No DNS resolution after apt-get upgrade (openhabian)

Hi jfb,

the router is using 217.0.43.65 as primary and 217.0.43.81 as secondary DNS server. These are given by my provider and cannot be changed.
I am using an old switch with OpenWrt as DHCP server. There I configured pi-hole to be advertised as DNS server(192.168.2.3). So all clients are configured to use pi-hole which worked perfectly before the upgrade.

The output of cat /etc/resolv.conf is

# 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
nameserver 192.168.2.1

BUT, this was changed by me "quick and dirty" to be able to upload the debug log. I did the following steps:

sudo systemctl stop resolvconf     # otherwise my changes would be overwritten immediately
vim /etc/resolf.conf: Enter nameserver 192.168.2.1 (router)
sudo systemctl restart networking

To show you the "original state", I rebooted pi-hole to revert my changes and then cat /etc/resolv.conf says

# 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
nameserver 127.0.0.1

And for completeness I also created a new debug log, which I unfortunately have to paste here as pi-hole cannot upload it:

This process collects information from your Pi-hole, and optionally uploads it to a unique and random directory on tricorder.pi-hole.net.

The intent of this script is to allow users to self-diagnose their installations.  This is accomplished by running tests against our software and providing the user with links to FAQ articles when a problem is detected.  Since we are a small team and Pi-hole has been growing steadily, it is our hope that this will help us spend more time on development.

NOTE: All log files auto-delete after 48 hours and ONLY the Pi-hole developers can access your data via the given token. We have taken these extra steps to secure your data and will work to further reduce any personal information gathered.

*** [ INITIALIZING ]
[i] 2018-09-07:09:15:53 debug log has been initialized.

*** [ INITIALIZING ] Sourcing setup variables
[i] Sourcing /etc/pihole/setupVars.conf...

*** [ DIAGNOSING ]: Core version
[i] Core: v4.0 (https://discourse.pi-hole.net/t/how-do-i-update-pi-hole/249)
[i] Branch: master
[i] Commit: v4.0-0-gddbdb51

*** [ DIAGNOSING ]: Web version
[i] Web: v4.0 (https://discourse.pi-hole.net/t/how-do-i-update-pi-hole/249)
[i] Branch: master
[i] Commit: v4.0-0-gaf8c926c

*** [ DIAGNOSING ]: FTL version
[✓] FTL: v4.0 (https://discourse.pi-hole.net/t/how-do-i-update-pi-hole/249)

*** [ DIAGNOSING ]: dnsmasq version
[i] 340:

*** [ DIAGNOSING ]: lighttpd version
[i] 1.4.45

*** [ DIAGNOSING ]: php version
[i] 7.0.30

*** [ DIAGNOSING ]: Operating system
[✓] Raspbian GNU/Linux 9 (stretch)

*** [ DIAGNOSING ]: SELinux
[i] SELinux not detected

*** [ DIAGNOSING ]: Processor
[✓] armv7l

*** [ DIAGNOSING ]: Networking
[✓] IPv4 address(es) bound to the eth0 interface:
   192.168.2.3/24 matches the IP found in /etc/pihole/setupVars.conf

[✓] IPv6 address(es) bound to the eth0 interface:
   2003:e1:5713:c843:98bc:9e7f:10fa:2c03 does not match the IP found in /etc/pihole/setupVars.conf (https://discourse.pi-hole.net/t/use-ipv6-ula-addresses-for-pi-hole/2127)
   fd4b:d998:8418:1:6d2:a6ec:3412:f27b matches the IP found in /etc/pihole/setupVars.conf
   fe80::ff40:ef0b:609d:f92e does not match the IP found in /etc/pihole/setupVars.conf (https://discourse.pi-hole.net/t/use-ipv6-ula-addresses-for-pi-hole/2127)

   ^ Please note that you may have more than one IP address listed.
   As long as one of them is green, and it matches what is in /etc/pihole/setupVars.conf, there is no need for concern.

   The link to the FAQ is for an issue that sometimes occurs when the IPv6 address changes, which is why we check for it.

[i] Default IPv4 gateway: 192.168.2.1
   * Pinging 192.168.2.1...
[✓] Gateway responded.
[i] Default IPv6 gateway: fe80::1
   * Pinging fe80::1...
[✓] Gateway responded.

