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| README.md | ||
CUPS Printing README
CUPS (also known as the "Common UNIX Printing System") is the standards-based, open source printing system for Linux and macOS.
It allows your Internet-in-a-Box (IIAB) to act as a print server.
This can be useful if a printer is attached to your IIAB — so student/teacher print jobs from client computers and phones can be processed — and then sent to the appropriate printer.
Web Administration
Please administer CUPS at http://box/print using:
- Username:
Admin - Password:
changeme
Or use any Linux user that is a member of the Linux group: lpadmin
Security
The above uses 'SystemGroup lpadmin' in /etc/cups/cups-files.conf — in coordination with about 15 '@SYSTEM' lines and 'DefaultAuthType Basic' in /etc/cups/cupsd.conf
CUPS creates a 10-year (unsigned) HTTPS certificate during installation, that will be very confusing to non-technical users when they log in, as a result of modern browser warnings.
How it Works
Understand how IIAB configures CUPS for all IP addresses and all hostnames (IIAB redirects around the "since 2009" CUPS problem mentioned below!) by reading these in-line explanations:
Modify these 2 files at your own risk:
- /etc/cups/cupsd.conf (run
sudo cupsctlandsudo cupsd -tto verify the file!) - /etc/nginx/conf.d/cups.conf
If you make modifications to the above files, don't forget to restart systemd services: (run this as root)
systemctl restart cups cups-browsed nginx
Troubleshooting
http://localhost:631 is very useful if NGINX redirects or CUPS permissions are set wrong.
Beware that http://box:631 and http://box.lan:631 will not work, due to a known issue with CUPS since 2009.
Run ps aux | grep cups and systemctl status cups to verify the CUPS systemd service is running well.
Finally, keep an eye on /var/log/cups/error_log to be sure.