After I upgraded from Ubuntu 16 to Ubuntu 18, my network configuration seems to be a broken mess.
Linode
Linode Staff
I did an in-line upgrade from Ubuntu1 16 to Ubuntu 18 a while back and everything went smoothly enough. Later on, I needed to change my IP address, and now I can't contact my Linode.. What happened?
2 Replies
Hi there,
Since your network interface is not in service, you'll need to connect to your Linode with Lish:
https://www.linode.com/docs/networking/using-the-linode-shell-lish/
There are some differences in the way your system's networking settings are configured between Ubuntu 16 and Ubuntu 18. These differences don't always work properly with Linode's Network Helper. Network Helper can be turned on or off in your Linode's Configuration Profile, and you can read a little bit about how it works here:
https://www.linode.com/docs/platform/network-helper/
In short, when Network Helper detects Ubuntu 18, it updates the following file's network settings:
/etc/systemd/network/05-eth0.network
Ordinarily, this would be fine because this is where Ubuntu 18 typically stores its network settings.
Ubuntu 16, on the other hand, stores it's network configuration at the following:
/etc/network/interfaces
This problem arises because by default, after upgrading from Ubuntu 16 to Ubuntu 18, your system STILL USES the /etc/network/interfaces file to setup its network, but Network Helper will only update the systemd file at /etc/systemd/network/05-eth0.network.
There are two ways to fix this: Enable systemd's networking in Ubuntu 18. Or manually configure networking in /etc/network/interfaces
In cases where your network settings are uncomplicated, you might it preferable to just edit /etc/network/interfaces and run ifdown -a && ifup -a to restart networking. You might want to disable the 'Auto-Configure Networking' setting in your Configuration Profile to avoid confusion, but it won't really matter.