I'm trying to install a printer on a nearly-new copy of 20.04.3. If I access the graphic interface with VNC, the printer control panel is totally locked down, and will not allow me to unlock it. After smacking the cupsd.conf file around, I got it to give me the [expletive deleted] CUPS web interface, but every attempt to use that gets me "Forbidden" if I try to Modify or Add a printer. Trying to use lpadmin is equally useless.
It's a server, so access is remote.
I've tried uninstalling and reinstalling CUPS. No help. I found a post talking about some "apparmor" nonsense, so I installed the apparmor-util package and told it to not protect CUPS. No help. I have tried adding "Allow all" to just about every possible category in the cupsd.conf file. No help.
/var/log/cups/error_log:
E [02/Oct/2021:19:29:15 -0700] [Client 12] Returning HTTP Forbidden for CUPS-Get-Devices (no URI) from localhost
E [02/Oct/2021:19:29:15 -0700] [CGI] CUPS-Get-Devices request failed with status 401: Forbidden
/var/log/cups/access_log:
10.10.0.156 - boojum [02/Oct/2021:19:29:15 -0700] "POST /admin/ HTTP/1.1" 200 85 - -
localhost - - [02/Oct/2021:19:29:15 -0700] "POST / HTTP/1.1" 401 91 CUPS-Get-Devices successful-ok
localhost - boojum [02/Oct/2021:19:29:15 -0700] "POST / HTTP/1.1" 403 91 CUPS-Get-Devices successful-ok
10.10.0.156 - boojum [02/Oct/2021:19:29:15 -0700] "POST /admin/ HTTP/1.1" 200 1938 - -
/var/log/syslog:
Oct 2 19:27:36 bandersnatch kernel: [221.627776] audit: type=1400 audit(1633228056.968:105): apparmor="DENIED" operation="ptrace" profile="snap.docker.dockerd" pid=2482 comm="ps" requested_mask="read" denied_mask="read" peer="/usr/sbin/cupsd"
Note that the timestamp on the syslog entry is far too early to be plausibly connected to the other log entries. It looks like it might be something going on inside a docker instance.
