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Cups "add printer" page returns forbidden on Web Interface on http://localhost:631/admin

I tried adding my main user to "lp" and restarting, but no change. I also tried setting at the top of the cups.conf SystemGroup printadmin and doing sudo systemctl restart cups to no avail.

Here is the relevant cups.conf

# Restrict access to configuration files...
<Location /admin/conf>
  AuthType Default
  Require user @SYSTEM
  Order allow,deny
</Location>

I'm just trying to add a printer using the web interface, but something about the permissions doesn't allow my user credentials to work. There is no group named SYSTEM or lpadmin.

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1
  • It's not obvious to me from the question, but it sounds like you have a web interface for cups and it's not working? Two ideas jump to mind -- that the HTTP server user (that's running the interface) does not have permission; the other is that there's an HTTP permission issue (or misconfiguration) that's preventing the interface from running/doing something. Could you expand on your question to clarify what you're doing?
    – Jeff Schaller ♦
    Oct 11, 2015 at 23:46

4 Answers 4

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34

I had to combine two other answers for Ubuntu, and the solution is to add myself to the lpadmin group:

sudo usermod -a -G lpadmin your-username

For every system, the solution should be:

  • Open the file /etc/cups/cups-files.conf.
  • Find the group name at the line containing SystemGroup.
  • Add yourself to that group (command above) and apply it (reboot for example).
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  • 1
    No need to reboot, sudo systemctl restart cups like mentioned in another answer was enough.
    – baptx
    Jul 21 at 16:56
21

Update: On Fedora 25 this is now default... So if you're having this problem on Fedora 25+, you likely messed up your config or you have a different problem. But this might still be useful users of old installs of CentOS/RHEL... you should not be using Fedora 24 at this point.

Find /etc/cups/cups-files.conf as root. Look for the line with SystemGroup sys root add wheel to it.

The following two liner should do it for you on Fedora 24

 sudo sed -i '/SystemGroup sys root$/ s/$/ wheel/' /etc/cups/cups-files.conf
 sudo systemctl restart cups
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  • 1
    Fedora 24 is still a supported release until sometime in the summer of 2017. So, while I too recommend upgrading, it's okay that not everyone has yet. :)
    – mattdm
    Jan 14, 2017 at 14:23
  • 1
    In debian the wheel group isn't use. If you use Debian/Ubuntu add sudo to the list instead.
    – Guy
    Aug 5, 2020 at 8:31
  • the wheel was already there for me on Arch. Just needed to add myself to that group using sudo usermod -a -G wheel $USER
    – walnut_salami
    May 30, 2021 at 5:39
10

The solution is

sudo usermod -a -G sys YourUser

I wrote a more detailed article on how to debug such issues.

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  • 8
    It's a bit of a sledgehammer to add yourself to the system group, which may grant your user/processes more power than you'd expect. See my answer for a good alternative grants you access to cups alone.
    – Ray Foss
    Jul 8, 2016 at 14:48
  • 4
    Eek - don't do this if you're setting it up for anyone other than yourself.. in your own home.. Can't use this solution as I'm setting up printing for a whole business, I don't want to give my users god-powers on the device.
    – Dagrooms
    Jun 13, 2017 at 19:03
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    On a Debian-based OS this answer is valid if you use the group lpadmin.
    – Anthony
    Jul 29, 2019 at 13:50
0

I have cups installed in OMV5/Docker/Portainer and in the settings file only users in lpadmin group can add printers, so the solution (at least in this particular case) is to add your user to that group or add your user group to the config file. You can check the required group in /etc/cups/cups-files.conf and if it turns out its the same as me just run.

usermod -a -G lpadmin yourusername

on the other hand if you're using the same configuration as I am, users in OMV and portainer wont migrate to cups so you'll have to create them(it) 1st:

adduser yourusername
usermod -aG sudo yourusername

and only then:

usermod -a -G lpadmin yourusername
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