1

After the latest Ubuntu update maybe due to pihole installed in my system, the server fails to resolve address. I completely uninstalled pihole but the issue persists. I saw that in the latest Ubuntu versions netplan is used so I tried to configure the yaml file like that 

network:
  version: 2
  renderer: networkd
  ethernets:
    eno1:
      addresses:
        - 192.168.5.20/32
      gateway4: 192.168.5.1
      nameservers:
          search: [local]
          addresses: [192.168.5.1]

I applied the configuration and in the system-resolve --status command, the proper configuration is applied. The dns server where is pointed is working as all of my devices/phones/nas/etc are working without an issue.

I tried edit after the /etc/systemd/resolved.conf but the issue persists. The only thing that temporary fixed the issue is modifying the /etc/resolved.conf still with the same dns server and there the addresses seems to resolve without problem. The problem is that in every restart the configuration is lost and is getting replaced by 127.0.0.1 and the system stops resolving addresses. Any help on how to completely maybe restore the network configuration without reinstalling everything?

After pkg -l dnsmasq i get : 

Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name             Version       Architecture Description
+++-================-=============-============-================================
un  dnsmasq          <none>        <none>       (no description available)
ii  dnsmasq-base     2.80-1ubuntu1 amd64        Small caching DNS proxy and DHCP
un  dnsmasq-base-lua <none>        <none>       (no description available)

After ls -al /etc/resolv.conf i get :

lrwxrwxrwx 1 root root 29 May  4 00:48 /etc/resolv.conf -> ../run/resolvconf/resolv.conf

After cat /etc/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.

nameserver 192.168.5.13
search local

After cat /etc/network/interfaces :

 ifupdown has been replaced by netplan(5) on this system.  See
# /etc/netplan for current configuration.
# To re-enable ifupdown on this system, you can run:
#    sudo apt install ifupdown

After cat /etc/systemd/resolved.conf:

#  This file is part of systemd.

...

[Resolve]
DNS=192.168.5.1
#FallbackDNS=
#Domains=
#LLMNR=no
#MulticastDNS=no
#DNSSEC=no
#DNSOverTLS=no
#Cache=yes
#DNSStubListener=yes
#ReadEtcHosts=yes

After the command system-resolve --status i get :

   Global
       LLMNR setting: no
MulticastDNS setting: no
  DNSOverTLS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
         DNS Servers: 192.168.5.1
          DNSSEC NTA: 10.in-addr.arpa
                      16.172.in-addr.arpa
                      168.192.in-addr.arpa
                      17.172.in-addr.arpa
                      18.172.in-addr.arpa
                      19.172.in-addr.arpa
                      20.172.in-addr.arpa
                      21.172.in-addr.arpa
                      22.172.in-addr.arpa
                      23.172.in-addr.arpa
                      24.172.in-addr.arpa
                      25.172.in-addr.arpa
                      26.172.in-addr.arpa
                      27.172.in-addr.arpa
                      28.172.in-addr.arpa
                      29.172.in-addr.arpa
                      30.172.in-addr.arpa
                      31.172.in-addr.arpa
                      corp
                      d.f.ip6.arpa
                      home

after cat /etc/NetworkManager/NetworkManager.conf :

there's a blank line only displayed.

after sudo systemctl status systemd-resolved i get :

Systemd-resolved.service - Network Name Resolution
   Loaded: loaded (/lib/systemd/system/systemd-resolved.service; enabled; ve
   Active: active (running) since Sun 2019-07-28 15:39:52 CEST; 4h 44min ago
     Docs: man:systemd-resolved.service(8)
           https://www.freedesktop.org/wiki/Software/systemd/resolved
           https://www.freedesktop.org/wiki/Software/systemd/writing-network
           https://www.freedesktop.org/wiki/Software/systemd/writing-resolve
 Main PID: 3349 (systemd-resolve)
   Status: "Processing requests..."
    Tasks: 1 (limit: 4915)
   Memory: 2.4M
   CGroup: /system.slice/systemd-resolved.service
           └─3349 /lib/systemd/systemd-resolved

