Translation(s): none


Driverless printing with CUPS. Requires at least CUPS 2.2.2 and version 1.13.0 of cups-filters. Debian 10 (buster) and later installations meet both these conditions. The advice here (an ethernet or wireless connection) and here (a USB connection) could get your modern IPP printer going with little effort.

Introduction

Driverless printing requires a modern printer. A user can be assured of having such a device when it is network-capable and it is

A Mopria-certified device calls for PWG raster, PCLm or PDF to be available as a PDL. However, it is observed that all PCLm, PWG raster or PDF printers also support Apple raster. Therefore, AirPrint-capability is a sufficient criterion regarding whether a printer can be operated driverlessly on Debian. Just look for AirPrint on the box or in the literature.

It would be unusual for a network printer not to provide a USB connection too. In that case, the printer would almost certainly offer the IPP-over-USB protocol if it has been manufactured after mid-2012.

Debian 11 (bullseye) is geared up to auto-setup network and USB print queues with cups-browsed. Should auto-set fail and debugging cups-browsed is an unattactive proposition or there is a more complex situation to resolve, a manual queue setup with lpadmin, the CUPS web interface or system-config-printer is recommended.

Driverless printing for CUPS and cups-filters is here to stay. While it will be sone time before CUPS 3.0 enters a stable Debian distribution, an interested user may want to become aware of changes planned by the CUPS and cups-filters developers.

The Concept of Driverless Printing

Driverless printing is targeted at the client side of printing and refers to the ability of the client device (computer, smartphone, tablet, laptop etc) to print without having to install any static capability files or drivers (manufacturer-specific or otherwise) on the client.

There exist a variety of methods for a client to submit a job to a printing system and print driverlessly:

This page is intended to highlight and explain driverless printing in the context of directly communicating with a printer using packages provided by Debian, so not all these methods will receive attention here. Furthermore, details for using iOS and Android mobile clients are not treated.

Remember that CUPS can act as a client or server. In its server capacity it can emulate an IPP Everywhere or Apple AirPrint printer. However, the focus here is on CUPS as a client connecting to a printer that offers driverless printing functions.

Driverless Printing and Printers

A traditional printing system based on CUPS, cups-filters and cups-browsed generally obtains information about printer features and capabilities from what is stored in a static capability file such as a PostScript Printer Description (PPD) file. This static file is stored on the client device (desktop computer, laptop, tablet etc) itself. If the PPD on the client requires the sending of a job using a non-standardised Page Description Language (PDL), a driver would be required for converting to the printer-specific PDL and that driver too would have to be on the client. A client that regularly connected to different printers would have to maintain static capability files and drivers for each printer.

This is not seen as an acceptable situation, especially for mobile clients, which may have limited storage for PPDs and drivers and that may lack resources, such as battery power. Neither is it deemed particularly realistic for a user to have to set up or reconfigure a laptop computer or mobile device for each printer that is encountered. This requires a level of expertise and a time and effort commitment that cannot be assumed to be possessed.

Then contrast the printer situation with the behaviour of other peripherals like keyboards, mice, cameras and USB mass storage. Plug such devices in and they are immediately and reliably there to be used. The objective is to have printing no less available when a printer is detected.

The response of printer manufacturers to the desire for driverless printing has been to enhance their printers in the following way:

Note again that we are talking here about sending a job directly to a printer, not to a print queue being advertised by CUPS.

PDLs for Driverless Printing

Two raster formats, Apple raster and PWG raster, have been developed to implement driverless printing.

In the case of PWG raster the raster format was chosen because it is a simpler format than that of the high-level languages, which also require significant resources on the printer. Printer-embedded PostScript interpreters can be buggy and/or slow and PostScript also has the disadvantage that it makes interoperability between client and printer difficult because PostScript does not fit cleanly with the IPP and PWG models. Streaming was chosen to send a job to a printer rather than generating a file that is downloaded and then printed. This way large jobs don't take up too much memory or storage space on the printer and printing commences with minimum delay.

