DNS not resolving

b23

Getting the error "Temporary failure in name resolution" as the correct DNS entries are not getting picked up.
Ran ping with an IP address - worked, then nslookup and identified the DNS server involved.

$ ping -c 5 1.1.1.1
PING 1.1.1.1 (1.1.1.1) 56(84) bytes of data.
64 bytes from 1.1.1.1: icmp_seq=1 ttl=59 time=1.74 ms
. . .
--- 1.1.1.1 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4008ms
rtt min/avg/max/mdev = 1.588/1.762/1.926/0.108 ms

$ nslookup  203.12.160.36  8.8.8.8
36.160.12.203.in-addr.arpa	name = dns2.tpgi.com.au.

Running ping with URL gave the error:

$ ping google.com
ping: google.com: Temporary failure in name resolution

Flushed the DNS cache:

$ resolvectl flush-caches
$ resolvectl statistics

DNSSEC supported by current servers: no

Transactions             
Current Transactions:   0
  Total Transactions: 380
                         
Cache                    
  Current Cache Size:   0
          Cache Hits:   0
        Cache Misses: 938

Host command gave this output:

$ host -a apple.com
Trying "apple.com"
Host apple.com not found: 2(SERVFAIL)
Received 27 bytes from 127.0.0.53#53 in 0 ms

$ cat /etc/resolv.conf
..
nameserver 127.0.0.53
options edns0 trust-ad
search .

There were no other entries on the nameserver line. System settings in Budgie for both wired and wireless connections show 'Automatic' for DNS and the correct DNS server addresses from the router are displayed.

Any idea how to resolve this? It occurred after the most recent upgrades. Can these updates be backed out? Currently on Solus 4.5 6.8.10-291.current.

You might need to spell out any response - I'm neither a linux nor a networking person! Thx.

ReillyBrogan

What does resolvectl statistics say if you run it without flushing the cache after the DNS failure?

b23

Revised DNS server settings in the router and rebooted (router and linux). Revised DNS values retrieved and shown in Control Center Settings (Details tab) for connections.

With wi-fi connection, no ethernet, after a few pings with addresses (8.8.8.8...) and URLs which gave the error:

$ resolvectl statistics
DNSSEC supported by current servers: no

Transactions              
Current Transactions:    0
  Total Transactions:  580
                          
Cache                     
  Current Cache Size:    0
          Cache Hits:    0
        Cache Misses: 1441
                          
DNSSEC Verdicts           
              Secure:    0
            Insecure:    0
               Bogus:    0
       Indeterminate:    0

then through ethernet connection, no wireless, after a few more pings with addresses (8.8.8.8...) and URLs which give the error:

$ resolvectl statistics
DNSSEC supported by current servers: no

Transactions              
Current Transactions:    0
  Total Transactions:  804
                          
Cache                     
  Current Cache Size:    0
          Cache Hits:    0
        Cache Misses: 2001
                          
DNSSEC Verdicts           
              Secure:    0
            Insecure:    0
               Bogus:    0
       Indeterminate:    0

b23

Anyone got any thoughts on this?

Without DNS resolution, I am unable to access anything via the internet or update software (I assume - can I from the OS prompt?) So at present I have a totally stuck, and virtually useless, Solus box!

Any assistance would be much appreciated.

silke

b23 Can you give the output of the following commands?

resolvectl status
resolvectl query google.com
host google.com <dns server> where <dns server> is the 'Current DNS server' from the first command.

By the way, you can format the code blocks correctly using triple backticks (```) followed by a newline and ending it with a newline and triple backticks again.

b23

$ resolvectl status
Global
           Protocols: LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
    resolv.conf mode: stub
         DNS Servers: ::1
Fallback DNS Servers: 1.1.1.1#cloudflare-dns.com 8.8.8.8#dns.google
                      1.0.0.1#cloudflare-dns.com 8.8.4.4#dns.google
                      2606:4700:4700::1111#cloudflare-dns.com
                      2001:4860:4860::8888#dns.google
                      2606:4700:4700::1001#cloudflare-dns.com
                      2001:4860:4860::8844#dns.google

Link 2 (enp2s0)
    Current Scopes: LLMNR/IPv4 LLMNR/IPv6
         Protocols: -DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS
                    DNSSEC=no/unsupported

Link 3 (wlp3s0)
    Current Scopes: none
         Protocols: -DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS
                    DNSSEC=no/unsupported

Link 4 (ipv6leakintrf0)
    Current Scopes: DNS
         Protocols: +DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS
                    DNSSEC=no/unsupported
Current DNS Server: ::1
       DNS Servers: ::1
        DNS Domain: ~.

$ resolvectl query google.com
google.com: resolve call failed: Lookup failed due to system error: Connection refused

$ host google.com ::1
;; communications error to ::1#53: connection refused
;; communications error to ::1#53: connection refused
;; no servers could be reached

Code block looks a lot better this time - thanks. The value for Current DNS Server should be 203.12.160.35.

ReillyBrogan

systemd-resolved just takes whatever DNS server it receives from NetworkManager and uses that. What is the output of the following command?

nmcli dev show

If you don't see your DNS server there then I would recommend checking the network manager logs to see if anything useful is there

sudo journalctl -b0 -u NetworkManager.service

ReillyBrogan

If you are sure that 203.12.160.35 should be your DNS server then you can probably force it to work temporarily by opening /etc/systemd/resolved.conf (create it if it doesn't exist) and changing/adding the following:

[Resolve]
DNS=203.12.160.35

Then restart systemd-resolved with sudo systemctl restart systemd-resolved and see if it's working. You should be able to update then. Once fully updated try reverting those config changes and see if things keep working (since there have been a bunch of updates since you last updated, one of them might be the fix).

silke

Additionally, this looks suspicious:

Link 4 (ipv6leakintrf0)
    Current Scopes: DNS
         Protocols: +DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS
                    DNSSEC=no/unsupported
Current DNS Server: ::1
       DNS Servers: ::1
        DNS Domain: ~.