*** [ DIAGNOSING ]: Ports in use
*:1883 mosquitto (IPv4)
*:1883 mosquitto (IPv6)
127.0.0.1:44727 java (IPv6)
*:5007 java (IPv6)
127.0.0.1:8101 java (IPv6)
*:8443 java (IPv6)
*:8080 java (IPv6)
*:9126 java (IPv6)
*:9001 node (IPv4)
*:22 sshd (IPv4)
*:22 sshd (IPv6)
*:80 lighttpd (IPv4)
*:80 lighttpd (IPv6)
*:2001 homegear (IPv6)
*:2002 homegear (IPv6)
*:2003 homegear (IPv6)
*:53 pihole-FTL (IPv4)
*:53 pihole-FTL (IPv6)
127.0.0.1:4711 pihole-FTL (IPv4)
[::1]:4711 pihole-FTL (IPv6)
*:445 smbd (IPv6)
*:139 smbd (IPv6)
*:445 smbd (IPv4)
*:139 smbd (IPv4)

*** [ DIAGNOSING ]: Name resolution (IPv4) using a random blocked domain and a known ad-serving domain
[✓] ad.doubleclick.net.16011.9088.302br.net is  via localhost (127.0.0.1)
[✓] ad.doubleclick.net.16011.9088.302br.net is  via Pi-hole (192.168.2.3)
[✓] doubleclick.com is 216.58.207.174 via a remote, public DNS server (8.8.8.8)

*** [ DIAGNOSING ]: Name resolution (IPv6) using a random blocked domain and a known ad-serving domain
[✓] bsads.looksmart.com is  via localhost (::1)
[✓] bsads.looksmart.com is  via Pi-hole (fd4b:d998:8418:1:6d2:a6ec:3412:f27b)
[✓] doubleclick.com is 2a00:1450:4016:80b::200e via a remote, public DNS server (2001:4860:4860::8888)

*** [ DIAGNOSING ]: Pi-hole processes
[✗] dnsmasq daemon is inactive
[✓] lighttpd daemon is active
[✓] pihole-FTL daemon is active

*** [ DIAGNOSING ]: Setup variables
    PIHOLE_INTERFACE=eth0
    IPV4_ADDRESS=192.168.2.3/24
    IPV6_ADDRESS=fd4b:d998:8418:1:6d2:a6ec:3412:f27b
    QUERY_LOGGING=true
    INSTALL_WEB_SERVER=true
    INSTALL_WEB_INTERFACE=true
    LIGHTTPD_ENABLED=true
    DNSMASQ_LISTENING=single
    PIHOLE_DNS_1=192.168.2.1#53
    DNS_FQDN_REQUIRED=false
    DNS_BOGUS_PRIV=false
    DNSSEC=false
    CONDITIONAL_FORWARDING=false

*** [ DIAGNOSING ]: Dashboard and block page
[✓] Block page X-Header: X-Pi-hole: A black hole for Internet advertisements.
[✓] Web interface X-Header: X-Pi-hole: The Pi-hole Web interface is working!

*** [ DIAGNOSING ]: Gravity list
-rw-r--r-- 1 root root 3050804 Sep  2 21:38 /etc/pihole/gravity.list
   -----head of gravity.list------
   0.0.0.0
   0.r.msn.com
   0.start.bz
   000.0x1f4b0.com

   -----tail of gravity.list------
   zzz.clickbank.net
   zzzezeroe.fr
   zzzpooeaz-france.com
   zzzrtrcm2.com

*** [ DIAGNOSING ]: contents of /etc/pihole

-rw-r--r-- 1 root root 381 Aug 29 09:52 /etc/pihole/adlists.list
   https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts
   https://mirror1.malwaredomains.com/files/justdomains
   http://sysctl.org/cameleon/hosts
   https://zeustracker.abuse.ch/blocklist.php?download=domainblocklist
   https://s3.amazonaws.com/lists.disconnect.me/simple_tracking.txt
   https://s3.amazonaws.com/lists.disconnect.me/simple_ad.txt
   https://hosts-file.net/ad_servers.txt

