Configuring networking interfaces
Finding network interface
# See a list of networks available ls /sys/class/net # See if your network is disabled sudo lshw -C network ip addr
Turn down a network
sudo ip ls dev en0 down sudo ifdown en0
# Enable interfaces sudo ifup -v eth0
The file to edit to configure networks
sudo nano /etc/network/interfaces
Try booting in recovery and then enabling networking. This was the easiest way for me to get ethernet to work. From GRUB, select Advanced Options and boot in recovery mode.
# Commands systemctl status networking.service # restart networking service networking restart sudo /etc/init.d/networking restart
If you don’t see eth0 but something like enp0s25, it’s because of Predictable Network Interface naming]() which is a part of systemd/udev. Basically it names the interface based on it’s hardware location. enp0s25 means PCI bus 0 slot 25. You can get an idea of the hardware location with
lspci. You can also check the logs for lines like
Figure out which interface has the cable attached
ip link sudo ethtool enp3s0 sudo ethtool enp0s25
sudo nano /etc/network/interfaces
# The loopback network interface auto lo iface lo inet loopback # The primary network interface auto enp3s0 iface enp3s0 inet dhcp
sudo ifdown enp3s0 && sudo ifup -v enp3s0
# Enable ethernet sudo ifconfig eth0 up sudo dhclient eth0
# Configure Google Public DNS echo "nameserver 126.96.36.199" > /etc/resolv.conf sudo ifconfig enp0s25 down sudo ifconfig enp25 up
Network manager says network not managed
Note: This happened to me on a fresh Ubuntu Sever 16.10 install from a CD. Ubuntu Desktop was installed separately later, and in it the Network Manager said ethernet networks were unmanaged. Didn’t have a wifi card on the system.
This is a known bug on Ubuntu 16.10. The Network Manager refuses to manage ethernet and bluetooth connections. Someone decided to not let Network Manager manage these interfaces except in a desktop edition (possibly because servers normally uses the ifupdown mechanism to manage networking).
On desktop images we want NM to manage everything, thus the installer creates
/etc/NetworkManager/conf.d/10-globally-managed-devices.conf. But on a server, container, or similar environment we do NOT want NM to suddenly take over existing connections from netplan, networkd, or ifupdown – there it should be restricted to wifi and 3G.
10-globally-managed-devices.conf is the default config file to explicitly unmanage anything that is not wifi or wwan (meaning we definitely want NM to manage wifi and mobile data; and probably don’t want it to touch wired in many cases).
This file installed under
/usr/lib/NetworkManager/conf.d/ has the following content by default:
that unmanages all network interfaces except wifi and wwan, thus bluetooth interface and ethernet interface are all unmanaged by default.
First try running the following command:
nmcli d sudo nmcli dev set enp8s0 managed yes
If you get the error message:
Error: Device 'enp8s0' not found.
Try running the command below:
ip link show
and look for a device name similar to enp8s0 and substitute it in the original command.
Create a blank file called
/etc/NetworkManager/conf.d, if one doesn’t already exist.
# Ubuntu 16.04 # create blank `10-globally-managed-devices.conf` under `/etc/NetworkManager/conf.d` # https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1638842 touch /etc/NetworkManager/conf.d/10-globally-managed-devices.conf # remove /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf rm -rf /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf
Alternatively, you can edit the
10-globally-managed-devices.conf to change the value for
# Ubuntu 17.10 cp /usr/lib/NetworkManager/10-globally-managed-devices.conf /etc/NetworkManager/10-globally-managed-devices.conf nano /etc/NetworkManager/10-globally-managed-devices.conf # change the value "unmanaged-devices" to none
Afterwards, restart Network Manager
# restart Network Manager sudo service network-manager restart sudo systemctl restart NetworkManager
Check the logs
tail /var/log/syslog cat /var/log/syslog | grep "eth" | tail -50