How to enable remote access to the Admin page in CUPS

cups

I'm looking to get access to the admin page of the CUPS web interface.

I can reach the page, and I can browse the majority of the site, but sadly the Admin page is still locked from remote sources.

I did set Allow from all and also tried Allow all everywhere now, and still I can't access the page.

What am I missing?

Config file

#
#
# Sample configuration file for the CUPS scheduler.  See "man cupsd.conf" for a
# complete description of this file.
#

# Log general information in error_log - change "warn" to "debug"
# for troubleshooting...
LogLevel warn

# Deactivate CUPS' internal logrotating, as we provide a better one, especially
# LogLevel debug2 gets usable now
MaxLogSize 0

# Allow connection from remote hosts
Port 631
Listen /var/run/cups/cups.sock

# Show shared printers on the local network.
Browsing On
BrowseOrder allow,deny
BrowseAllow all
BrowseLocalProtocols all

# Default authentication type, when authentication is required...
DefaultAuthType Basic

# Web interface setting...
WebInterface Yes

# Restrict access to the server...
<Location />
  Order allow,deny
  Allow from all
</Location>

# Restrict access to the admin pages...
<Location /admin>
  Order allow,deny
  Allow from all
</Location>

# Restrict access to configuration files...
<Location /admin/conf>
  AuthType Default
  Order allow,deny
  Allow from all
</Location>

# Set the default printer/job policies...
<Policy default>
  # Job/subscription privacy...
  JobPrivateAccess default
  JobPrivateValues default
  SubscriptionPrivateAccess default
  SubscriptionPrivateValues default

  # Job-related operations must be done by the owner or an administrator...
  <Limit Create-Job Print-Job Print-URI Validate-Job>
    Order deny,allow
    Allow from all
  </Limit>

  <Limit Send-Document Send-URI Hold-Job Release-Job Restart-Job Purge-Jobs Set-Job-Attributes Create-Job-Subscription Renew-Subscription Cancel-Subscription Get-Notifications Reprocess-Job Cancel-Current-Job Suspend-Current-Job Resume-Job Cancel-My-Jobs Close-Job CUPS-Move-Job CUPS-Get-Document>
    Require user @OWNER @SYSTEM
    Order deny,allow
    Allow from all
  </Limit>

  # All administration operations require an administrator to authenticate...
  <Limit CUPS-Add-Modify-Printer CUPS-Delete-Printer CUPS-Add-Modify-Class CUPS-Delete-Class CUPS-Set-Default CUPS-Get-Devices>
    AuthType Default
    Require user @SYSTEM
    Order deny,allow
    Allow from all
  </Limit>

  # All printer operations require a printer operator to authenticate...
  <Limit Pause-Printer Resume-Printer Enable-Printer Disable-Printer Pause-Printer-After-Current-Job Hold-New-Jobs Release-Held-New-Jobs Deactivate-Printer Activate-Printer Restart-Printer Shutdown-Printer Startup-Printer Promote-Job Schedule-Job-After Cancel-Jobs CUPS-Accept-Jobs CUPS-Reject-Jobs>
    AuthType Default
    Require user @SYSTEM
    Order deny,allow
    Allow from all
  </Limit>

  # Only the owner or an administrator can cancel or authenticate a job...
  <Limit Cancel-Job CUPS-Authenticate-Job>
    Require user @OWNER @SYSTEM
    Order deny,allow
    Allow from all
  </Limit>

  <Limit All>
    Order deny,allow
    Allow from all
  </Limit>
</Policy>

# Set the authenticated printer/job policies...
<Policy authenticated>
  # Job/subscription privacy...
  JobPrivateAccess default
  JobPrivateValues default
  SubscriptionPrivateAccess default
  SubscriptionPrivateValues default

  # Job-related operations must be done by the owner or an administrator...
  <Limit Create-Job Print-Job Print-URI Validate-Job>
    AuthType Default
    Order deny,allow
    Allow from all
  </Limit>

