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I'm currently working on a project with Ubuntu Core with a RPi3. We are planning on installing the device on-site for experimental purposes, using the Wi-Fi interface for communication to the internet, on networks that use security PEAP+MSCHAPV2 authentification. To achieve connecting to this network, I've used Network Manager, mostly with success (it is connected, gets an address, receives DNS servers, etc.).

For developpement purposes, it was connected to my laptop, through ethernet, where I was sharing the internet (for initial updates, installing Network Manager, setting up the wireless network). To do so, I had configured the eth0 device to use a static config, setting my laptops IP address as the gateway and adding specific dns addresses.

As I approached my goal, I removed the gateway address and DNS settings from the ethernet to let the Pi talk to the internet through wi-fi. This failed with a nice "temporary failure in name resolution". A direct ping to the dns server addresses works, but with the domain name, it doesn't.

After tinkering, I added the DNS addresses back to the ethernet configuration through console-conf, and weirdly enough, wifi would work. I've checked out wireshark from my laptop to confirm the ping wasn't coming through it and no trace of it.

It seems like DNS through Network Manager is broken, and that it will fallback to the ones configured for another interface to work. This seems wrong.

Anyone encounter anything similar? Is there a way to manage this properly ?

TL;DR : Network Manager configured WiFi with specific set DNS address fails to resolve names, unless the ethernet configuration in console-conf sets the proper DNS address.

Edit 21/03/2019: Output from ls -al /etc/resolv.conf: lrwxrwxrwx 1 root root 39 Mar 12 20:44 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

Sorry for bad formatting, responded from my phone

  • Please edit your question to add the result of the terminal command: ls -al /etc/resolv.conf Welcome to Ask Ubuntu. – chili555 Mar 20 at 20:29
  • Did you set the DNS nameservers in Network Manager specifically for wifi? i.stack.imgur.com/Cumpo.png – chili555 Mar 21 at 15:43
  • As this is Ubuntu Core, I have no UI for this. I did use nmcli to set the DNS on wifi connection in the ipv4.dns section. – Jean-Philippe Fournier Mar 21 at 16:41
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I still shut off Network Manager and just use /etc/network/interfaces files. You can set your DNS there and resolv.conf should pick them up.

 dns-nameservers 192.168.1.1 8.8.8.8 208.67.220.220 

Simply restarting networking doesn't always work right, so either a reboot or a

ifdown eth0 && ifup eth0

...usually does the trick.

  • Since I'm running on Ubuntu Core, my system is read-only, including the interfaces file. Network Manager is the way of doing things on Core as per their documentation – Jean-Philippe Fournier Mar 21 at 16:45

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