cups-browsed.conf - server configuration file for cups-browsed
The cups-browsed.conf file configures the cups-browsed daemon. It is normally located in the /etc/cups directory. Each line in the file can be a configuration directive, a blank line, or a comment. Comment lines start with the # character.
The "CacheDir" directive determines where cups-browsed should save information about the print queues it had generated when shutting down, like whether one of these queues was the default printer, or default option settings of the queues.
With "LogDir" can be defined where cups-browsed creates its debug log file (if "DebugLogging file" is set).
The "DebugLogging" directive determines how should debug logging be done. Into the file /var/log/cups/cups-browsed_log ("file"), to stderr ("stderr"), or not at all ("none").
Note that if cups-browsed is running as a system service (for example via systemd) logging to stderr makes the log output going to the journal or syslog. Only if you run cups-browsed from the command line (for development or debugging) it will actually appear on stderr.
DebugLogging file stderr
Only browse remote printers (via DNS-SD or CUPS browsing) from selected servers using the "BrowseAllow", "BrowseDeny", and "BrowseOrder" directives
This serves for restricting the choice of printers in print dialogs to trusted servers or to reduce the number of listed printers in the print dialogs to a more user-friendly amount in large networks with very many shared printers.
This only filters the selection of remote printers for which cups-browsed creates local queues. If the print dialog uses other mechanisms to list remote printers as for example direct DNS-SD access, cups-browsed has no influence. cups-browsed also does not prevent the user from manually accessing non-listed printers.
"BrowseAllow": Accept printers from these hosts or networks. If there are only "BrowseAllow" lines and no "BrowseOrder" and/or "BrowseDeny" lines, only servers matching at last one "BrowseAllow" line are accepted.
"BrowseDeny": Deny printers from these hosts or networks. If there are only "BrowseDeny" lines and no "BrowseOrder" and/or "BrowseAllow" lines, all servers NOT matching any of the "BrowseDeny" lines are accepted.
"BrowseOrder": Determine the order in which "BrowseAllow" and "BrowseDeny" lines are applied. With "BrowseOrder Deny,Allow" in the beginning all servers are accepted, then the "BrowseDeny" lines are applied to exclude unwished servers or networks and after that the "BrowseAllow" lines to re-include servers or networks. With "BrowseOrder Allow,Deny" we start with denying all servers, then applying the "BrowseAllow" lines and afterwards the "BrowseDeny" lines.
Default for "BrowseOrder" is "Deny.Allow" if there are both "BrowseAllow" and "BrowseDeny" lines.
If there are no "Browse..." lines at all, all servers are accepted.
Filtering of remote printers by other properties than IP addresses of their servers
Often the desired selection of printers cannot be reached by only taking into account the IP addresses of the servers. For these cases there is the BrowseFilter directive to filter by most of the known properties of the printer.
By default there is no BrowseFilter line meaning that no filtering is applied.
To do filtering one can supply one or more BrowseFilter directives like this:
BrowseFilter [NOT] [EXACT] <FIELD> [<VALUE>]
The BrowseFilter directive always starts with the word "BrowseFilter" and it must at least contain the name of the data field (<FIELD>) of the printer’s properties to which it should apply.
Available field names are:
name: Name of
the local print queue to be created
host: Host name of the remote print server
port: Port through which the printer is accessed on the server
service: DNS/SD service name of the remote printer
domain: Domain of the remote print server
Also all field names in the TXT records of DNS-SD-advertised printers are valid, like "color", "duplex", "pdl", ... If the field name of the filter rule does not exist for the printer, the rule is skipped.
The optional <VALUE> field is either the exact value (when the option EXACT is supplied) or a regular expression (Run "man 7 regex" in a terminal window) to be matched with the data field.
If no <VALUE> filed is supplied, rules with field names of the TXT record are considered for boolean matching (true/false) of boolean field (like duplex, which can have the values "T" for true and "F" for false).
If the option NOT is supplied, the filter rule is fulfilled if the regular expression or the exact value DOES NOT match the content of the data field. In a boolean rule (without <VALUE>) the rule matches false.
