to managed=true
Save, stop and start network manager:
sudo service network-manager restart
Alternatively, you can remove the interface from /etc/network/interfaces.
backup the current interfaces file:
sudo cp /etc/network/interfaces /etc/network_interfaces_backup
Then open the file:
sudo nano /etc/network/interfaces
Delete everything in that file and copy and paste the following:
auto lo
iface lo inet loopback
Save, stop and start network manager:
sudo service network-manager restart