[Bug 1874021] Re: avahi-browse -av is empty, mdns not working in arduino ide

[Trent Lloyd]

OK thanks for the updates. So I can see a lot of mDNS packets in the
lp1874021.pcap capture from various sources. I can see some printers,
google cast, sonoff, etc. Curiously though when you do the avahi cache
dump it isn't seeing any of these.

Wireshark is showing malformed packets for many of the responses
strangely, the IP and UDP headers indicate a different length to that of
the actual dta. Not sure if this is an issue with wireshark, the
wireless driver or whatever mDNS implementations are replying. May need
further looking at.

But it's curious though that avahi is showing absoultely no cached
services, and that it works on ethernet, given that the lp1874021.pcap
seems to show plenty of actual mDNS packets coming and going.


Could you try start Avahi (on wireless) using --debug

(1) override the systemd config with this command:
systemctl edit avahi-daemon.service

Once the editor opens, add the following 3 lines then save and squit:

[Service]
ExecStart=
ExecStart=/usr/sbin/avahi-daemon -s --debug

Then restart avahi-daemon: sudo systemctl restart avahi-daemon.service

Lastly run "avahi-browse -av", wait a minute or two, then upload a copy
of the "journalctl -u avahi-daemon" again?

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https://bugs.launchpad.net/bugs/1874021

Title:
  avahi-browse -av is empty, mdns not working in arduino ide

Status in avahi package in Ubuntu:
  Incomplete

Bug description:
  When I started the arduino IDE my port list is empty. This list relies
  on multicast DNS which is served by avahi.

  When running the avahi-browse -av command on ubuntu 18.04 I get a list
  of al mdns devices. On ubuntu 20.04 the're no mdns devices reported.

  The avahi-daemon is running. And when executing netstat -nlp | grep
  5353 I see avahi-daemon is listening. When also running tcpdump port
  5353 I see mdns packages arriving. But still avahi-browse -av is
  empty.

  iptables -A shows no rules and policies are accept
  ufw is disabled

  I also removed apparmor but also that didn't make any difference.

  On both ubuntu 18.04 and 20.04 the avahi version is 0.7.
  ---
  ProblemType: Bug
  ApportVersion: 2.20.11-0ubuntu27
  Architecture: amd64
  CasperMD5CheckResult: skip
  CurrentDesktop: ubuntu:GNOME
  DistroRelease: Ubuntu 20.04
  InstallationDate: Installed on 2020-04-08 (13 days ago)
  InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Beta amd64 (20200402)
  Package: avahi-daemon 0.7-4ubuntu7
  PackageArchitecture: amd64
  ProcVersionSignature: Ubuntu 5.4.0-25.29-generic 5.4.30
  Tags:  focal
  Uname: Linux 5.4.0-25-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm cdrom dialout dip lpadmin lxd plugdev sambashare sudo
  _MarkForUpload: True

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