Bug#840327: stopped working, no helpful feedback
On Tue 11 Oct 2016 at 12:19:30 +0200, Daniel Pocock wrote:
> On 11/10/16 12:02, Brian Potkin wrote:
> > [I made a mistake with my previous mail by not sending it to the BTS.
> > Because of that your reply didn't go there either. I've rectified the
> > bug record by bouncing both mails to the BTS and setting the addresses
> > correctly on this mail].
> >
> >
> > On Tue 11 Oct 2016 at 09:59:42 +0200, Daniel Pocock wrote:
> >
> >> On 10/10/16 21:22, Brian Potkin wrote:
> >>>
> >>> Printing "working fine" for a long time must indicate something to you.
> >>> Then it stops working. How is this a bug rather than a matter for
> >>> debian-user? Computer systems don't generally go into meltdown because
> >>> they feel unappreciated.
> >>
> >> The bug isn't because it stopped working (I got it working again anyway)
> >>
> >> I raised a bug because I was hoping we could improve the user experience
> >> for people who don't know how to dig around in the log files. Maybe it
> >> should be a wishlist bug.
> >
> > My view would be that with printing problems users have to be prepared
> > to dig into log files, particularly the error_log. Without it a user
> > will get nowhere -fast.
> >
> > [...Snip...]
> >
>
> In that case, we really need to anticipate having a GUI for browsing
> SysLog in the default desktop. Text based log files are not great for
> the average user and even for power users, the text-based log files
> don't distinguish errors from warnings or info messages.
GUIs for browsing any logs is a much wider issue than what we have here.
The primary source of information for diagnosing problems with the
printing system is the error_log. It has good discrimination indicators
for error, info etc. I believe Fedora feed it to journalctl so I suppose
you get colour too!
> >>> This is a symptom indicating you have done something to the system. It
> >>> never happened before; why should it happen now? Things don't generally
> >>> occur out of the blue.
> >>
> >> After looking more closely, I believe the root cause was a recent
> >> firewall change that was interfering with mDNS. Tweaking the firewall
> >> makes it work again. This hadn't been obvious because some other
> >> devices had been able to send stuff to the printer and the printer and
> >> the printer's web admin pages were accessible.
> >
> > Is it possible to be a little more specific about the firewall settings
> > which blocked mDNS packets? I think that on Fedora SELinux is there by
> > default and it is not unknown for it to cause a misconfiguration issue
> > such as the one you have experienced. However, I have not seen it on
> > Debian so knowing what you did would be a useful jumping off point for
> > documentation.
>
> In this case, Shorewall had been installed with a very basic configuration
>
> Adding this entry to /etc/shorewall/rules in SECTION NEW:
>
>
>
> SECTION NEW
>
> mDNS(ACCEPT) loc fw
>
>
>
> made it work.
Thank you for this; it gives me something to work on. Incidentally,
hp-setup GUI and hp-probe suggest examining firewall settings if a
printer is not detected.
Cheers,
Brian.
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