Questions[mdns](ubuntu)

Resolving .local hostnames has become slow since updated from 18.04 to 20.04. Things as simple as:

ping flibble.local

work immediately in 18.04, but take about 5 seconds or so in 20.04, after which it behaves normally. However, it still takes another 5 seconds when run again.

I haven't customized anything since updating. If it matters, Ubuntu is running as a VM in Parallels. I can provide details as necessary.

My /etc/nsswitch.conf file contains the usual:

hosts:          files mdns4_minimal [NOTFOUND=return] dns myhostname

I've tried searching for solutions to this problem, but nothing so far has fixed it.

systemctl status systemd-resolved.service output:

● systemd-resolved.service - Network Name Resolution
     Loaded: loaded (/lib/systemd/system/systemd-resolved.service; enabled; vendor preset: enabled)
     Active: active (running) since Mon 2020-10-05 09:55:47 PDT; 10min ago
       Docs: man:systemd-resolved.service(8)
             https://www.freedesktop.org/wiki/Software/systemd/resolved
             https://www.freedesktop.org/wiki/Software/systemd/writing-network-configuration-managers
             https://www.freedesktop.org/wiki/Software/systemd/writing-resolver-clients
   Main PID: 592 (systemd-resolve)
     Status: "Processing requests..."
      Tasks: 1 (limit: 7061)
     Memory: 9.4M
     CGroup: /system.slice/systemd-resolved.service
             └─592 /lib/systemd/systemd-resolved

Oct 05 09:55:47 invasion-ubuntu20 systemd[1]: Starting Network Name Resolution...
Oct 05 09:55:47 invasion-ubuntu20 systemd-resolved[592]: Positive Trust Anchors:
Oct 05 09:55:47 invasion-ubuntu20 systemd-resolved[592]: . IN DS 20326 8 2 e06d44b80b8f1d39a95c0b0d7c65d08458e880409bbc683457104237c7f8ec8d
Oct 05 09:55:47 invasion-ubuntu20 systemd-resolved[592]: Negative trust anchors: 10.in-addr.arpa 16.172.in-addr.arpa 17.172.in-addr.arpa 18.172.in-addr.arpa 19.172.>
Oct 05 09:55:47 invasion-ubuntu20 systemd-resolved[592]: Using system hostname 'invasion-ubuntu20'.
Oct 05 09:55:47 invasion-ubuntu20 systemd[1]: Started Network Name Resolution.
Oct 05 09:55:47 invasion-ubuntu20 systemd-resolved[592]: Using degraded feature set (UDP) for DNS server 192.168.6.1.

I am having issues getting my servers to talk to each other via mDNS / Avahi.

I have two servers, an Ubuntu Server and a Raspberry PI.

user@WORKCOM9001~ ()$ sudo service avahi-daemon status
● avahi-daemon.service - Avahi mDNS/DNS-SD Stack
     Loaded: loaded (/lib/systemd/system/avahi-daemon.service; enabled; vendor preset: enabled)
     Active: active (running) since Wed 2020-07-01 21:54:45 PDT; 4min 6s ago
TriggeredBy: ● avahi-daemon.socket
   Main PID: 1101 (avahi-daemon)
     Status: "avahi-daemon 0.7 starting up."
      Tasks: 2 (limit: 18921)
     Memory: 2.5M
     CGroup: /system.slice/avahi-daemon.service
             ├─1101 avahi-daemon: running [WORKCOM9001.local]
             └─1160 avahi-daemon: chroot helper

And on my Raspberry PI I get:

pi@raspberrypi2:~ $ sudo service avahi-daemon status
● avahi-daemon.service - Avahi mDNS/DNS-SD Stack
   Loaded: loaded (/lib/systemd/system/avahi-daemon.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2020-07-01 18:36:47 PDT; 3h 21min ago
 Main PID: 276 (avahi-daemon)
   Status: "avahi-daemon 0.7 starting up."
   Memory: 956.0K
   CGroup: /system.slice/avahi-daemon.service
           ├─276 avahi-daemon: running [raspberrypi2.local]
           └─287 avahi-daemon: chroot helper

I can ping and SSH into each one from the other with IP address (i.e. ssh [email protected]) works but with hostname + .local it does not.

But avahi-browse does not show either device from the other. (i.e. from my server):

+ wlp61s0 IPv6 EPSON XP-830 Series                           _uscan._tcp          local
+ wlp61s0 IPv4 EPSON XP-830 Series                           _uscan._tcp          local
+ wlp61s0 IPv6 EPSON XP-830 Series                           _privet._tcp         local
+ wlp61s0 IPv4 EPSON XP-830 Series                           _privet._tcp         local
+ wlp61s0 IPv6 EPSON XP-830 Series                           Secure Internet Printer local
+ wlp61s0 IPv4 EPSON XP-830 Series                           Secure Internet Printer local
+ wlp61s0 IPv6 EPSON XP-830 Series                           Internet Printer     local
+ wlp61s0 IPv4 EPSON XP-830 Series                           Internet Printer     local
+ wlp61s0 IPv6 EPSON XP-830 Series                           _scanner._tcp        local
+ wlp61s0 IPv4 EPSON XP-830 Series                           _scanner._tcp        local
+ wlp61s0 IPv6 EPSON XP-830 Series                           Microsoft Windows Network local
+ wlp61s0 IPv4 EPSON XP-830 Series                           Microsoft Windows Network local
+ wlp61s0 IPv6 EPSON XP-830 Series                           Web Site             local
+ wlp61s0 IPv4 EPSON XP-830 Series                           Web Site             local
+ wlp61s0 IPv6 EPSON XP-830 Series                           PDL Printer          local
+ wlp61s0 IPv4 EPSON XP-830 Series                           PDL Printer          local
+ wlp61s0 IPv6 EPSON XP-830 Series                           UNIX Printer         local
+ wlp61s0 IPv4 EPSON XP-830 Series                           UNIX Printer         local
+ wlp61s0 IPv6 5c:1d:d9:8f:a4:05@fe80::5e1d:d9ff:fe8f:a405   _apple-mobdev2._tcp  local
+ wlp61s0 IPv4 5c:1d:d9:8f:a4:05@fe80::5e1d:d9ff:fe8f:a405   _apple-mobdev2._tcp  local
+ wlp61s0 IPv4 Chromecast-Ultra-a41f56bb802c5975b2ecb845394ab75d _googlecast._tcp     local
+ wlp61s0 IPv4 a41f56bb-802c-5975-b2ec-b845394ab75d          _googlezone._tcp     local