Regular expressions are always considered case-insensitive and extended POSIX regular expressions. Field names and options (NOT, EXACT) are all evaluated case-insensitive. If there is an error in a regular expression, the BrowseFilter line gets ignored.
Especially to note is that supplying any simple string consisting of only letters, numbers, spaces, and some basic special characters as a regular expression matches if it is contained somewhere in the data field.
If there is more than one BrowseFilter directive, ALL the directives need to be fulfilled for the remote printer to be accepted. If one is not fulfilled, the printer will get ignored.
Rules for standard data items which are supplied with any remote printer advertised via DNS-SD:
Print queue name must contain "hum_res_", this matches "hum_res_mono" or "hum_res_color" but also "old_hum_res_mono":
BrowseFilter name hum_res_
This matches if the remote host name contains "printserver", like "printserver.local", "printserver2.example.com", "newprintserver":
BrowseFilter host printserver
This matches all ports with 631 int its number, for example 631, 8631, 10631,...:
BrowseFilter port 631
This rule matches if the DNS-SD service name contains "@ printserver":
Browsefilter service @ printserver
Matches all domains with "local" in their names, not only "local" but also things like "printlocally.com":
BrowseFilter domain local
Examples for rules applying to items of the TXT record:
This rule selects PostScript printers, as the "PDL" field in the TXT record contains "postscript" then. This includes also remote CUPS queues which accept PostScript, independent of whether the physical printer behind the CUPS queue accepts PostScript or not.
BrowseFilter pdl postscript
Color printers usually contain a "Color" entry set to "T" (for true) in the TXT record. This rule selects them:
This is a similar rule to select only duplex (automatic double-sided printing) printers:
Rules with the NOT option:
This rule EXCLUDES printers from all hosts containing "financial" in their names, nice to get rid of the 100s of printers of the financial department:
BrowseFilter NOT host financial
Get only monochrome printers ("Color" set to "F", meaning false, in the TXT record):
BrowseFilter NOT color
Rules with more advanced use of regular expressions:
Only queue names which BEGIN WITH "hum_res_" are accepted now, so we still get "hum_res_mono" or "hum_res_color" but not "old_hum_res_mono" any more:
BrowseFilter name ^hum_res_
Server names is accepted if it contains "print_server" OR "graphics_dep_server":
BrowseFilter host print_server|graphics_dep_server
"printserver1", "printserver2", and "printserver3", nothing else:
BrowseFilter host ^printserver[1-3]$
Printers understanding at least one of PostScript, PCL, or PDF:
BrowseFilter pdl postscript|pcl|pdf
Examples for the EXACT option:
Only printers from "printserver.local" are accepted:
BrowseFilter EXACT host printserver.local
Printers from all servers except "prinserver2.local" are accepted:
BrowseFilter NOT EXACT host prinserver2.local
The BrowsePoll directive polls a server for available printers once every 60 seconds. Multiple BrowsePoll directives can be specified to poll multiple servers. The default port to connect to is 631. BrowsePoll works independently of whether CUPS browsing is activated in BrowseRemoteProtocols.
The BrowseLocalProtocols directive specifies the protocols to use when advertising local shared printers on the network. The default is "none". Control of advertising of local shared printers using dnssd is done in /etc/cups/cupsd.conf.
The BrowseRemoteProtocols directive specifies the protocols to use when finding remote shared printers on the network. Multiple protocols can be specified by separating them with spaces. The default is "dnssd cups".
BrowseRemoteProtocols CUPS dnssd
The BrowseProtocols directive specifies the protocols to use when finding remote shared printers on the network and advertising local shared printers. "dnssd" and "ldap" are ignored for BrowseLocalProtocols. Multiple protocols can be specified by separating them with spaces. The default is "none" for BrowseLocalProtocols and "dnssd cups" for BrowseRemoteProtocols.
BrowseProtocols CUPS dnssd
The configuration for the LDAP browsing mode define where the LDAP search should be performed. If built with an LDAP library that supports TLS, the path to the server’s certificate, or to a certificates store, can be specified. The optional filter allows the LDAP search to be more specific, and is used in addition to the hardcoded filter (objectclass=cupsPrinter).