Something (probably ProtonVPN) has configured ::1 (your machine) as a server for ~. (every domain). Deleting it using nmcli connection delete pvpn-ipv6leak-protection should allow systemd-resolved to use the fallback options configured.

b23

nmcli dev show produced output below and the IP4.DNS entries from the router are shown (and used by other PCs connected to the router).

GENERAL.DEVICE:                         enp2s0
GENERAL.TYPE:                           ethernet
GENERAL.HWADDR:                         A8:A1:59:6C:E2:22
GENERAL.MTU:                            1500
GENERAL.STATE:                          100 (connected)
GENERAL.CONNECTION:                     Wired connection 1
GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/ActiveConnection/3
WIRED-PROPERTIES.CARRIER:               on
IP4.ADDRESS[1]:                         172.23.1.11/24
IP4.GATEWAY:                            172.23.1.1
IP4.ROUTE[1]:                           dst = 172.23.1.0/24, nh = 0.0.0.0, mt = 100
IP4.ROUTE[2]:                           dst = 0.0.0.0/0, nh = 172.23.1.1, mt = 100
IP4.DNS[1]:                             203.12.160.35
IP4.DNS[2]:                             1.1.1.1
IP6.ADDRESS[1]:                         fe80::9153:b441:289f:705f/64
IP6.GATEWAY:                            --
IP6.ROUTE[1]:                           dst = fe80::/64, nh = ::, mt = 1024

In /etc/ I have the line in the file listing:

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

and the file contains (apart from comments):

nameserver 127.0.0.53
options edns0 trust-ad
search .

also the file /run/systemd/resolve/resolv.conf that contains:

nameserver ::1
search .

but nothing relating to /etc/systemd or contained in the /etc/systemd directory.
Created resolved.conf and restarted it as above but without any success.

$ ping -c9 google.com
ping: google.com: Temporary failure in name resolution

although ping -c5 8.8.8.8 still works fine.

I did have ProtonVPN installed until very recently - removed it to try and cut out possibilities - but the actual uninstall made no difference. Ran command below and .... success!!

$ nmcli connection delete pvpn-ipv6leak-protection
Connection 'pvpn-ipv6leak-protection' (6d6c4e02-028b-44ee-a7dc-e934552f06d9) successfully deleted.

$ ping -c9 google.com
PING google.com (142.250.70.206) 56(84) bytes of data.
64 bytes from mel05s01-in-f14.1e100.net (142.250.70.206): icmp_seq=1 ttl=56 time=18.2 ms
64 bytes from mel05s01-in-f14.1e100.net (142.250.70.206): icmp_seq=2 ttl=56 time=18.7 ms

All seems to be working fine now, including updates (a few hundred).

Thanks for your help on this - it's something I couldn't have worked out!

A couple of follow-up questions:

Should resolved.conf be removed now from /etc/systemd/?
Is it a good move to be using ProtonVPN if it causes these issues?

silke

b23 Good to hear that helped!

The symlinks/contents in /etc/resolv.conf and /run/systemd/resolve/resolv.conf are correct.

Should resolved.conf be removed now from /etc/systemd/?

Depends on what resolvectl status shows: it should show 203.12.160.35 and 1.1.1.1 for enp2s0. If that isn't the case something is still somewhat wrong somewhere.

Is it a good move to be using ProtonVPN if it causes these issues?

This is caused by a feature from ProtonVPN that ensures that no information leaks outside of the VPN. So it's actually a good thing unless you want to use the internet without a VPN.

b23

Re-installed ProtonVPN and seems to be working OK. Output below shows DNS entries after the install

$ resolvectl status
Global
           Protocols: LLMNR=resolve -mDNS -DNSOverTLS DNSSEC=no/unsupported
    resolv.conf mode: stub
  Current DNS Server: 203.12.160.35
         DNS Servers: 203.12.160.35
Fallback DNS Servers: 1.1.1.1#cloudflare-dns.com 8.8.8.8#dns.google
                      1.0.0.1#cloudflare-dns.com 8.8.4.4#dns.google
                      2606:4700:4700::1111#cloudflare-dns.com
                      2001:4860:4860::8888#dns.google
                      2606:4700:4700::1001#cloudflare-dns.com
                      2001:4860:4860::8844#dns.google

Link 2 (enp2s0)
    Current Scopes: DNS LLMNR/IPv4 LLMNR/IPv6
         Protocols: +DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS
                    DNSSEC=no/unsupported
Current DNS Server: 1.1.1.1
       DNS Servers: 203.12.160.35 1.1.1.1

Link 3 (wlp3s0)
    Current Scopes: none
         Protocols: -DefaultRoute LLMNR=resolve -mDNS -DNSOverTLS
                    DNSSEC=no/unsupported

When running (almost all the time), ProtonVPN seems to consume increasing amounts of RAM. Not sure if this is related to the information held or not (memory leak?) but I have needed to shut it down and restart it on occasions.

silke

b23 That looks correct! Feel free to remove /etc/systemd/resolved.conf.

When running (almost all the time), ProtonVPN seems to consume increasing amounts of RAM. Not sure if this is related to the information held or not (memory leak?) but I have needed to shut it down and restart it on occasions.

Yeah, that sounds like a memory leak. I wouldn't expect it to be related unless it actually crashes because of it.

b23

Will followup with Proton as RAM use has gone from around 10% to more than 50% during a day without any use of the PC!

Thanks for the help. Will close ticket.