Question.

[mcc@mastodon.social]

Question.

- I use Debian 13 Linux.
- mDNS is an absolutely critical part of several things I do.
- Say on this network I have a Windows machine named "desktop" and a Linux machine named "laptop".
- On Linux, I type "ping desktop.local". Success. I "ping laptop.local". Failure. I "ping laptop". Success.
- Two months ago I am certain laptop.local resolved on the laptop.
- I *think* my mdns is provided by avahi, or at least apt-cache policy says avahi-daemon is installed.

How do I proceed?

[mcc@mastodon.social]

Oh, additionally, although ping is able to "ping laptop", if I open a local web server at port 8000 and then connect to "http://laptop:8000" in firefox, it does not connect. This was something that previously worked, when laptop.local was working.

[fishidwardrobe@mastodon.me.uk]

@mcc check /etc/hosts? i know this is a question about DNS, really. but.

[90sscriptkiddiw@kolektiva.social]

@mcc you may have to configure your browser NOT to use DNS over HTTPS, I had a similar problem at one point and that was the solution.

[mcc@mastodon.social]

- vi /etc/avahi/avahi-daemon.conf
- there is a line right there, under [publish], saying publish-workstation=no
- change it to yes
- sudo systemctl restart avahi-daemon.service
- it works now

This all makes sense but??? Why???? Was it working??? Two months ago ?!?!?!?

[fcbsd@hachyderm.io]

@mcc is the default no? and an update has switched it back to default?

[mcc@mastodon.social]

@fcbsd Who controls the contents of /etc/avahi/avahi-daemon.conf? The Debian installer, or me? I sincerely do not know the answer to this question

[sidneys1@infosec.exchange]

@90sScriptKiddiw @mcc or (at least for Firefox) there’s an exception list to not use DOH for

[90sscriptkiddiw@kolektiva.social]

@mcc huh, weird, good to know! 🧐

[eramdam@social.erambert.me]

@mcc idk if that’s related but I remember avahi-daemon needing to be restarted often back when I relied on it for one of my machines at home. It just Stopped Working randomly and restarting the service was the only fix lolsob

[lambdageek@mastodon.social]

@mcc I'm on a debian forky/sid chimera.
My avahi-daemon.conf has publish-workstation=no

I can nonetheless ping MYMACHINENAME.local

https://askubuntu.com/questions/1517402/cannot-resolve-own-local-avahi-hostname suggests checking your nssswitch.conf and making sure libnss-mdns is installed although it seems like not having that woudl break all mdns

[tezoatlipoca@mas.to]

@mcc have a backup from in between the before-working and now-working that shows avahi-daemon.conf turning it off? mebbe an update pushed the =no setting?

(probably not worth the effort given everything is working again; unless figuring _why_ it didn't work in the interim is a drive)

[mcc@mastodon.social]

This is deeply upsetting https://mastodon.social/@lambdageek/116099461735423343

Another upsetting thing: Apparently systemd has its own mdns setup: https://www.reddit.com/r/debian/comments/1mnvzln/the_debian_technical_committee_made_a_baffling/ which Debian may, or may not, have disabled intentionally in Debian 13 (the file this poster claims is present is not present) because they expect they use Avahi instead. I don't understand why I'd use Avahi instead of systemd, or, if I decided systemd's mdns were better, how I'd switch to it.

[mcc@mastodon.social]

@lambdageek That's very interesting… to your knowledge, am I doing something *wrong* if I just switch publish-workstation to yes?

As far as I know what you just said is *correct*, but the fact I know what avahi is, but I don't know what nssswitch/libnss-mdns are, makes me nervous about touching the latter when making a change to avahi worked

[munin@infosec.exchange]

@mcc

oh for fuck's sake

[bytex64@awesome.garden]

@mcc @tezoatlipoca That’s what I was thinking but I looked at the avahi-daemon Debian changelog and not only is there nothing about that, there hasn’t been an update for about eight months.

[brooke@bikeshed.vibber.net]

@mcc mdns is haunted

[lambdageek@mastodon.social]

@mcc I have no idea what i'm doing :-(

Just a guess: did sudo systemctl restart avahi-daemon.service in fact restart avahi? or did it start it? Maybe it wasn't running before?

what happens if you change the setting back to "no" and restart?

[elomatreb@chaos.social]

@mcc for historical reasons the primary interface for software that wants to interact with mdns beyond simple name to IP resolution is the Avahi daemon dbus interface, and systemd-resolved does not implement that.

[mcc@mastodon.social]

@elomatreb ow. ow. ow. ow. ow.

thanks for the explanation.