It took me a little while to figure out how to get a machine running Windows 7 to print to a remote CUPS printer so I thought I’d document what I did in case it helps others (as well as myself as I am sure I will forget this if I don’t document it)…

The first step is to go to the “Devices and Printers” control panel. There one has to click on the “Add Printer” link at the top (also available in the right-click menu).

In the dialog window that follows, select “Add a network, wireless, or Bluetooth printer”. Windows will then try to automatically find an available network printer. At that point I stop the search by clicking on the “Stop” button, and the click on “The printer that I want isn’t listed”.

In the next dialog, “Find a printer by name or TCP/IP address”, select the option “Select a shared printer by name”, and enter an URL like the following:

http://<IP address or hostname of the CUPS server>:631/printers/<Name of the CUPS printer queue>

Then click “Next”.

The next step is important — it’s where a printer driver must be selected. Normally, the CUPS server knows what printer it has connected. In that case on needs to send print jobs in a format that the CUPS server can understand, like Postscript or PDF — the CUPS server will convert to the appropriate language understood by the printer. However, it might be the case that the CUPS server has a raw queue, in which case the CUPS client must sent the print job in the format that the printer can understand.

So, when selecting a driver in the Windows “Add Printer Wizard”, one can do the folowing:

1. If not using a raw queue on the CUPS server, select the “Generic” manufacturer, and then the “MS Publisher Color Printer”. This will cause the print job to be of type “application/postscript”, which CUPS can then convert to the right printer language.
2. If using a raw queue on the CUPS server then select the appropriate printer driver so the Windows client sends the job in the format that the printer can understand.

References

• As always, the Arch Linux wiki has great information. Specifically, the Sharing via IPP section of the CUPS/Printer sharing page contains some key information:

“[…] install the native printer drivers for your printer on the Windows computer. If the CUPS server is set up to use its own printer drivers, then you can just select a generic postscript printer for the Windows client(e.g. ‘HP Color LaserJet 8500 PS’ or ‘Xerox DocuTech 135 PS2’).”

Note that I didn’t have luck using the “HP Color LaserJet 8500 PS” printer driver — it would generate a printer job in the “PJL encapsulated PostScript document text” format, which CUPS would have problems handling. But the “MS Publisher Color Printer” worked fine.

• This page contains good information on how to create a CUPS raw printer queue:

http://opennomad.com/content/raw-cups-configuration-challenge

The machine running our CUPS print server at home recently had to be replaced by another one. Today we had to set up a new CUPS client to print to the CUPS server running on the new machine.

It turns out it was not an easy experience — the CUPS client kept saying “Bad Request” and there was nothing in the CUPS log files on the server side. We then realized that we were logging at a level that could be hiding important messages, based on this parameter in /etc/cups/cupsd.conf:

LogLevel warn

Changing this parameter to:

LogLevel debug

and trying again to print or modify the printer produced the following messages in /var/log/cups/error.log:

D [04/Dec/2016:16:30:58 -0500] [Client 1] GET /printers/HP_Officejet_2620_series.ppd HTTP/1.1
D [04/Dec/2016:16:30:58 -0500] cupsdSetBusyState: newbusy="Active clients and dirty files", busy="Dirty files"
D [04/Dec/2016:16:30:58 -0500] [Client 1] Read: status=200
D [04/Dec/2016:16:30:58 -0500] [Client 1] No authentication data provided.
E [04/Dec/2016:16:30:58 -0500] [Client 1] Request from "[v1.2003:1480:eca5:1120:7e7a:91ff:febf:d3b2]" using invalid Host: field "printer.example.com:631".
D [04/Dec/2016:16:30:58 -0500] [Client 1] cupsdSendHeader: code=400, type="text/html", auth_type=0
D [04/Dec/2016:16:30:58 -0500] [Client 1] Closing because Keep-Alive is disabled.
D [04/Dec/2016:16:30:58 -0500] [Client 1] Closing connection.

Aha! ‘Request from “[v1.2003:1480:eca5:1120:7e7a:91ff:febf:d3b2]” using invalid Host: field’!

Now with an actual error message to search for I was able to find Debian bug #530027, which has as a “workaround” to set “ServerAlias *” in /etc/cups/cupsd.conf.

After making that change and reloading CUPS things started to work. Note that the root cause of the problem is that the hostname of the print server changed, and the CUPS client was using the hostname of the old server via a DNS CNAME.

Beats me why such an error message is not produced unless the CUPS logging level is set to “debug”.

