• DNS resolution stopping on 6.12.0-rc5 and rc6

    Kaldek

    By Kaldek

      • Annoyance

    This issue appears to be occurring every few days.  I can't ping any hostnames from the CLI, and /etc/resolv.conf is blank.  I do not use DHCP for the server address, and my DNS servers are statically assigned.

     

    In addition, when it happens I am unable to reboot the server as the shares will never unmount as it constantly tells me /mnt/cache is busy.  There are definitely no clients holding shares open when this happens.

     

    I have attached diagnostics of when the server is working, and will attach again when it next fails.  I have made one change today after the last failure, and that was to disable IPv6.  My dual stack ISP connection isn't always the best when it comes to IPv6 working all the time, so I've disabled IPv6 to see if that helps, since this seems to mainly be a network issue.

     

    unraid-diagnostics-20230521-1953.zip

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    LMD
    12 hours ago, witalit said:

     

    Did you check the setting is enabled I mentioned above? 

     

    Forgot to post it that I did check this setting, thanks for reminding me on this, but it has been off all the time. Using VLAN's for my dockers, so they all work fine.

    image.png.ad8cf6734867dfe9b11e36683df363da.png

     

    1 VM is still running and working fine, but when I would like to start one, I get an error, which seems to need DNS settings as well.

    image.png.c47f4310ff8690e09424bd23b95459ba.png

     

     

    Did try the following, but without a result. 

    ifconfig br0 down && ifconfig br0 up

     

    Hopefully there is a solution in the long term for this, due it is annoying to reboot the server to have it working a gain, but no clue for how long it will work then.

    Link to comment
    LMD

    It has something todo with Docker. I did reboot server 3 days ago and it was working. Now 3 days and 1 hour DNS gone.

    Before I decided to do things I checked some settings in interface:

    Settings -> Network Settings

    IPv4 DNS server: Empty (no value)

     

    Shutting down all dockers that where active.

    Settings -> Network Settings

    IPv4 DNS server: IP adress of correct DNS server

     

    The dockers that where active(including the Repository):

    Unifi-controller -> linuxserver/unifi-controller:latest

    Influxdb -> influxdb:1.8.4-alpine

    HDDTemp -> drewster727/hddtemp-docker

    telegraf -> telegraf:1.20.2-alpine

    apcupsd-influcdb-exporter -> atribe/apcupsd-influxdb-exporter

    tautulli -> tautulli/tautulli

    Unifi-Poller -> golift/unifi-poller

    CrashPlanPro -> jlesage/crashplan-pro

    Duplicacy -> saspus/duplicacy-web

    letsencrypt -> linuxserver/swag

    sabnzbd -> linuxserver/sabnzbd

    radarr -> linuxserver/radarr

    sonarr -> linuxserver/sonarr

    bazarr -> linuxserver/bazarr

    Varken -> boerderij/varken

    Plex -> plexinc/pms-docker

    jellyfin -> lscr.io/linuxserver/jellyfin:latest

    tdarr -> ghcr.io/haveagitgat/tdarr

    tdarr_node -> ghcr.io/haveagitgat/tdarr_node

    DiskSpeed -> jbartlett777/diskspeed

    Satisfactory -> ich777/steamcmd:satisfactory

    Dozzle -> amir20/dozzle

     

    Added the Diagnostics.

     

    mindfix4-diagnostics-20230608-1408.zip

    Link to comment
    Thx And Bye
    10 hours ago, nblom said:

    Are you using Plex with NVIDIA drivers?

     

    Yes I have Nvidia Driver version 535.54.03 and the latest plexinc/pms-docker installed.

    Edited by Thx And Bye
    Link to comment
    mrcake

    I had a similar issue on 16.12.2

    primary dns was set to the ip of a docker container (pihole)

    secondary was 1.1.1.1

    Host access to custom networks: Disabled

     

    after some time (+- 12h) dns resolution stopped working

    If I did nslookup and specified the dns server manually it worked (both primary and secondary)

     

    I currently just use 1.1.1.1 as primary dns and I have not had any issues yet.