And from the Raspberry Pi:

+  wlan0 IPv6 EPSON XP-830 Series                           Internet Printer     local
+  wlan0 IPv4 EPSON XP-830 Series                           Internet Printer     local
+  wlan0 IPv6 EPSON XP-830 Series                           Secure Internet Printer local
+  wlan0 IPv4 EPSON XP-830 Series                           Secure Internet Printer local
+  wlan0 IPv4 5c:1d:d9:8f:a4:05@fe80::5e1d:d9ff:fe8f:a405   _apple-mobdev2._tcp  local
+  wlan0 IPv6 5c:1d:d9:8f:a4:05@fe80::5e1d:d9ff:fe8f:a405   _apple-mobdev2._tcp  local
+  wlan0 IPv6 EPSON XP-830 Series                           _privet._tcp         local
+  wlan0 IPv4 EPSON XP-830 Series                           _privet._tcp         local
+  wlan0 IPv4 a41f56bb-802c-5975-b2ec-b845394ab75d          _googlezone._tcp     local
+  wlan0 IPv4 EPSON XP-830 Series                           UNIX Printer         local
+  wlan0 IPv4 EPSON XP-830 Series                           PDL Printer          local
+  wlan0 IPv4 EPSON XP-830 Series                           Web Site             local
+  wlan0 IPv4 EPSON XP-830 Series                           Microsoft Windows Network local
+  wlan0 IPv4 EPSON XP-830 Series                           _scanner._tcp        local
+  wlan0 IPv4 EPSON XP-830 Series                           _uscan._tcp          local
+  wlan0 IPv6 EPSON XP-830 Series                           UNIX Printer         local
+  wlan0 IPv6 EPSON XP-830 Series                           PDL Printer          local
+  wlan0 IPv6 EPSON XP-830 Series                           Web Site             local
+  wlan0 IPv6 EPSON XP-830 Series                           Microsoft Windows Network local
+  wlan0 IPv6 EPSON XP-830 Series                           _scanner._tcp        local
+  wlan0 IPv6 EPSON XP-830 Series                           _uscan._tcp          local
+  wlan0 IPv4 Chromecast-Ultra-a41f56bb802c5975b2ecb845394ab75d _googlecast._tcp     local

Can anyone help me with this?

Thank you

I've been trying to format a Drobo to use with linux. While I was doing this ubuntu suddenly stopped resolving .local domains, breaking big parts of my configuration. I could fix this by just using the ips, but I'd really like to learn what the problem is, since I actually did not really change anything on the system configuration, especially nothing network related, most if it is rather mint.

Possibly unrelated: the only thing I tried was a .deb archive for drobo-utils, which i downloaded from their sourceforge repo. Being an abandoned project that install failed without an error. I then installed drobo-utils via apt-get install, which was an outdated version, so I uninstalled via apt-get remove and dowloaded the plain version which I ran manually. All my attempts to format the drobo failed likely to the drobo not supporting linux (don't by this overpriced crap, I regret it).

So while i was running all sorts of commands (fdisk, parted, mke2fs, as I said nothing remotely network related) I noticed my homebridge installation reporting it could not resolve a .local domain. This however is not consistent, sometimes restarting homebridge helps and it can resolve .local again, then it stops again.

I am completely clueless about what to check. Everything I find when looking for not being able to resolve .local seems either outdated or completely unrelated to my problem, I I'd like to understand what kind of commands I am pasting into my terminal, so I also did not change any configuration yet.

I'm hoping to find somebody helpful who could try figure it out with me step by step.

This seems to be a behavior difference which only started in either 18.10 or 19.04.

While avahi-resolve --name my.subdomain.local returns a valid IP address and is working it doesn't work outside of that, i.e. ping, curl or chrome.

The name resolution does still work though for subdomain.local. This seems to be related to the fact that *.subdomain.local is resolved as mDNS CNAME.

Content of nsswitch.conf

passwd:         compat systemd
group:          compat systemd
shadow:         compat
gshadow:        files

hosts:          files mdns4_minimal [NOTFOUND=return] dns
networks:       files

protocols:      db files
services:       db files
ethers:         db files
rpc:            db files

netgroup:       nis

Content of /etc/resolv.conf

nameserver 127.0.0.53
options edns0

I want to stop avahi-daemon (mDNS) and have it stay stopped.

It seems to restart a bit after midnight. Obviously some sort of periodic job is restarting it but I can't figure out what is.

TANGENT: I tried stopping avahi-daemon.service with systemctl but that did not work. Only the older style "service stop" stopped the service (albeit temporarily).