-rw-r--r-- 1 root root 0 Jul 28 09:51 /etc/pihole/blacklist.txt

-rw-r--r-- 1 root root 124 Sep  2 21:38 /etc/pihole/local.list
   192.168.2.3 raspi
   fd4b:d998:8418:1:6d2:a6ec:3412:f27b raspi
   192.168.2.3 pi.hole
   fd4b:d998:8418:1:6d2:a6ec:3412:f27b pi.hole

-rw-r--r-- 1 root root 234 Aug  8 11:15 /etc/pihole/logrotate
   /var/log/pihole.log {
   	su root root
   	daily
   	copytruncate
   	rotate 5
   	compress
   	delaycompress
   	notifempty
   	nomail
   }
   /var/log/pihole-FTL.log {
   	su root root
   	weekly
   	copytruncate
   	rotate 3
   	compress
   	delaycompress
   	notifempty
   	nomail
   }

-rw-r--r-- 1 root root 0 Jun 16 18:39 /etc/pihole/whitelist.txt

*** [ DIAGNOSING ]: contents of /etc/dnsmasq.d

-rw-r--r-- 1 root root 1500 Aug 31 14:10 /etc/dnsmasq.d/01-pihole.conf
   addn-hosts=/etc/pihole/gravity.list
   addn-hosts=/etc/pihole/black.list
   addn-hosts=/etc/pihole/local.list
   localise-queries
   no-resolv
   cache-size=10000
   log-queries=extra
   log-facility=/var/log/pihole.log
   local-ttl=2
   log-async
   server=192.168.2.1
   interface=eth0

*** [ DIAGNOSING ]: contents of /etc/lighttpd

-rw-r--r-- 1 root root 3027 Aug  8 11:15 /etc/lighttpd/lighttpd.conf
   server.modules = (
   	"mod_access",
   	"mod_accesslog",
   	"mod_auth",
   	"mod_expire",
   	"mod_compress",
   	"mod_redirect",
   	"mod_setenv",
   	"mod_rewrite"
   )
   server.document-root        = "/var/www/html"
   server.error-handler-404    = "pihole/index.php"
   server.upload-dirs          = ( "/var/cache/lighttpd/uploads" )
   server.errorlog             = "/var/log/lighttpd/error.log"
   server.pid-file             = "/var/run/lighttpd.pid"
   server.username             = "www-data"
   server.groupname            = "www-data"
   server.port                 = 80
   accesslog.filename          = "/var/log/lighttpd/access.log"
   accesslog.format            = "%{%s}t|%V|%r|%s|%b"
   index-file.names            = ( "index.php", "index.html", "index.lighttpd.html" )
   url.access-deny             = ( "~", ".inc", ".md", ".yml", ".ini" )
   static-file.exclude-extensions = ( ".php", ".pl", ".fcgi" )
   compress.cache-dir          = "/var/cache/lighttpd/compress/"
   compress.filetype           = ( "application/javascript", "text/css", "text/html", "text/plain" )
   include_shell "/usr/share/lighttpd/use-ipv6.pl " + server.port
   include_shell "/usr/share/lighttpd/create-mime.assign.pl"
   include_shell "find /etc/lighttpd/conf-enabled -name '*.conf' -a ! -name 'letsencrypt.conf' -printf 'include \"%p\"
' 2>/dev/null"
   $HTTP["url"] =~ "^/admin/" {
       
       setenv.add-response-header = (
           "X-Pi-hole" => "The Pi-hole Web interface is working!",
           "X-Frame-Options" => "DENY"
       )
       $HTTP["url"] =~ ".ttf$" {
           
           setenv.add-response-header = ( "Access-Control-Allow-Origin" => "*" )
       }
   }
   $HTTP["url"] =~ "^/admin/\.(.*)" {
        url.access-deny = ("")
   }
   include_shell "cat external.conf 2>/dev/null"

*** [ DIAGNOSING ]: contents of /etc/cron.d

-rw-r--r-- 1 root root 1496 Aug  8 11:15 /etc/cron.d/pihole
   25 3   * * 7   root    PATH="$PATH:/usr/local/bin/" pihole updateGravity
   00 00   * * *   root    PATH="$PATH:/usr/local/bin/" pihole flush once quiet
   @reboot root /usr/sbin/logrotate /etc/pihole/logrotate
   */10 *  * * *   root    PATH="$PATH:/usr/local/bin/" pihole updatechecker local
   37 19  * * *   root    PATH="$PATH:/usr/local/bin/" pihole updatechecker remote
   @reboot root    PATH="$PATH:/usr/local/bin/" pihole updatechecker remote reboot