CUPS: PWG and Apple Raster

The abilitity to create Apple raster files has been added to the existing PWG raster support in CUPS and made its appearance in CUPS 2.2.2; this enhancement was soon applied in version 1.13.0 of cups-filters and cups-browsed. Complete support for IPP Everywhere printers was already in Debian, so, with CUPS 2.2.2, AirPrint printers joined the class of printers that will work driverless with Debian.

With the incorporation of the two raster formats as a PDL in CUPS, IPP 2.0 to allow for querying the capabilities information from the printer and Bonjour/DNS-SD to find the printers in the network, Debian has everything needed for driverless printing to an IPP printer.

The processing of a job to create an Apple raster file is taken care of by CUPS' rastertopwg filter. The file produced by the filter is sent directly to the printer with IPP, so no vendor-specific filters are involved. This opens up the possibility of avoiding the use of non-free drivers on the CUPS client or server used for printing.

The CUPS PPD Generator

To support driverless printing fully, CUPS has a PPD generator that will drive a traditional CUPS print queue. The generator queries the printer and creates the necessary PPD options and values needed to support Apple Raster, PWG Raster, JPEG, and PDF printing. A CUPS generated PPD uses the everywhere model and can be identified from the *PCFileName "ippeve.ppd" line in the PPD.

                                     ->|--------------------------------------------> Printer
text -> texttopdf -> pdftopdf -> PDF ->| gstoraster -> rastertopwg -> PWG raster ---> Printer
                                     ->| gstoraster -> rastertopwg -> Apple raster -> Printer

The cups-filters PPD Generator

This generator uses the driverless utility and is basically a copy of the PPD generator from CUPS that has been put into the libcupsfilters library. It is kept in sync with the original by incorporating any changes to the original. A libcupsfilters generated PPD can be identified from the *PCFileName "drvless.ppd" line in the PPD.

Although the cups-filters PPD generator is kept closely in step with the CUPS one, the two are not identical:

text -> texttopdf -> pdftopdf -> PDF -> gstoraster -> rastertopclm -> PCLm ---> Printer

Creating a Driverless Print Queue with lpadmin (Short Version)

Obtain the URI of a printer:

driverless

Set up the print queue (uses the CUPS PPD generator):

lpadmin -p <print_queue_name> -v <URI> -E -m everywhere

Set up the print queue (uses the cups-filters PPD generator):

lpadmin -p <print_queue_name> -v <URI> -E -m driverless:<URI>

Creating a Driverless Print Queue with lpadmin

Some familiarity with a device-uri is assumed in this section.

With a single AirPrint printer on the network a partial output from /usr/sbin/lpinfo -v could be:

network dnssd://HP%20ENVY%204500%20series%20%5BFAFAC2%5D._ipp._tcp.local/?uuid=1c852a4d-b800-1f08-abcd-308d99fafac2
network socket://192.168.7.235:9100
network ipp://envy4500.local:631/ipp/print

The snmp backend has found the printer will accept jobs on port 9100 (socket://192...). CUPS will not set up an everywhere queue using this URI because it is unable to query the printer with it.

The ENVY 4500 has also been discovered from the printer's Bonjour broadcasts using the dnssd and ipp backends. Both these URIs are equally stable and can be used for driverless printing, with a dnssd URI being preferred if the ipp URI is using a numeric IP address.

The device-uri for the printer can also be found with the ippfind or driverless utilities. ippfind locates DNS-SD advertised printers and queues. driverless (a cups-filters utility) lists IPP printers only.

ippfind                         (Shows IPP printers and print queues).
ippfind -T 5                    (Possibly more reliable).
ippfind ! --txt printer-type    (Show IPP printers only).

driverless                  (To get the device-uri).
driverless list             (For the device-uri and printer metadata).
driverless <device-uri>     (Generate a PPD for the printer at <device-uri>).

