I updated a virtual machine running Ubuntu server 15.04 to the just released new stable 15.10.
There were no apparent problems, but after reboot the machine lost its network connection.
lspci showed the correct card and
lsmod proved that the driver had been loaded.
Hints about editing or removing
/etc/udev/rules.d/70-persistent-net.rules did not succeed (still no network, no new file), the famous
/lib/udev/write_net_rules did not even exist.
I don't have much clue regarding udev and systemd, so it took me some time to find in /sys/class/net that the network interface name changed. It became
ens32, which was renamed from
eth0. After I changed
/etc/network/interfaces network communication was enabled again.
But – why does this happen at all? And if it happens, shouldn't the interfaces file be updated automatically?
Now that I deleted the virtual network card and created another one,
eno16777728, which is not so, uhm, nice.
Should this behaviour (at least that of the upgrade procedure) be reported as a bug?
/etc/udev/rules.d/70-persistent-net.rules obsolete now? And (although only partly related) what about
Edit – additional question (after accepted answer)
The dependency of
/etc/network/interfaces from the actual interface name bothered me. I tried a new installation of *ubuntu in another virtual machine. To my surprise,
/etc/network/interfaces contained a reference to the loopback device only. However, with my original VM this change prevented the network to come up. So what else do I need to change?
Well, from another test I found that a new Ubuntu Server has the network interface card in
/etc/network/interfaces, while XUbuntu has not. Maybe it is using
network-manager or something else.