  <Limit Send-Document Send-URI Hold-Job Release-Job Restart-Job Purge-Jobs Set-Job-Attributes Create-Job-Subscription Renew-Subscription Cancel-Subscription Get-Notifications Reprocess-Job Cancel-Current-Job Suspend-Current-Job Resume-Job Cancel-My-Jobs Close-Job CUPS-Move-Job CUPS-Get-Document>
    AuthType Default
    Require user @OWNER @SYSTEM
    Order deny,allow
    Allow from all
  </Limit>

  # All administration operations require an administrator to authenticate...
  <Limit CUPS-Add-Modify-Printer CUPS-Delete-Printer CUPS-Add-Modify-Class CUPS-Delete-Class CUPS-Set-Default>
    AuthType Default
    Require user @SYSTEM
    Order deny,allow
    Allow from all
  </Limit>

  # All printer operations require a printer operator to authenticate...
  <Limit Pause-Printer Resume-Printer Enable-Printer Disable-Printer Pause-Printer-After-Current-Job Hold-New-Jobs Release-Held-New-Jobs Deactivate-Printer Activate-Printer Restart-Printer Shutdown-Printer Startup-Printer Promote-Job Schedule-Job-After Cancel-Jobs CUPS-Accept-Jobs CUPS-Reject-Jobs>
    AuthType Default
    Require user @SYSTEM
    Order deny,allow
    Allow from all
  </Limit>

  # Only the owner or an administrator can cancel or authenticate a job...
  <Limit Cancel-Job CUPS-Authenticate-Job>
    AuthType Default
    Require user @OWNER @SYSTEM
    Order deny,allow
    Allow from all
  </Limit>

  <Limit All>
    Order deny,allow
    Allow from all
  </Limit>
</Policy>

Dockerfile

#
#   Add a Printer user
#
RUN useradd \
    --groups=sudo,lp,lpadmin \
    --create-home \
    --home-dir=/home/print \
    --shell=/bin/bash \
    print

#
#   Set the password for the printer user
#
RUN echo print:sdsds | chpasswd

Best Answer

What I would do is at the following block below the </Policy> tag:

<Location />
    Order allow,deny
    Allow localhost
    Allow from 192.168.0.*
    Allow from 10.0.*.*
</Location>

Listen 0.0.0.0:631

For admin access specifically, the vanilla config normally has:

<Location /admin/conf>
  AuthType Default
  Require user @SYSTEM
  Order allow,deny
</Location>

In order to create a suitable user account, you just need to create a user that is a member of the lpadmin group (I would recommend you do require some kind auth for the admin section): sudo useradd -g lpadmin cupsadmin, then set a password.

See also https://askubuntu.com/questions/387217/cups-admin-user-and-password-saucy

Update: The below should work as a starting point to also happens to fix the issue originally raise by @DavidGatti - it isn't as complete/granular as the original config, but the policy config can be re-added.

This config does however do away with using @SYSTEM user, and instead will accept any 'local', valid user. The use-case for the config is running CUPS in a docker container, so it seemed best to avoid requiring anything 'special', beyond a user with a password, to provide admin access to CUPS. 

# Disable cups internal logging - use logrotate instead
MaxLogSize 0

# Log general information in error_log - change "warn" to "debug"
# for troubleshooting...
LogLevel warn
#PageLogFormat

Listen /run/cups/cups.sock
Listen 0.0.0.0:631
Port 631

# Show shared printers on the local network.
Browsing On
BrowseLocalProtocols dnssd

# Default authentication type, when authentication is required...
DefaultAuthType Basic

# Web interface setting...
WebInterface Yes

# Restrict access to the server...
# This config allow anyone access to the WUI
<Location />
  Order allow,deny
  Allow all
</Location>

# Restrict access to the admin pages...
# Allows anyone to try and access admin pages.
# Any local user's credentials will be accepted
<Location /admin>
  AuthType Basic
  Require valid-user
  Allow all
  Order allow,deny
</Location>

# Restrict access to configuration files...
# Any local user's credentials will be accepted
<Location /admin/conf>
  AuthType Basic
  Require valid-user
  Allow all
  Order allow,deny
</Location>

# Restrict access to log files...
# Any local user's credentials will be accepted
<Location /admin/log>
  AuthType Basic
  Require valid-user
  Allow all
  Order allow,deny
</Location>

Browsing On

You might also find some decent pointers in How to configure cups to allow remote printing with authentication and local printing without?

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