A queue for driverless printing from a client is now set up with

lpadmin -p <print_queue_name> -v <device-uri> -E -m everywhere

The everywhere model causes the printer referred to by the -v option to be queried. A list of printer capabilities is returned and a PPD is automatically generated by CUPS for use by command line programs and applications.

It may be preferred to have the PPD generated by cups-filters, so first find the driver URI (driverless:ipp://...) with

driverless list

and create the queue with

lpadmin -p <print_queue_name> -v <device-uri> -E -m <driver URI>

If the -v option is the URI of a queue on a remote CUPS server, this technique can create a driverless queue on the client for a remote non-raw queue. This is the method employed when CUPS sets up a temporary queue on a client.

Creating a Driverless Print Queue with the CUPS Web Interface

Some familiarity with the CUPS web interface is assumed in this section.

Creating a Driverless Print Queue with system-config-printer

Some familiarity with system-config-printer is assumed in this section.

Creating a Driverless Print Queue with cups-browsed (Short Version)

Edit /etc/cups/cups-browsed.conf to uncomment the directive below:

CreateIPPPrinterQueues All

Restart cups-browsed:

systemctl restart cups-browsed

cups-browsed version 1.27.1 changed the default for CreateIPPPrinterQueues to All. Considering that cups-browsed is a recommended package for cups-daemon, this change should lead to making IPP printers immediately visible and available on a bullseye installation.

Creating a Driverless Print Queue with cups-browsed

This method leads to discovery of an AirPrint or IPP Everywhere printer and the automatic set up of a print queue with lpadmin. A PPD for the queue is created using the cups-filters PPD generator. The CUPS PPD generator may be used instead; see the UseCUPSGeneratedPPDs directive in the cups-browsed.conf manual. The PPD is used to display printer options for command line programs and in applications. There are just two operations a user has to carry out:

CreateIPPPrinterQueues All
CreateIPPPrinterQueues Driverless

systemctl restart cups-browsed

cups-browsed version 1.27.1 changed the default for CreateIPPPrinterQueues to All. Considering that cups-browsed is a recommended package for cups-daemon, this change should lead to making IPP printers immediately visible and available on a bullseye installation.

lpstat -t
lpoptions -p <queue_name> -l

IPP-over-USB: The Basics

The previous methods to set up driverless printing with CUPS are presented in the context of a network-only connection (wireless or ethernet). They require the Internet Printing Protocol (IPP) for querying the capabilities of the printer so that the PPD can be generated. They also need IPP to send option settings to the printer (as IPP attributes).

Fortunately, driverless printing is not confined to the network only but also works in exactly the same way via USB using the IPP-over-USB daemon, ipp-usb. ipp-usb serves for using the device via USB; this is fully independent of whether there is also a network connection available between the computer and the printer. A recent AirPrint printer should support IPP-over-USB. The support situation regarding USB-only post-2012 printers has yet to be completely clarified, but it is known that such devices are not guaranteed to understand the protocol.

The IPP USB specification describes an extension to USB that defines a standard for making IPP available over a USB Print class interface, and is intended to allow USB connected devices to achieve functional parity with network connected devices using IPP. In other words, whatever can be done over a network connection may also be done over a USB connection. A USB connected printer is therefore seen as a network printer when IPP-over-USB is used.

The previous sentence indicates that users employing the CUPS web interface or system-config-printer should be looking under network printers to establish a connection with the printer.See SystemPrinting for more detail.

It should be straightforward and reliable to use a printer or multi-function device via ethernet or WiFi and, in general, this is the recommended type of connection to employ. Also, such network connections allow easy sharing of the device. Some reasons why a user may want or have a preference for a USB connected MFD or printer are:

Whether a printer can use IPP-over-USB may be determined by executing lsusb -v|less and searching for the lines containing bInterfaceClass.*7. A bInterfaceProtocol line should be found a few lines below each bInterfaceClass line.