     

    Edited by mrcake
    Link to comment
    lucahammer

    I am running Version 6.12.3 and may have a related issue. I am using IPv4+IPv6 with DHCP. The nameserver entry for IPv6 has '%br0' at the end which can't be parsed by avahi-demon and is then ignored. I only noticed it because smokeping keeps throwing errors because of it: 

    ERROR: output of '/usr/bin/dig localhost' does not match (?^i:query time:\s+([0-9.]+)\smsec.*)
 at (eval 105) line 1.

ERROR: output of '/usr/bin/dig localhost' does not match (?^i:query time:\s+([0-9.]+)\smsec.*)
 at (eval 103) line 1.

     

    Content of resolv.conf 

    # Generated by dhcpcd from br0.dhcp, br0.ra
domain localdomain
nameserver 192.168.178.2
nameserver fe80::1ae8:29ff:fe42:1f04%br0

     

    When I manually edit resolv.conf (on Unraid or the smokeping container) it starts working. But after some time it's updated again. As it should. But without '%br0' at the end.

     

    Not sure if it's related, but avahi-daemon is started and restarted within a few seconds during startup. syslog: 

    Aug 17 10:28:22 MeshifyUnraid emhttpd: shcmd (21): /etc/rc.d/rc.avahidaemon start
Aug 17 10:28:22 MeshifyUnraid root: Starting Avahi mDNS/DNS-SD Daemon: /usr/sbin/avahi-daemon -D
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Found user 'avahi' (UID 61) and group 'avahi' (GID 214).
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Successfully dropped root privileges.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: avahi-daemon 0.8 starting up.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Successfully called chroot().
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Successfully dropped remaining capabilities.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Loading service file /services/sftp-ssh.service.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Loading service file /services/smb.service.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Loading service file /services/ssh.service.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Joining mDNS multicast group on interface br0.IPv6 with address 2a00:6020:12b2:4567:89ca:80ff:fe78:ae7a.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: New relevant interface br0.IPv6 for mDNS.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Joining mDNS multicast group on interface br0.IPv4 with address 192.168.178.145.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: New relevant interface br0.IPv4 for mDNS.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Network interface enumeration completed.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Registering new address record for 2a00:6020:12b2:4567:89ca:80ff:fe78:ae7a on br0.*.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Registering new address record for 192.168.178.145 on br0.IPv4.
Aug 17 10:28:22 MeshifyUnraid avahi-daemon[4102]: Failed to parse address 'fe80::1ae8:29ff:fe42:1f04%br0', ignoring.
Aug 17 10:28:22 MeshifyUnraid emhttpd: shcmd (22): /etc/rc.d/rc.avahidnsconfd start
Aug 17 10:28:22 MeshifyUnraid root: Starting Avahi mDNS/DNS-SD DNS Server Configuration Daemon:  /usr/sbin/avahi-dnsconfd -D
Aug 17 10:28:22 MeshifyUnraid avahi-dnsconfd[4116]: Successfully connected to Avahi daemon.
...
Aug 17 10:28:38 MeshifyUnraid emhttpd: shcmd (65): /etc/rc.d/rc.avahidaemon restart
Aug 17 10:28:38 MeshifyUnraid root: Stopping Avahi mDNS/DNS-SD Daemon: stopped
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[4102]: Got SIGTERM, quitting.
Aug 17 10:28:38 MeshifyUnraid avahi-dnsconfd[4116]: read(): EOF
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[4102]: Leaving mDNS multicast group on interface br0.IPv6 with address 2a00:6020:12b2:4567:89ca:80ff:fe78:ae7a.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[4102]: Leaving mDNS multicast group on interface br0.IPv4 with address 192.168.178.145.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[4102]: avahi-daemon 0.8 exiting.
Aug 17 10:28:38 MeshifyUnraid root: Starting Avahi mDNS/DNS-SD Daemon: /usr/sbin/avahi-daemon -D
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Found user 'avahi' (UID 61) and group 'avahi' (GID 214).
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Successfully dropped root privileges.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: avahi-daemon 0.8 starting up.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Successfully called chroot().
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Successfully dropped remaining capabilities.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Loading service file /services/sftp-ssh.service.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Loading service file /services/smb.service.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Loading service file /services/ssh.service.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Joining mDNS multicast group on interface br0.IPv6 with address 2a00:6020:12b2:4567:89ca:80ff:fe78:ae7a.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: New relevant interface br0.IPv6 for mDNS.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Joining mDNS multicast group on interface br0.IPv4 with address 192.168.178.145.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: New relevant interface br0.IPv4 for mDNS.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Network interface enumeration completed.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Registering new address record for 2a00:6020:12b2:4567:89ca:80ff:fe78:ae7a on br0.*.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Registering new address record for 192.168.178.145 on br0.IPv4.
Aug 17 10:28:38 MeshifyUnraid avahi-daemon[5402]: Failed to parse address 'fe80::1ae8:29ff:fe42:1f04%br0', ignoring.
Aug 17 10:28:38 MeshifyUnraid emhttpd: shcmd (66): /etc/rc.d/rc.avahidnsconfd restart
Aug 17 10:28:38 MeshifyUnraid root: Stopping Avahi mDNS/DNS-SD DNS Server Configuration Daemon: stopped
Aug 17 10:28:38 MeshifyUnraid root: Starting Avahi mDNS/DNS-SD DNS Server Configuration Daemon:  /usr/sbin/avahi-dnsconfd -D
Aug 17 10:28:38 MeshifyUnraid avahi-dnsconfd[5411]: Successfully connected to Avahi daemon.

