[Bug 2021409] Re: mdns failng with current versions of libnss-mdns and avahi-daemon

[Jeremy Sequoia]

Also:

[659] /etc/avahi/services $ avahi-browse -a
+     lo IPv4 cid                                           SSH Remote Terminal  local
+     lo IPv4 cid                                           SFTP File Transfer   local

It's as if something is causing the network interface to not support
mdns, but everyhing looks configured to me... what am I missing?  It
should really not be this difficult...

** Package changed: avahi (Ubuntu) => nss-mdns (Ubuntu)

** Also affects: avahi (Ubuntu)
   Importance: Undecided
       Status: New

** Also affects: avahi
   Importance: Undecided
       Status: New

** Bug watch added: github.com/lathiat/nss-mdns/issues #87
   https://github.com/lathiat/nss-mdns/issues/87

** Changed in: avahi
   Importance: Undecided => Unknown

** Changed in: avahi
       Status: New => Unknown

** Changed in: avahi
 Remote watch: None => github.com/lathiat/nss-mdns/issues #87

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https://bugs.launchpad.net/bugs/2021409

Title:
  mdns failng with current versions of libnss-mdns and avahi-daemon

Status in Avahi:
  Unknown
Status in avahi package in Ubuntu:
  New
Status in nss-mdns package in Ubuntu:
  New

Bug description:
  I have Ubuntu Server 22.04.2

  I have installed avahi-daemon and libnss-mdns, but mdns resolution is
  not occurring over my primary network interface:

  Note that this is with `allow-interfaces=ens160` set /etc/avahi/avahi-
  daemon.conf.

  (22:25:17 Sat May 27 2023 jeremy at cid pts/0 aarch64)
  [648] ~ $ sudo resolvectl mdns ens160 1

  (22:25:22 Sat May 27 2023 jeremy at cid pts/0 aarch64)
  [649] ~ $ resolvectl status
  Global
         Protocols: -LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported
  resolv.conf mode: stub

  Link 2 (ens160)
      Current Scopes: DNS mDNS/IPv4 mDNS/IPv6
           Protocols: +DefaultRoute +LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported
  Current DNS Server: 2601:647:6680:4b95::1
         DNS Servers: 10.1.30.1 2601:647:6680:4b95::1
          DNS Domain: localdomain

  (22:25:27 Sat May 27 2023 jeremy at cid pts/0 aarch64)
  [650] ~ $ avahi-resolve -n cid.local
  Failed to resolve host name 'cid.local': Timeout reached

  (22:26:03 Sat May 27 2023 jeremy at cid pts/0 aarch64)
  [651] ~ $ avahi-resolve -a 10.0.30.1
  Failed to resolve address '10.0.30.1': Timeout reached

  (22:26:13 Sat May 27 2023 jeremy at cid pts/0 aarch64)
  [652] ~ $ sudo systemctl status avahi-daemon
  ● avahi-daemon.service - Avahi mDNS/DNS-SD Stack
       Loaded: loaded (/lib/systemd/system/avahi-daemon.service; enabled; vendor preset: enabled)
       Active: active (running) since Sat 2023-05-27 22:22:29 UTC; 3min 51s ago
  TriggeredBy: ● avahi-daemon.socket
     Main PID: 850 (avahi-daemon)
       Status: "avahi-daemon 0.8 starting up."
        Tasks: 2 (limit: 4523)
       Memory: 1.5M
          CPU: 15ms
       CGroup: /system.slice/avahi-daemon.service
               ├─850 "avahi-daemon: running [cid.local]"
               └─891 "avahi-daemon: chroot helper"

  May 27 22:22:29 cid avahi-daemon[850]: No service file found in /etc/avahi/services.
  May 27 22:22:29 cid avahi-daemon[850]: Joining mDNS multicast group on interface ens160.IPv6 with address 2601:647:6680:4b95:20c:29ff:fe42:f399.
  May 27 22:22:29 cid avahi-daemon[850]: New relevant interface ens160.IPv6 for mDNS.
  May 27 22:22:29 cid avahi-daemon[850]: Joining mDNS multicast group on interface ens160.IPv4 with address 10.1.30.2.
  May 27 22:22:29 cid avahi-daemon[850]: New relevant interface ens160.IPv4 for mDNS.
  May 27 22:22:29 cid avahi-daemon[850]: Network interface enumeration completed.
  May 27 22:22:29 cid avahi-daemon[850]: Registering new address record for 2601:647:6680:4b95:20c:29ff:fe42:f399 on ens160.*.
  May 27 22:22:29 cid avahi-daemon[850]: Registering new address record for 10.1.30.2 on ens160.IPv4.
  May 27 22:22:30 cid avahi-daemon[850]: Server startup complete. Host name is cid.local. Local service cookie is 2371061072.
  May 27 22:26:11 cid avahi-daemon[850]: wide-area.c: Query timed out.

  (22:27:14 Sat May 27 2023 jeremy at cid pts/0 aarch64)
  [657] ~ $ grep hosts /etc/nsswitch.conf 
  hosts:          files mdns4_minimal [NOTFOUND=return] dns

  ---

  If I set 'allow-interfaces=ens160,lo`, we are able to resolve
  cid.local to localhost:

  $ avahi-resolve -n cid.local               
  cid.local	127.0.0.1

  but I cannot lookup anything else on my network via the ens160
  interface.

  I *can* resolve cid.local (10.1.30.2) from other devices on my network
  for a brief moment after I restart avahi-daemon.

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