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

[Trent Lloyd]

Looking at jctl.txt things look normal, the server starts up, gets
server startup complete and then adds the appropriate IP for wlan0.
Config file looks normal.

Can you please try the following to collect extra debug info

(1) Start a tcpdump and leaving it running - tcpdump --no-promiscuous-mode -w lp1874021.pcap -i wlp1s0 port 5353 and udp 
(2) Restart avahi; sudo systemctl restart avahi-daemon
(3) Wait 10 seconds, then try run "avahi-browse -av | tee -a lp1874021-browse.txt" 
(4) Wait another 10 seconds
(5) Run: sudo killall -USR1 avahi-daemon # this dumps the avahi cache into the journal
(6) Quit avahi-browse
(7) Quit tcpdump
(8) Please then upload the lp1874021-browse.txt (copied output from avahi-browse), lp1874021.pcap (raw packet capture of mdns packets) and a copy of the output of "journalctl -u avahi-daemon"

As an extra test, after having done the above, you can try put the
interface in promiscous mode and see if that fixes the problem. This can
make Avahi work on bad network (usually wifi) drivers that do not
correctly implement multicast.

(9) sudo tcpdump -w lp1874021-promisc.pcap -i wlp1s0 port 5353 and udp 
(10) sudo systemctl restart avahi-daemon
(11) avahi-browse -av
(12) If the service still hasn't shown up, consider also then restarting whatever device is advertising the service you want to connect to. And note if it then appears after doing that.
(13) If you have the option, try to then plug in either or both devices via ethernet instead of WiFi.

If the services do start appearing at some point be sure to note which
step you were at when that happened.

Please note that all of these files will contain information about mDNS
services on your local network, typically this information is relatively
OK to be public since it would be broadcast if you were on a public WiFi
network - it can include names, mac addresses, etc. If that is a concern
to you in terms of privacy then feel free to consider either attempting
to sanitize the data (though that is difficult for the pcap file) or
setting the bug to private although we much prefer not to set bugs to
private if possible.

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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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