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Re: How to Turn Off Autodiscovered Printers in Firefox?




On Wed 27 Sep 2017 at 14:46:22 +0000, Curt wrote:

> On 2017-09-27, Brian <ad44@xxxxxxxxxxxxxxx> wrote:
> >> 
> >> When I tried this, it solved my problem, and I don't notice any delay
> >> issues.
> >
> > Users of Qt apps, command line utilities and LibreOffice would not be
> > overjoyed by having their printing experience severely degraded. There
> > might also be other drawbacks to dbus deactivation. The issue with an
> > "anonymous joe" is the lack of any detail, explanation or testing
> > reports.
> 
> Well Joe(s) said:
> 
>  The cups client libraries now also get a list of network printers from Avahi.
>  In older versions of cups, this was only done by the cups server.

Ok.

>  This is now done in the client-side cups libraries (ie libcups.so, 
>  which GNOME and KDE apps link against) and not in the cupsd server. 
>  So changing the "Browse" settings in the cups server won't work.

Ok.
 
>  $ ldd /usr/lib/x86_64-linux-gnu/libcups.so.2
>  ...
>  libavahi-common.so.3 => /usr/lib/x86_64-linux-gnu/libavahi-common.so.3
>  libavahi-client.so.3 => /usr/lib/x86_64-linux-gnu/libavahi-client.so.3
> 
>  IE this behaviour (of showing remote printers in the Print dialog box) happens
>  even if you turn off your local cups server. You can disable it by turning off
>  the avahi service, but that will disable all zeroconf/mdns related
>  functionality.

Your first point applies only to GTK applications, not to Qt and command
line applications and LibreOffice. They need cups-browsed. The second
point is swings and roundabouts; at least until GTK and/or GNOME gets
its act together. [1]
 
>  However, there is at least a way to turn off most of avahi's functionality
>  (including adding remote printers into the CUPS clients) while keeping the DNS
>  functionality (eg when looking up foo.local-style host names):
>  edit /etc/avahi/avahi-daemon.conf and in the [server] section, add
>  enable-dbus=no then restart the avahi-daemon service.

I've not disagreed with that, only with the idea it is a wise thing to
do. Most printing operations are user controlled; the intervention of
the superuser is rarely needed. This change to avahi-daemon.conf affects
those not relying on GTK. There would be a riot here if all users lost
access to remote printers for the sake of one user not wanting to see
them in one application.
 
> I guess that's all the explanation we're going to get. As for testing, the OP
> tested and said it solved his problem. I'm sorry the solution wasn't up to your
> high standards, but I did my best.
> 
> ;-)

I also tested. It worked insofar as remote printers were not present in
the Firefox print dialog but lpstat, loptions etc took ages to display
an output. That is the third drawback to the "solution" I've pointed
out.

[1] LP #1379359
  https://bugs.launchpad.net/ubuntu/+source/gtk+3.0/+bug/1379359
leads to
  https://launchpad.net/~roman-shipovskij/+archive/ubuntu/gtk+3.0-withoutavahiprinters

-- 
Brian.