BrowseLDAPFilter (printerLocation=/Office 1/*)
The DomainSocket directive specifies the domain socket through which the locally running CUPS daemon is accessed. If not specified the standard domain socket of CUPS is used. Use this if you have specified an alternative domain socket for CUPS via a Listen directive in /etc/cups/cupsd.conf. If cups-browsed is not able to access the local CUPS daemon via a domain socket it accesses it via localhost. "None" or "Off" lets cups-browsed not use CUPS’ domain socket.
Set HTTP timeout (in seconds) for requests sent to local/remote resources Note that too short timeouts can make services getting missed when they are present and operations be unneccessarily repeated and too long timeouts can make operations take too long when the server does not respond.
Set how many retries (N) should cups-browsed do for creating print queues for remote printers which receive timeouts during print queue creation. The printers which are not successfuly set up even after N retries, are skipped until the next restart of the service. Note that too many retries can cause high CPU load.
The interval between browsing/broadcasting cycles, local and/or remote, can be adjusted with the BrowseInterval directive.
The BrowseTimeout directive determines the amount of time that browsing-related operations are allowed to take in seconds. Notably, adding or removing one printer queue is considered as one operation. The timeout applies to each one of those operations. Especially queues discovered by CUPS broadcasts will be removed after this timeout if no further broadcast from the server happens.
Set OnlyUnsupportedByCUPS to "Yes" will make cups-browsed not create local queues for remote printers for which CUPS creates queues by itself. These printers are printers advertised via DNS-SD and doing CUPS-supported (currently PWG Raster and Apple Raster) driverless printing, including remote CUPS queues. Queues for other printers (like for legacy PostScript/PCL printers) are always created (depending on the other configuration settings of cups-browsed).
With OnlyUnsupportedByCUPS set to "No", cups-browsed creates queues for all printers which it supports, including printers for which CUPS would create queues by itself. Temporary queues created by CUPS will get overwritten. This way it is assured that any extra functionality of cups-browsed will apply to these queues. As queues created by cups-browsed are permanent CUPS queues this setting is also recommended if applications/print dialogs which do not support temporary CUPS queues are installed. This setting is the default.
With UseCUPSGeneratedPPDs set to "Yes" cups-browsed creates queues for IPP printers with PPDs generated by the PPD generator of CUPS and not with the one of cups-browsed. So any new development in CUPS’ PPD generator gets available. As CUPS’ PPD generator is not directly accessible, we need to make CUPS generate a temporary print queue with the desired PPD. Therefore we can only use these PPDs when our queue replaces a temporary CUPS queue, meaning that the queue is for a printer on which CUPS supports driverless printing (IPP 2.x, PDLs: PDF, PWG Raster, and/or Apple Raster) and that its name is the same as CUPS uses for the temporary queue ("LocalQueueNamingIPPPrinter DNS-SD" must be set). The directive applies only to IPP printers, not to remote CUPS queues, to not break clustering. Setting this directive to "No" lets cups-browsed generate the PPD file. Default setting is "Yes".
With the directives LocalQueueNamingRemoteCUPS and LocalQueueNamingIPPPrinter you can determine how the names for local queues generated by cups-browsed are generated, separately for remote CUPS printers and IPP printers.
"DNS-SD" (the default in both cases) bases the naming on the service name of the printer’s advertised DNS-SD record. This is exactly the same naming scheme as CUPS uses for its temporary queues, so the local queue from cups-browsed prevents CUPS from listing and creating an additional queue. As DNS-SD service names have to be unique, queue names of printers from different servers will also be unique and so there is no automatic clustering for load-balanced printing.
"MakeModel" bases the queue name on the printer’s manufacturer and model names. This scheme cups-browsed used formerly for IPP printers.
"RemoteName" is only available for remote CUPS queues and uses the name of the queue on the remote CUPS server as the local queue’s name. This makes printers on different CUPS servers with equal queue names automatically forming a load-balancing cluster as CUPS did formerly (CUPS 1.5.x and older) with CUPS-broadcasted remote printers. This scheme cups-browsed used formerly for remote CUPS printers.