Jul 28 15:39:51 plex systemd[1]: Starting Network Name Resolution...
Jul 28 15:39:52 plex systemd-resolved[3349]: Positive Trust Anchors:
Jul 28 15:39:52 plex systemd-resolved[3349]: . IN DS 19036 8 2 49aac11d7b6f6
Jul 28 15:39:52 plex systemd-resolved[3349]: . IN DS 20326 8 2 e06d44b80b8f1
Jul 28 15:39:52 plex systemd-resolved[3349]: Negative trust anchors: 10.in-a
Jul 28 15:39:52 plex systemd-resolved[3349]: Using system hostname 'plex'.
Jul 28 15:39:52 plex systemd[1]: Started Network Name Resolution.

and yes after reboot it changes to 127.0.0.1

cat /run/systemd/resolve/resolv.conf gives me :

# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known uplink DNS servers. This file lists all configured search domains.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 192.168.5.1
search local

and

cat /run/systemd/resolve/stub-resolv.conf gives me :

# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "resolvectl status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 127.0.0.53
options edns0
search local

sudo lshw -C network gives me :



  *-network                 
       description: Wireless interface
       product: Wireless 8265 / 8275
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:3a:00.0
       logical name: wlp58s0
       version: 78
       serial: f8:63:3f:08:69:43
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
       configuration: broadcast=yes driver=iwlwifi driverversion=5.0.0-20-generic firmware=36.9f0a2d68.0 latency=0 link=no multicast=yes wireless=IEEE 802.11
       resources: irq:129 memory:dc100000-dc101fff
  *-network
       description: Ethernet interface
       product: Ethernet Connection (4) I219-V
       vendor: Intel Corporation
       physical id: 1f.6
       bus info: pci@0000:00:1f.6
       logical name: eno1
       version: 21
       serial: f4:4d:30:6a:0d:e7
       size: 1Gbit/s
       capacity: 1Gbit/s
       width: 32 bits
       clock: 33MHz
       capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=3.2.6-k duplex=full firmware=0.1-4 ip=192.168.5.20 latency=0 link=yes multicast=yes port=twisted pair speed=1Gbit/s
       resources: irq:125 memory:dc280000-dc29ffff
  *-network:0
       description: Ethernet interface
       physical id: 2
       logical name: br-c20159f39807
       serial: 02:42:82:dc:5c:c1
       capabilities: ethernet physical
       configuration: broadcast=yes driver=bridge driverversion=2.3 firmware=N/A ip=172.18.0.1 link=yes multicast=yes
  *-network:1
       description: Ethernet interface
       physical id: 3
       logical name: veth3e14a42
       serial: 4e:59:53:86:1b:a8
       size: 10Gbit/s
       capabilities: ethernet physical
       configuration: autonegotiation=off broadcast=yes driver=veth driverversion=1.0 duplex=full ip=169.254.130.45 link=yes multicast=yes port=twisted pair speed=10Gbit/s
  *-network:2
       description: Ethernet interface
       physical id: 4
       logical name: vethb1a5fa9
       serial: ea:45:16:b6:ee:13
       size: 10Gbit/s
       capabilities: ethernet physical
       configuration: autonegotiation=off broadcast=yes driver=veth driverversion=1.0 duplex=full ip=169.254.6.237 link=yes multicast=yes port=twisted pair speed=10Gbit/s
  *-network:3
       description: Ethernet interface
       physical id: 5
       logical name: docker0
       serial: 02:42:18:4e:ed:2f
       capabilities: ethernet physical
       configuration: broadcast=yes driver=bridge driverversion=2.3 firmware=N/A ip=172.17.0.1 link=no multicast=yes
  *-network:4
       description: Ethernet interface
       physical id: 6
       logical name: veth1f469d7
       serial: 46:51:7b:28:7a:11
       size: 10Gbit/s
       capabilities: ethernet physical
       configuration: autonegotiation=off broadcast=yes driver=veth driverversion=1.0 duplex=full ip=169.254.74.93 link=yes multicast=yes port=twisted pair speed=10Gbit/s
  *-network:5
       description: Ethernet interface
       physical id: 7
       logical name: vethcd445dd
       serial: 26:6e:38:e2:da:1f