Alternatively, execute

lsusb -v | grep -A 3 bInterfaceClass.*7

A value of 4 for bInterfaceProtocol indicates a USB IPP device.

IPP-over-USB: Automatic Discovery and Setup

Beginning with version 2.3.3-2 the cups-daemon package installs ipp-usb as a recommended package. When an IPP-over-USB device is connected to the computer, systemd will use /lib/systemd/system/ipp-usb.service to start the daemon. cups-browsed is also installed by default, so, because the USB connected printer emulates a network printer, it will auto-create a driverless print queue for the printer.

Note that IPP-over-USB reserves the USB interface connection with the printer/scanner exclusively for itself and communication with a printer/scanner device by software that does not operate using the IPP-over-USB protocol becomes impossible while ipp-usb is running. This is a consequence of the design of USB communication. It is not a bug in ipp-usb.

  • For example, a print queue for an HP MFD can be set up with a vendor driver and PPD, but printing to it will not take place because the software does not use the IPP-over-USB protocol. The same holds true for all other drivers, free or non-free. Only driverless print queues will work with IPP-over-USB. It would be as well to remove existing queues based on vendor drivers to avoid the appearance of non-working queues in print dialogs. Removing vendor packages (free or non-free) from the system is also something to consider.

Communicating with a USB connected scanner via classic SANE backends such as libsane-hpaio, sane-pixma or sane-epson2 also becomes impossible with the ipp-usb daemon active and running.

  • Expecting the non-free Brother and Samsung backends to work would also be unreasonable. Only driverless backends will work with IPP-over-USB. A good solution to have reliable scanning with IPP is to install the independent SANE backend, sane-airscan, in addition to the official SANE backend,sane-escl, that comes with libsane1. sane-airscan is a highly regarded backend that interworks with IPP-over-USB very well. A non-working SANE backend may be made invisible to a frontend by commenting out the appropriate entry in /etc/sane.d/dll.conf or /etc/sane.d/dll.d.

An important idea underlying IPP-over-USB is having the ability to expose the local USB-connected printer only to localhost and not to the entire local network. This condition is fulfilled by using at least version 0.8-1 of avahi-daemon.

IPP-over-USB: Investigation and Troubleshooting

Remember, although the actual physical connection is a USB one, the device has effectively become a networked device advertised on localhost by default, not to the local network. All the usual network commands may be used in addition to the CUPS commands.

systemctl list-units "ipp-usb*" | grep service
systemctl status ipp-usb

=     lo IPv4 ENVY4500 (USB)  Internet Printer        local
hostname = [desktop.local]
address = [127.0.0.1]
port = [60000]

http://127.0.0.1:60000
http://desktop.local:60000

driverless

lpadmin -p <chosen_printer_name> -v <URI> -m everywhere
lpadmin -p <chosen_printer_name> -v <URI> -m driverless:<URI>

ENVY4500_USB_ network none ipp://ENVY4500%20(USB)._ipp._tcp.local/
envy4500usb permanent ipp://localhost/printers/envy4500usb ipp://ENVY4500%20(USB)._ipp._tcp.local/

lpoptions -p <destination> -l

CUPS 2.2.4 and Driverless Printing

CUPS' ability directly to browse the DNS-SD (Bonjour) broadcasts of remote print queues and printers, previously absent, was introduced in CUPS 2.2.4. This means that a system with CUPS 2.2.4 or later, such as Debian 10 (Buster), will display remote queues and IPP printers with lpstat -e and in the print dialogs of some applications without cups-browsed, needed on Debian 8 (Jessie) and Debian 9 (stretch) for remote queue management, being on the system. No action on the part of the user is required.

Essentially, CUPS uses its CupsGetDests and CupsEnumDests functions to discover shared queues and IPP printers on the local network that can be printed to and makes them available for display in an application. Whether or not the application displays them depends on the chosen application. Printing to an enumerated entry leads to the formation of a temporary queue. A temporary queue is intended to last for a minute only.