I keep getting bitten by this issue every time I set up a new printer on a new machine to print to a remote CUPS server that has the physical printer connected to it (via USB, for example), and every time I run into the same problem it takes me a little while until I remember what the probblem is. So, I have decided to document the problem (and the solution) for next time I run in the problem.

The printer is correctly configured on the server, and by “correctly configured” I mean that the printer is using the correct driver, and that printing is working, both locally on the machine with the attached printer, and remotely on other clients.

On the client side, the URI for the printer is correct; for example ipp://servername.example.com:631/printers/printer_name. Everything seems fine until a document is sent to the printer on the client — when this happens, the server’s cupsd (not the client’s), generates runs into a problem and nothing gets printed. The server’s cupsd error file (typically /var/log/cups/error_log) contains something like this:

D [16/Oct/2016:21:25:45 -0400] [Job 2] Queued on "HP_Officejet_2620_series" by "username".
 D [16/Oct/2016:21:25:45 -0400] [Job 2] File of type application/vnd.cups-raster queued by "username".
 D [16/Oct/2016:21:25:45 -0400] [Job 2] Adding end banner page "none".
 D [16/Oct/2016:21:25:45 -0400] [Job 2] time-at-processing=1476667545
 D [16/Oct/2016:21:25:45 -0400] [Job 2] 1 filters for job:
 D [16/Oct/2016:21:25:45 -0400] [Job 2] hpcups (application/vnd.cups-raster to printer/HP_Officejet_2620_series, cost 0)
 D [16/Oct/2016:21:25:45 -0400] [Job 2] job-sheets=none,none
 D [16/Oct/2016:21:25:45 -0400] [Job 2] argv[0]="HP_Officejet_2620_series"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] argv[1]="2"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] argv[2]="username"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] argv[3]="Untitled Document 1"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] argv[4]="1"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] argv[5]="job-uuid=urn:uuid:09c01fb4-c9b4-39de-6e4c-3d33a0710d25 job-originating-host-name=[v1.2002:4170:e35:1:81ae:ffff:ffff:83a7] date-time-at-creation= date-time-at-processing= time-at-creation=1476667545 time-at-processing=1476667545"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] argv[6]="/var/spool/cups/d00002-001"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[0]="CUPS_CACHEDIR=/var/cache/cups"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[1]="CUPS_DATADIR=/usr/share/cups"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[2]="CUPS_DOCROOT=/usr/share/cups/doc"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[3]="CUPS_FONTPATH=/usr/share/cups/fonts"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[4]="CUPS_REQUESTROOT=/var/spool/cups"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[5]="CUPS_SERVERBIN=/usr/lib/cups"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[6]="CUPS_SERVERROOT=/eD [16/Oct/2016:21:25:45 -0400] [Job 2] envp[26]="PRINTER=HP_Officejet_2620_series"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[27]="PRINTER_STATE_REASONS=none"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[28]="CUPS_FILETYPE=document"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[29]="FINAL_CONTENT_TYPE=printer/HP_Officejet_2620_series"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[30]="AUTH_I****"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] Started filter /usr/lib/cups/filter/hpcups (PID 5259)
 D [16/Oct/2016:21:25:45 -0400] [Job 2] Started backend /usr/lib/cups/backend/hp (PID 5260)
 D [16/Oct/2016:21:25:45 -0400] [Job 2] PID 5259 (/usr/lib/cups/filter/hpcups) stopped with status 1.
 D [16/Oct/2016:21:25:45 -0400] [Job 2] Hint: Try setting the LogLevel to "debug" to find out more.
 D [16/Oct/2016:21:25:45 -0400] [Job 2] PID 5260 (/usr/lib/cups/backend/hp) exited with no errors.
 D [16/Oct/2016:21:25:45 -0400] [Job 2] prnt/hpcups/HPCupsFilter.cpp 565: cupsRasterOpen failed, fd = 6
 D [16/Oct/2016:21:25:45 -0400] [Job 2] prnt/backend/hp.c 919: ERROR: null print job total=0
 D [16/Oct/2016:21:25:45 -0400] [Job 2] End of messages
 D [16/Oct/2016:21:25:45 -0400] [Job 2] printer-state=3(idle)
 D [16/Oct/2016:21:25:45 -0400] [Job 2] printer-state-message="Filter failed"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] printer-state-reasons=none
 tc/cups"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[7]="CUPS_STATEDIR=/run/cups"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[8]="HOME=/var/spool/cups/tmp"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[9]="PATH=/usr/lib/cups/filter:/usr/bin:/usr/bin:/bin:/usr/bin"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[10]="SERVER_ADMIN=root@server.example.com"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[11]="SOFTWARE=CUPS/2.2.1"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[12]="TMPDIR=/var/spool/cups/tmp"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[13]="USER=root"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[14]="CUPS_MAX_MESSAGE=2047"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[15]="CUPS_SERVER=/run/cups/cups.sock"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[16]="CUPS_ENCRYPTION=IfRequested"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[17]="IPP_PORT=631"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[18]="CHARSET=utf-8"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[19]="LANG=en_US.UTF-8"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[20]="PPD=/etc/cups/ppd/HP_Officejet_2620_series.ppd"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[21]="RIP_MAX_CACHE=128m"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[22]="CONTENT_TYPE=application/vnd.cups-raster"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[23]="DEVICE_URI=hp:/usb/Officejet_2620_series?serial=CN4654G2BG0600"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[24]="PRINTER_INFO=HP Officejet 2620 series"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[25]="PRINTER_LOCATION=My desk"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[26]="PRINTER=HP_Officejet_2620_series"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[27]="PRINTER_STATE_REASONS=none"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[28]="CUPS_FILETYPE=document"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[29]="FINAL_CONTENT_TYPE=printer/HP_Officejet_2620_series"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] envp[30]="AUTH_I****"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] Started filter /usr/lib/cups/filter/hpcups (PID 5259)
 D [16/Oct/2016:21:25:45 -0400] [Job 2] Started backend /usr/lib/cups/backend/hp (PID 5260)
 D [16/Oct/2016:21:25:45 -0400] [Job 2] PID 5259 (/usr/lib/cups/filter/hpcups) stopped with status 1.
 D [16/Oct/2016:21:25:45 -0400] [Job 2] Hint: Try setting the LogLevel to "debug" to find out more.
 D [16/Oct/2016:21:25:45 -0400] [Job 2] PID 5260 (/usr/lib/cups/backend/hp) exited with no errors.
 D [16/Oct/2016:21:25:45 -0400] [Job 2] prnt/hpcups/HPCupsFilter.cpp 565: cupsRasterOpen failed, fd = 6
 D [16/Oct/2016:21:25:45 -0400] [Job 2] prnt/backend/hp.c 919: ERROR: null print job total=0
 D [16/Oct/2016:21:25:45 -0400] [Job 2] End of messages
 D [16/Oct/2016:21:25:45 -0400] [Job 2] printer-state=3(idle)
 D [16/Oct/2016:21:25:45 -0400] [Job 2] printer-state-message="Filter failed"
 D [16/Oct/2016:21:25:45 -0400] [Job 2] printer-state-reasons=none