       size: 10Gbit/s
       capabilities: ethernet physical
       configuration: autonegotiation=off broadcast=yes driver=veth driverversion=1.0 duplex=full ip=169.254.168.110 link=yes multicast=yes port=twisted pair speed=10Gbit/s
  *-network:6
       description: Ethernet interface
       physical id: 8
       logical name: veth9810524
       serial: ee:a9:1f:d7:e3:b7
       size: 10Gbit/s
       capabilities: ethernet physical
       configuration: autonegotiation=off broadcast=yes driver=veth driverversion=1.0 duplex=full ip=169.254.61.7 link=yes multicast=yes port=twisted pair speed=10Gbit/s
  *-network:7
       description: Ethernet interface
       physical id: 9
       logical name: veth538f6bc
       serial: 5e:b5:25:5c:b9:5d
       size: 10Gbit/s
       capabilities: ethernet physical
       configuration: autonegotiation=off broadcast=yes driver=veth driverversion=1.0 duplex=full ip=169.254.52.246 link=yes multicast=yes port=twisted pair speed=10Gbit/s
  *-network:8
       description: Ethernet interface
       physical id: a
       logical name: br-03e193556b79
       serial: 02:42:77:59:85:26
       capabilities: ethernet physical
       configuration: broadcast=yes driver=bridge driverversion=2.3 firmware=N/A ip=172.20.0.1 link=yes multicast=yes
  *-network:9
       description: Ethernet interface
       physical id: b
       logical name: vethb3f499f
       serial: 6a:be:8c:01:13:ec
       size: 10Gbit/s
       capabilities: ethernet physical
       configuration: autonegotiation=off broadcast=yes driver=veth driverversion=1.0 duplex=full ip=169.254.196.173 link=yes multicast=yes port=twisted pair speed=10Gbit/s
  *-network:10
       description: Ethernet interface
       physical id: c
       logical name: vethb56cefe
       serial: 6a:74:3a:90:6b:60
       size: 10Gbit/s
       capabilities: ethernet physical
       configuration: autonegotiation=off broadcast=yes driver=veth driverversion=1.0 duplex=full ip=169.254.82.220 link=yes multicast=yes port=twisted pair speed=10Gbit/s
Improve this question
9
  • pihole tends to make a real mess of things. It may require a Ubuntu Server reinstall... but lets check a few things first... edit your question and show me dpkg -l *dnsmasq* and ls -al /etc/resolv.conf and cat /etc/resolv.conf and cat /etc/network/interfaces and cat /etc/systemd/resolved.conf and system-resolve --status and lastly cat /etc/NetworkManager/NetworkManager.conf. I know that's a lot of stuff...
    – heynnema
    Jul 28, 2019 at 15:33
  • 2
    Any particular reason for 192.168.5.20/32 instead of 192.168.5.20/24?
    – heynnema
    Jul 28, 2019 at 15:35
  • not at all thanx for helping. i would prefer not reinstalling as it's too much to reconfigure all the plex staff /all the docker containers/services, i would definitely keep it like that until i have my next big vacation from work..i have the pihole in the raspberry meanwhile xD The reason of the specific ip was that i have configured everything that the server needs (nfs shares,etc) with the 20 ip even if the unifi should give it a static one.
    – sessho
    Jul 28, 2019 at 18:07
  • Sorry... the correct command is systemd-resolve --status. Is your /etc/resolv.conf after a manual edit? If so, what does it show after a reboot... 127.0.0.1 or 127.0.0.53? What about sudo systemctl status systemd-resolved? Be sure to start comments to me with @heynnema, or I'll surely miss them.
    – heynnema
    Jul 28, 2019 at 18:19
  • @heynnema yes otherwise the adress resolution doesnt work.After i reboot the file get back 127.0.0.1.
    – sessho
    Jul 28, 2019 at 18:27

1 Answer 1

Reset to default
1

From the comments...

After the installation, and removal, of pihole, DNS didn't work any more. We changed the symlink that was using /run/resolvconf/resolv.conf for /etc/resolv.conf, via the following...

sudo rm -i /etc/resolv.conf

sudo ln -s /run/systemd/resolve/stub-resolv.conf /etc/resolv.conf

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.