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

Mon May 29 05:03:26 UTC 2023

There's a detail in the github issue that wasn't noted here:
I have Ubuntu Server 22.04.2 running in a VM (VMWare 13.0.2) on an Apple Silicon Mac running macOS 13.4.

That makes the network driver situation less likely but the firewall
situation still possible.

A few extra questions:
What kind of network is fusion set to - bridged, nat, host-only, etc
+ If you are using bridged, but to your macs wireless adapter, I have also experienced this not working as expected. Try use ethernet via a USB-Ethernet or native ethernet if your machine has it - and see if it works then. That was the case for me. If you google "vmware fusion bridge wifi" there are lots of posts with slightly different setups and symptoms.
+ If you are using nat/host-only I would expect only to be able to resolve hostnames with the host Mac and not the rest of the network

Run tcpdump as directed, I am curious if you see any packets sent from
any other node on your network. I am guessing not. If you are, it would
be ideal to capture a pcap file (a copy of all the network packets on
5353) from both this linux VM, as well as another linux machine on the
network that is not the host mac:L

tcpdump -i <interface> -s 65535 -w lp2021409-$(hostname).pcap port 5353

Then run a query from both the VM and external host, for the other
machine. While the pcap is running. Then stop it. Upload both files and
note the IP addresses and hostnames of both machines.

It's highly likely this is not a bug in avahi or nss-mdns but a network issue of some kind. Hopefully this will get you going in the right direction.

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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:
  New
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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