18.04 - does it force netplan or can I still use resolved.conf?

Question

I kept getting timeout errors on 18.04 Bionic Beaver, until I switched to OpenDNS using these commands

sudo rm -f /etc/resolv.conf 
sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf 
sudo nano /etc/systemd/resolved.conf
# with body 
nameserver 208.67.222.222

Should I really be doing this OpenDNS configuration with Netplan? I tried the following but it doesn't work.

# Create a netplan file
sudo vi /etc/netplan/50-cloud-init.yaml

.

# Put this in the body
nameservers: 
    addresses: [208.67.222.222, 208.67.220.220]

I also tried this syntax in the body to no avail, but maybe it because I'm on wifi and I called out 'ethernet'??? wlo1 is my wifi logical name when I sudo lshw -C network.

network:
  ethernet:
    wlo1:
      nameservers:
        addresses: [208.67.222.222, 208.67.220.220]

Solution 1

You first have to make a decision to use NetworkManager or systemd-networkd. If you connect wi-fi to various wireless networks, then NetworkManager is probably the better choice. systemd-networkd is best used in servers, where the configuration doesn't change much. See https://netplan.io/examples.

/etc/netplan .yaml example to enable NetworkManager...

---

network:
  version: 2
  renderer: NetworkManager

---

In terminal...

sudo netplan generate # generate config files

sudo netplan apply # apply the new config

reboot # reboot to confirm network operation

Solution 2

Another option is systemd-networkd.service, instead of NetworkManager.service.

Background story

I was having problems with NetworkManager when after changing network settings a couple of times the DNS would fail.

I noticed that systemd-resolved.service is supposed to work with both network-manager and systemd-network.

But systemd-networkd is actually part of the systemd family of software. So (I thought maybe) it will communicate better with systemd-networkd than NetworkManager. It tried it and it did seem better.

How to set up systemd-networkd

Set up /etc/systemd/network/10-enp2s0.network where enp2s0 is the name of your interface as seen with ifconfig. It might be eth0. Here is a simple example of DHCP with DNS override. Note the DNS= directive can be used multiple times.

[Match]
MACAddress=1c:dd:dd:dd:dd:dd

[Network]
DHCP=yes
DNS=208.67.222.222
DNS=208.67.220.220

The [Network] section for a fixed address.

[Network]
Address=192.168.1.172/24
Gateway=192.168.1.1
DNS=208.67.222.222
DNS=208.67.220.220

More examples

Test it out -

systemctl stop NetworkManager.service
systemctl start systemd-networkd.service
systemctl restart systemd-resolved.service

On my system with systemd-resolved running, the resolv.conf file is a link -

/etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

If the link is not replaced automatically during the restart, you might want to link it manually and restart systemd-resolved again.

If its working as hoped than set their boot time startup behaviour -

systemctl disable NetworkManager.service
systemctl enable systemd-networkd.service

Blame

There are always two sides to an interface.

Comments

[Boris Hamanov]

You first have to make a decision to use NetworkManager or netplan. If you connect wi-fi to various wireless networks, then NetworkManager is probably the better choice. Netplan is best used in servers, where the configuration doesn't change much. See netplan.io/examples.

[stackinator]

@heynnema is this NetworkManager? Or is it something else? Please see this image linuxconfig.org/images/…

[Boris Hamanov]

That's NetworkManager. netplan has no GUI... only files in /etc/netplan, and the netplan CLI. However, if you're using NetworkManager, there's still one relevant .yaml file in /etc/netplan.

[stackinator]

@heynnema and correct me if I'm wrong but I'll need to enable NetworkManager for 18.04 in my /etc/netplan file like this: network:\n [TAB]version: 2 [TAB]renderer: NetworkManager and then I run netplan generate && netplan apply.

[Boris Hamanov]

That's correct. Indentation is important. See my answer, below, or the examples site that I quoted earlier. Use spaces, not tabs.

[fkraiem]

Probably you meant "You first have to make a decision to use NetworkManager or systemd-networkd." The configuration in your answer is using netplan, with NetworkManager as the renderer (instead of systemd-networkd).

[Asfand Qazi]

THANK YOU. I used the mini ISO to install Ubuntu, and connected via WiFi during the install process. When I installed my GUI desktop I found that network manager didn't pick up my WiFi! (I use Ansible to provision my desktops to prefer to start with a blank slate, hence mini ISO). This helped me, thank you.

[Boris Hamanov]

@AsfandQazi Glad it was helpful for you.