     

    Edited by lucahammer
    Link to comment
    bonienl
    On 8/17/2023 at 11:20 AM, lucahammer said:

    Content of resolv.conf 

    # Generated by dhcpcd from br0.dhcp, br0.ra
domain localdomain
nameserver 192.168.178.2
nameserver fe80::1ae8:29ff:fe42:1f04%br0

     

    When DHCP is used then the server obtains the DNS information from your router.

    Using a link-local address as DNS server is wrong and your router should be configured with a global DNS server address instead. This could be the IPv6 address of the router itself (if it can act as DNS forwarder) or a public DNS server address.

     

    Alternatively you can set a static DNS entry in the Unraid network settings. e.g. 2001:4860:4860::8888 and/or 2001:4860:4860::8844 (google DNS servers)

     

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    Thx And Bye
    9 hours ago, bonienl said:

    When DHCP is used then the server obtains the DNS information from your router.

    Using a link-local address as DNS server is wrong and your router should be configured with a global DNS server address instead.

     

    This is the default behavior for many routers (e.g. OpenWRT) if IPv6 is enabled and the router handles DNS forward. 

    By default they then advertise their own local IPv4 and link-local/ULA IPv6 as DNS servers via DHCP.

    Usually to support DNS resolutions for your local devices. You wouldn't want to advertise a global DNS server via DHCP in this case.

    Edited by Thx And Bye
    Link to comment
    bonienl
    6 hours ago, Thx And Bye said:

    This is the default behavior for many routers (e.g. OpenWRT) if IPv6 is enabled and the router handles DNS forward. 

    By default they then advertise their own local IPv4 and link-local/ULA IPv6 as DNS servers via DHCP.

    Usually to support DNS resolutions for your local devices. You wouldn't want to advertise a global DNS server via DHCP in this case.

     

    Thanks for this explanation, I was not aware of this implementation.

    I have set up a local DNS server (pihole) and configured my router to provide clients with the IP address of pihole as DNS server, this is working fine in combination with DHCP/SLAAC.

     

    As far as I know we haven't changed the "dhcpcd" package which is handling all DHCP requests.

    Not sure why dhcpcd would add the interface name to the IP address, this is clearly not needed (wrong).

     

    Perhaps a workaround is to set a static DNS server entry and use the given LL IPv6 address.

     

    Link to comment
    bonienl

    I did a quick test and set the DNSv6 server to the link local address of my router, and this works.

     

    image.png

     

    This is how my resolv.conf file looks like. 

    # Generated by dhcpcd from bond0.dhcp
domain bergware.com
nameserver 10.0.101.100
nameserver 10.0.101.200
# Generated by rc.inet1
nameserver fe80::1ae8:29ff:febd:80c7

     

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