Ubuntu 18.04: changing network configuration

With the release of Ubuntu 18.04 Bionic Beaver administrators need to learn new tools for network management, namely iproute and netplan.

iproute has been around for quite a while, so it’s not that new. It’s a replacement of ifconfig and it’s very easy and comfortable once you learn the syntax.

netplan instead is pretty new to me, I never heard about it before. I got to know about it thanks to an excellent What’s new page on DigitalOcean, and I found out my good ol’ /etc/network/interfaces has gone. So what’s now? a YAML configuration file! I’ve never been fond of yaml, but I also admit  I never used it consistently, so let’s give it a hope.

Luckily I recently had to install a new VPS, and luckily again our currently favourite hosting provider, the incomparably cheap Contabo, already has Ubuntu 18.04 as available operating system! I couldn’t miss the chance!

After installing I wanted to change system’s DNS servers, as in the past I’ve had problems with Contabo’s ones. So I opened the shiny new /etc/netplan/01-netcfg.yaml and added my DNSes. Yaml is very intuitive to read, tough I’m still a little bit new on how to add stuff… The final result:

network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
      match:
        macaddress: 00:x:x:x:x:3d
      addresses:
        - 173.x.x.x/24
        - 2a02:x:x:x:x:x:x:0001/64
      gateway4: 173.x.x.x
      gateway6: fe80::1
      nameservers:
        search: [ invalid ]
        addresses:
          - 1.1.1.1
          - 37.235.1.177
          - 2606:4700:4700::1001
          - 2001:4860:4860::8844

I’m using a mix of Cloudflare’s 1.1.1.1, FreeDNS.zone and Google DNS.

So now, how to update the system configuration? Restarting systemd-networkd.service didn’t help, so what?

The solution is to use netplan command!

Just running netplan apply will  apply changes made to 01-netcfg.yaml! That’s it!

If you’re uncertain about what you did you can also run netplan try which will apply the configuration and roll it back in 120s if you don’t confirm it with a keypress! Super cool!

 

root@linux-host:~# netplan try
Do you want to keep these settings?

Press ENTER before the timeout to accept the new configuration

Changes will revert in 113 seconds

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