Please follow the below template, it will help us to help you!
If you are Experiencing issues with a Pi-hole install that has non-standard elements (e.g you are using nginx instead of lighttpd, or there is some other aspect of your install that is customised) - please use the Community Help category.
Expected Behaviour:
I bought a fresh Odroid which is running Ubuntu-Mate where Ubuntu is at 20.04.1 LTS. The first time, I used the Mate GUI to set a static IP. Then I unhooked the monitor and did everything via ssh.
I did the curl | bash as recommended. Bad me... I wasn't paying attention. I've used Pi-Hole before on a older Odroid and just assumed everything went ok. But eventually I figured out that it wasn't working.
So, via ssh, I tried to figure out what was wrong but eventually just uninstalled pihole (via "pihole uninstall" -- I did it twice) and then hooked up the monitor and set the network back to DHCP.
The second time I just left it as DHCP and the IP address wasn't fixed anywhere but I was going to do that after the pi-hole seemed to be working. I did the same "curl ... | bash" as before and this time noticed the last two lines:
[✗] DNS resolution is currently unavailable
[✗] DNS resolution is not available
I believe this happened the first time, I just didn't pay attention to it...
Now, no name resolution is working at all. e.g.
ping ubuntu.com
ping: ubuntu.com: Temporary failure in name resolution
nslookup pi.hole
;; connection timed out; no servers could be reached
I need to install pihole again to see what state it is in when I'm done but I finally figured out that systemd-resolved listens on 127.0.0.53:53 and the local dig on the pihole itself is likely using that path. The log says that pihole-FTL is listening on 127.0.0.1:53 so removing the DNSStubListener and not updating /etc/resolv.conf which still points to 127.0.0.53:53 I believe is the problem.
BUT... I am sure you guys know TONS more than I do so I'm assuming that something is suppose to be happening that isn't and it might be due to how I've modified things in the past.
I'm going to wait to morning and start fresh. I plan to assign a fixed IP and then install pihole and see where things stand at that point: i.e. see what /etc/resolf.conf has in it and see which ports are being listened to, etc.
Yes, your Ubuntu host machine indeed is (or has been) using systemd-resolved for its own DNS calls.
In general, it's a good idea to have Pi-hole's host use another DNS server instead of or in addition to Pi-hole, as that would allow you to receive OS updates and run Pi-hole's repair or update scripts in the event of Pi-hole's DNS failing for some reason.
However, another local resolver is likely to introduce port conflicts.
While it may be possible to resolve those by individual manual configuration, I'd consider disabling the stub resolver as the better choice.
If you don't want to forego DNS caching, you could configure your host to use Pi-hole for DNS.
The exact steps required to disable the local stub-resolver and to configure the host system's DNS resolution would depend on your OS and its version.
A cursory search turned up dns - How to disable systemd-resolved in Ubuntu? - Ask Ubuntu, where the top answer currently claims to be applicable to Ubuntu 20.04.
You should also consider consulting your OS's support channels for further details.
I plan to install unbound. The set up I had before was pi-hole with unbound (because of suggestions made here). This time, because my router is braindead, it appears I need the same pihole with unbound but also enable pihole's DHCP server.
So, this appears to be working 100%. The system says it is Ubuntu 20.04.4 LTS. I has the Mate GUI on top which may or may not affect things. @Bucking_Horn pointer to this reply tells how to get systemd-resolved out of the loop. I think one key thing is to remove the symlink so NetworkManager writes a valid /etc/resolv.conf
I set my router to give my pi-hole the same IPv4 address (question about this later).
I then installed pi-hole using the recommended curl ... | bash command and it all went well.
I then used this page to install and set up unbound.
It all went like clockwork once systems-resolved was out of the picture.
The DHCP server is on the router. The DNS it gives out is for the router but it is forwarding it to the pi-hole. Originally, it would not accept that address but I think I know why. In any case, I got it to accept the address finally.
My last question: The router has an entry for a DNS for IPv6 and so I put the global unique IPv6 address in for the pi-hole. I tried putting in the IPv6 address that comes from the MAC address but it wouldn't take it. My question is, is this address stable? There isn't a facility like there is with the IPv4 DHCP to pre-allocate hostnames and IP addresses based on MAC addresses with this router. And it appears the IPv6 prefix is given to the router as well. What are the recommendations for this?