CUPS 2.2.4 and the GTK Print Dialog

The print dialog of GTK applications such as firefox and evince does not function in the same way as the Qt and Libreoffice dialogs. It obtains queue and printer information directly from DNS-SD broadcasts and not through CUPS, so it has no knowledge of what CUPS 2.2.4 and later are capable of doing. Basically, except for local queues, CUPS is unneeded. It may as well not be on the system.

In addition, using the GTK print dialog always results in the production of a PDF. Printers that that do not have PDF as an acceptable PDL will not process such a print job.

This leads to the following problem.

CreateRemoteCUPSPrinterQueues No

Managing queues and printers in the GTK dialog with the first solution also leads to the other dialogs adopting cups-browsed as the queue and printer management application.

Duplicate Print Queues

The entries shown in the print dialogs of applications are the names of existing or potential print queues. The existing queues have been set up manually or automatically with cups-browsed. A potential queue is an on demand queue. The existing queues may also be enumerated with lpstat -a. Additional entries from lpstat -e are potential queues.

It can happen that a user observes that the print dialog contains two entries with slightly different names for the same physical printer. The two entries are often referred to as duplicate entries or duplicate printers. The user expects to see only one list entry and confusion may result from being unsure which entry should be selected from the dialog list.

CUPS and Driverless Printing: Miscellaneous

http://<IP_address or hostname of the printer>

For a USB connected printer using ipp-usb the URL is

http://localhost:60000

The hostname can be obtained from the output of avahi-browse (see below). Make sure that IPP support and Bonjour broadcasting on the printer are enabled. The configuration options will probably be accessed under a Networking link and it could be that activating AirPrint is sufficient to activate both services.

avahi-browse -rt _ipp._tcp

Bonjour-advertised IPP printers are now identified. Look for entries beginning URF=... and pdl=... . If URF=... exists and pdl=... contains image/urf you have an AirPrint printer.

For an HP Envy 4502:

URF=CP1,MT1-2-8-9-10-11,OB9,OFU0,PQ3-4-5,RS300-600,SRGB24,W8-16,DEVW8-16,DEVRGB24-48,ADOBERGB24-48,DM3,IS1,V1.3
pdl=application/vnd.hp-PCL,image/jpeg,application/PCLm,image/urf

For a Brother MFC-J650DW:

URF = SRGB24,W8,CP1,IS1,MT1-8-11,OB9,PQ4-5,RS300,OFU0,V1.2,DM3
pdl = application/octet-stream,application/vnd.brother-hbp,image/pwg-raster,image/urf,image/jpeg

The pdl entry for the MFC-J650DW has image/pwg-raster. This printer will accept and print PWG raster files. It could be an IPP Everywhere printer, but that all depends on whether it fulfills all the criteria necessary for the manufacturer to self-certify it with the Printer Working Group (PWG). However, the presence of image/urf is a strong enough indication that the printer's IPP implementation is sufficient for driverless printing to be used with CUPS.

Summary

interface = all

Acknowledgements

Didier 'OdyX' Raboud <odyx@debian.org> for guiding and supporting CUPS 2.2.2, cups-filters and cups-browsed through the experimental archive and into unstable; also for packaging ipp-usb and sane-airscan; Till Kamppeter <till.kamppeter@gmail.com> for his integration of cups-filters and cups-browsed with CUPS 2.2.2; also for producing a patch to allow IPP-over-USB to work on localhost with Avahi and encouraging Trent Lloyd <trent.lloyd@canonical.com> to apply it. Michael R. Sweet <msweet@apple.com> for developing the rastertopwg filter to support Apple raster. Alexander Pevzner <pzz@apevzner.com> for the creation of ipp-usb and sane-airscan.

See Also


CategoryPermalink | CategoryPrinter