*** [ DIAGNOSING ]: contents of /var/log/lighttpd

-rw-r--r-- 1 www-data www-data 558 Sep  7 09:02 /var/log/lighttpd/error.log
   2018-09-03 06:25:04: (server.c.1534) logfiles cycled UID = 0 PID = 28557 
   2018-09-03 09:56:30: (server.c.1828) server stopped by UID = 0 PID = 1 
   2018-09-03 09:57:30: (log.c.217) server started 
   2018-09-03 17:01:04: (server.c.1828) server stopped by UID = 0 PID = 1 
   2018-09-03 17:02:04: (log.c.217) server started 
   2018-09-03 17:12:21: (server.c.1828) server stopped by UID = 0 PID = 1 
   2018-09-03 17:13:19: (log.c.217) server started 
   2018-09-07 09:01:52: (server.c.1828) server stopped by UID = 0 PID = 1 
   2018-09-07 09:02:52: (log.c.217) server started 

*** [ DIAGNOSING ]: contents of /var/log

-rw-r--r-- 1 pihole pihole 2987 Sep  7 09:03 /var/log/pihole-FTL.log
   -----head of pihole-FTL.log------
   [2018-09-07 09:03:00.185] ########## FTL started! ##########
   [2018-09-07 09:03:00.185] FTL branch: 
   [2018-09-07 09:03:00.185] FTL version: v4.0
   [2018-09-07 09:03:00.186] FTL commit: 8493df4
   [2018-09-07 09:03:00.186] FTL date: 2018-08-05 13:40:30 -0700
   [2018-09-07 09:03:00.186] FTL user: pihole
   [2018-09-07 09:03:00.188] Starting config file parsing (/etc/pihole/pihole-FTL.conf)
   [2018-09-07 09:03:00.189]    SOCKET_LISTENING: only local
   [2018-09-07 09:03:00.189]    AAAA_QUERY_ANALYSIS: Show AAAA queries
   [2018-09-07 09:03:00.189]    MAXDBDAYS: max age for stored queries is 365 days
   [2018-09-07 09:03:00.189]    RESOLVE_IPV6: Resolve IPv6 addresses
   [2018-09-07 09:03:00.190]    RESOLVE_IPV4: Resolve IPv4 addresses
   [2018-09-07 09:03:00.190]    DBINTERVAL: saving to DB file every 3600 seconds
   [2018-09-07 09:03:00.190]    DBFILE: Using /etc/pihole/pihole-FTL.db
   [2018-09-07 09:03:00.190]    MAXLOGAGE: Importing up to 24.0 hours of log data
   [2018-09-07 09:03:00.190]    PRIVACYLEVEL: Set to 0
   [2018-09-07 09:03:00.191]    IGNORE_LOCALHOST: Show queries from localhost
   [2018-09-07 09:03:00.191]    BLOCKINGMODE: Null IPs for blocked domains
   [2018-09-07 09:03:00.191]    REGEX_DEBUGMODE: Inactive
   [2018-09-07 09:03:00.191] Finished config file parsing
   [2018-09-07 09:03:00.191] Compiled 0 Regex filters and 0 whitelisted domains in 0.4 msec (0 errors)
   [2018-09-07 09:03:00.228] Database successfully initialized
   [2018-09-07 09:03:00.251] Notice: Increasing queries struct size from 0 to 10000
   [2018-09-07 09:03:00.252] Notice: Increasing domains struct size from 0 to 1000
   [2018-09-07 09:03:00.252] Notice: Increasing clients struct size from 0 to 10
   [2018-09-07 09:03:00.252] New forward server: 192.168.2.1 (0/0)
   [2018-09-07 09:03:00.252] Notice: Increasing forwarded struct size from 0 to 4
   [2018-09-07 09:03:00.252] Notice: Increasing overTime struct size from 0 to 100
   [2018-09-07 09:03:00.309] Imported 2615 queries from the long-term database
   [2018-09-07 09:03:00.309]  -> Total DNS queries: 2615
   [2018-09-07 09:03:00.309]  -> Cached DNS queries: 444
   [2018-09-07 09:03:00.310]  -> Forwarded DNS queries: 2171
   [2018-09-07 09:03:00.310]  -> Exactly blocked DNS queries: 0
   [2018-09-07 09:03:00.310]  -> Unknown DNS queries: 0
   [2018-09-07 09:03:00.310]  -> Unique domains: 460

