I was configuring DHCP Server, after configuration successful i restarted my server then All Ethernet ports went down, i check Network Manager graphically it shows "Device not managed" then i checked it from terminal using
sudo /etc/init.d/networking restartIt gives me this message
* Running /etc/init.d/networking restart is deprecated because it may not enable again some interfaces
* Reconfiguring network interfaces...
/bin/sh: cannot open /etc/iptables_rules: No such file
Failed to bring up eth0.
This was the issue i got.
Edit the file "/etc/NetworkManager/NetworkManager.conf"
Change managed=false to managed=true
And ececute this in terminal.
sudo killall NetworkMangerNow we can configure our ethernet/wify interface.