Just follow these steps:
- Check that the ethernet cable is properly connected
- Open Terminal
- Run sudo pppoeconf
- Enter root password
- Answer all the question that will be asked with an answer "Yes"
- Finally type pon dsl-provider 開始撥號
To stop connection run poff dsl-provider
指定撥號網卡
sudo vi /etc/ppp/peers/dsl-provider
plugin rp-pppoe.so eth2
pon命令詳解
1.pon命令不帶參數，首先檢測運行/etc/ppp/ppp_on_boot文件，如果不存在就會去 /etc/ppp/peers/文件夾下尋找啟動文件。
2.pon命令帶參數，pon myisp；就會使用/etc/ppp/peers/myisp文件
sudo plog查看撥號日志
Sep 28 16:14:30 brian pppd[18211]: CHAP authentication succeeded: Access granted
Sep 28 16:14:30 brian pppd[18211]: CHAP authentication succeeded
ifconfig ppp0 查看連接信息
ps -aux | grep ppp 查看運行的進程
sudo kill -9 2121 殺掉相應進程
參考：
https://askubuntu.com/questions/406300/how-to-connect-to-internet-using-wired-pppoe-connection
https://blog.csdn.net/selous/article/details/55520765