   -----tail of pihole-FTL.log------
   [2018-09-07 09:03:00.189]    RESOLVE_IPV6: Resolve IPv6 addresses
   [2018-09-07 09:03:00.190]    RESOLVE_IPV4: Resolve IPv4 addresses
   [2018-09-07 09:03:00.190]    DBINTERVAL: saving to DB file every 3600 seconds
   [2018-09-07 09:03:00.190]    DBFILE: Using /etc/pihole/pihole-FTL.db
   [2018-09-07 09:03:00.190]    MAXLOGAGE: Importing up to 24.0 hours of log data
   [2018-09-07 09:03:00.190]    PRIVACYLEVEL: Set to 0
   [2018-09-07 09:03:00.191]    IGNORE_LOCALHOST: Show queries from localhost
   [2018-09-07 09:03:00.191]    BLOCKINGMODE: Null IPs for blocked domains
   [2018-09-07 09:03:00.191]    REGEX_DEBUGMODE: Inactive
   [2018-09-07 09:03:00.191] Finished config file parsing
   [2018-09-07 09:03:00.191] Compiled 0 Regex filters and 0 whitelisted domains in 0.4 msec (0 errors)
   [2018-09-07 09:03:00.228] Database successfully initialized
   [2018-09-07 09:03:00.251] Notice: Increasing queries struct size from 0 to 10000
   [2018-09-07 09:03:00.252] Notice: Increasing domains struct size from 0 to 1000
   [2018-09-07 09:03:00.252] Notice: Increasing clients struct size from 0 to 10
   [2018-09-07 09:03:00.252] New forward server: 192.168.2.1 (0/0)
   [2018-09-07 09:03:00.252] Notice: Increasing forwarded struct size from 0 to 4
   [2018-09-07 09:03:00.252] Notice: Increasing overTime struct size from 0 to 100
   [2018-09-07 09:03:00.309] Imported 2615 queries from the long-term database
   [2018-09-07 09:03:00.309]  -> Total DNS queries: 2615
   [2018-09-07 09:03:00.309]  -> Cached DNS queries: 444
   [2018-09-07 09:03:00.310]  -> Forwarded DNS queries: 2171
   [2018-09-07 09:03:00.310]  -> Exactly blocked DNS queries: 0
   [2018-09-07 09:03:00.310]  -> Unknown DNS queries: 0
   [2018-09-07 09:03:00.310]  -> Unique domains: 460
   [2018-09-07 09:03:00.310]  -> Unique clients: 10
   [2018-09-07 09:03:00.310]  -> Known forward destinations: 1
   [2018-09-07 09:03:00.311] Successfully accessed setupVars.conf
   [2018-09-07 09:03:00.331] PID of FTL process: 1024
   [2018-09-07 09:03:00.331] Listening on port 4711 for incoming IPv4 telnet connections
   [2018-09-07 09:03:00.332] Listening on port 4711 for incoming IPv6 telnet connections
   [2018-09-07 09:03:00.333] Listening on Unix socket
   [2018-09-07 09:03:00.348] Compiled 0 Regex filters and 0 whitelisted domains in 0.2 msec (0 errors)
   [2018-09-07 09:03:19.340] Notice: Increasing clients struct size from 10 to 20
   [2018-09-07 09:03:19.341] Notice: Increasing overTime struct size from 100 to 200

*** [ DIAGNOSING ]: Locale
    LANG=en_US.UTF-8

*** [ DIAGNOSING ]: Pi-hole log
-rw-r--r-- 1 pihole pihole 0 Sep  7 09:02 /var/log/pihole.log
   -----head of pihole.log------

Kind regards,
ping