Ubuntu does not connect to the Internet how to do

        Ubuntu's notebook came to a LAN, plugged in the Internet cable, the network cable indicator light, but even if you don't go online, click the network connection icon to display "Network not managed". Suddenly remembered that this notebook set PPPOE (wired broadband virtual dial-up) a while ago, so I made some changes to the settings, and finally solved the problem.
1, Ubuntu's notebook came to a LAN, a little bit of recognition. Plug in the Internet cable, the network cable indicator is on, but if you don't connect to the Internet, click the network connection icon to display "Network not managed". Suddenly remembered that this notebook set PPPOE (wired broadband virtual dialing) a while ago, suspected it is the reason.
2. Press Ctrl + Alt + t to bring up the terminal.
3, type the command: cd /etc/network, transfer to the /etc/network directory, which has a file called interfaces.
4, then type the command: sudo gedit interfaces, which means to call the gedit text editor and open the interfaces file.
The last line of this file is: iface eth0 inet manual, meaning that eth0 is the web interface (on the personal computer, eth0 generally refers to the only one network cable interface), you need to set the network manually.
5, however, the current LAN, obviously the DHCP network, that is, the access to the computer needs to "automatically obtain the network" address. We add an English in front of this line of characters &################################################################################## Note that it must be in English “#”, otherwise, if you input Chinese, you will not be able to get the effect of "comment".
6, save the file, close the gedit text editor, go back to the terminal, type the command: sudo service network-manager restart, meaning to restart the network management service. Press Enter and the network is connected immediately. When you leave this LAN in the future and need to re-use the virtual dial-up, just follow the steps in steps 4 and 5, remove the added “#” and then restart the network management service.