The problem is that “Filter failed”, and my understanding of the root cause of the problem is that the printer is configured on the client with the correct make and model for the printer that is physically connected to the server. So, if the printer is, for example, an Hewlett-Packard printer, the client will render the print job and send to the server the rendered job. The server is expecting the job in some other format (Postscript? PDF? It’s not important) and when it receives it in rendered format, for the exact printer make and model, then the filter on the server fails to render the print job.

The solution is to configure the printer on the client as a “raw” printer, i.e. a printer where the printer driver is not specified. This way the client sends the job “unrendered” and lets the server do the rendering according to the correct printer driver that is installed (on the server).

I remember that when I first ran into this problem it was not easy to figure out what was wrong. I enabled all the debugging knobs that I could find and nothing helped. It probably was some post to some random blog or Internet forum what gave me a clue, but it was not easy to find.

And to add insult to injury, using the Printer control panel on Ubuntu to modify the default settings of a printer (on a CUPS client), would change the local printer configuration from “raw” to a specific make and model, which would then trigger the problem explained above. This made me scratch my head and waste hours trying to get a previously working printer that stopped working to working state again.

Ggggrrrrr.

References

This RedHat bug report has good information on the issue and how clients and servers should be configured:

https://bugzilla cialis 5mg preis.redhat.com/show_bug.cgi?id=1010580

This ArchLinux forum discussion is very relevant to the problem:

https://bbs.archlinux.org/viewtopic.php?pid=1589908#p1589908

Finally, this ArchLinux wiki page:

https://wiki.archlinux.org/index.php/CUPS#Network_2

contains the following note, which describes precisely what the issue is:

“Warning: Avoid configuring both the server and the client with a printer filter – either the print queue on the client or the server should be ‘raw’. This avoids sending a print job through the filters for a printer twice, which can cause problems (for instance, [3]). See #Usage for an example of setting a print queue to ‘raw’.”