I am running a local server using Ubuntu 20.04, and had a need to do one thing that should be simple - tell it to resolve DNS using something other than the ISP's DNS server. However for reasons I won't go into it does need to get its IP address using DHCP, so no static IP address. This was easy to implement in previous versions of Ubuntu, and apparently is still not too difficult if you are running a desktop, but I've yet to see good clear instructions on how to do it in Ubuntu Server.
What I tried and what appears to work for now, is this:
sudo apt update sudo apt install resolvconf sudo nano /etc/resolv.conf
(Right under the commented out lines I added two nameserver lines pointing to the Preferred DNS, for example
nameserver 220.127.116.11 nameserver 18.104.22.168
then saved and exited nano)
sudo systemctl start resolvconf.service
Now that appears to have worked but what troubles me is this text that appears in resolv.conf:
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN # 127.0.0.53 is the systemd-resolved stub resolver. # run "systemd-resolve --status" to see details about the actual nameservers.
Despite this I see that a lot of people tell you to go ahead and edit this file anyway, but what I am wondering is, is this file going to get overwritten at some point, and if so, then what is now considered the "correct" way to specify nameservers in Ubuntu 20.04, keeping in mind that I can't use a static IP address and that I don't have a desktop on the system? You would think by now someone would have covered this in a web page or video, but if so I can't find it.
EDIT: I do realize that the "correct" way should involve modifying the /etc/netplan/00-installer-config.yaml file to use specific nameservers, but the problem with that is that if you do not set dhcp4: to false or no, it adds the DNS servers you specify to the list that already includes the one(s) it got from DHCP. So if the DHCP request specifies using the ISP's nameserver, it will always check that first, and only go to your preferred nameservers if that DNS fails to respond. Obviously that's not the desired behavior, and that's exactly what prompted me to install resolvconf in the first place.
But continuing on this theme, what I'd really kind of like to implement, if it's not too terribly difficult, is DNS encryption, which I guess is called DNS over TLS. What I am wanting to know is if this capability is built into Ubuntu Server and if so, how you enable it. I have seen several pages that suggest installing a package called stubby, but once again pretty much all the instructions I find are written for users of earlier Ubuntu versions or for Ubuntu desktop users.
This all seems like it would have been a lot easier in Ubuntu 18.04, but in all the pages I have visited trying to get solid information on this subject, if 20.04 is mentioned at all the instructions almost universally tell you to use the network configuration tool in the desktop version. It's as if no one seems to know the correct way to do something that should be really easy in Ubuntu 20.04 without using that GUI-based utility. So I'm wondering why they made this harder for users - that kind of seems like going in the wrong direction!