Set IPBasedDeviceURIs to "Yes" if cups-browsed should create its local queues with device URIs with the IP addresses instead of the host names of the remote servers. This mode is there for any problems with host name resolution in the network, especially also if avahi-daemon is only run for printer discovery and already stopped while still printing. By default this mode is turned off, meaning that we use URIs with host names.
If you prefer IPv4 or IPv6 IP addresses in the URIs, you can set IPBasedDeviceURIs to "IPv4" to only get IPv4 IP addresses or IPBasedDeviceURIs to "IPv6" to only get IPv6 IP addresses.
Set CreateRemoteRawPrinterQueues to "Yes" to let cups-browsed also create local queues pointing to remote raw CUPS queues. Normally, only queues pointing to remote queues with PPD/driver are created as we do not use drivers on the client side, but in some cases accessing a remote raw queue can make sense, for example if the queue forwards the jobs by a special backend like Tea4CUPS.
cups-browsed by default creates local print queues for each shared CUPS print queue which it discovers on remote machines in the local network(s). Set CreateRemoteCUPSPrinterQueues to "No" if you do not want cups-browsed to do this. For example you can set cups-browsed to only create queues for IPP network printers setting CreateIPPPrinterQueues not to "No" and CreateRemoteCUPSPrinterQueues to "No".
Set CreateIPPPrinterQueues to "All" to let cups-browsed discover IPP network printers (native printers, not CUPS queues) with known page description languages (PWG Raster, PDF, PostScript, PCL XL, PCL 5c/e) in the local network and auto-create print queues for them.
Set CreateIPPPrinterQueues to "Everywhere" to let cups-browsed discover IPP Everywhere printers in the local network (native printers, not CUPS queues) and auto-create print queues for them.
Set CreateIPPPrinterQueues to "AppleRaster" to let cups-browsed discover Apple Raster printers in the local network (native printers, not CUPS queues) and auto-create print queues for them.
Set CreateIPPPrinterQueues to "Driverless" to let cups-browsed discover printers designed for driverless use (currently IPP Everywhere and Apple Raster) in the local network (native printers, not CUPS queues) and auto-create print queues for them.
Set CreateIPPPrinterQueues to "LocalOnly" to auto-create print queues only for local printers made available as IPP printers. These are for example IPP-over-USB printers, made available via ippusbxd(8). This is the default.
Set CreateIPPPrinterQueues to "No" to not auto-create print queues for IPP network printers.
If queues with PPD file are created (see IPPPrinterQueueType directive below) the PPDs are auto-generated by cups-browsed based on properties of the printer polled via IPP. In case of missing information, info from the Bonjour record is used asd as last mean default values.
If queues without PPD (see IPPPrinterQueueType directive below) are created clients have to IPP-poll the capabilities of the printer and send option settings as standard IPP attributes. Then we do not poll the capabilities by ourselves to not wake up the printer from power-saving mode when creating the queues. Jobs have to be sent in one of PDF, PWG Raster, or JPEG format. Other formats are not accepted.
This functionality is primarily for mobile devices running CUPS to not need a printer setup tool nor a collection of printer drivers and PPDs.
CreateIPPPrinterQueues Everywhere AppleRaster
If cups-browsed is automatically creating print queues for native IPP network printers ("CreateIPPPrinterQueues Yes"), the type of queue to be created can be selected by the "IPPPrinterQueueType" directive. The "PPD" (default) setting makes queues with PPD file being created. With "Interface" or "NoPPD" the queue is created with a System V interface script (Not supported with CUPS 2.2.x or later). "Auto" is for backward compatibility and also lets queues with PPD get created.
The NewIPPPrinterQueuesShared directive determines whether a print queue for a newly discovered IPP network printer (not remote CUPS queue) will be shared to the local network or not. This is only valid for newly discovered printers. For printers discovered in an earlier cups-browsed session, cups-browsed will remember whether the printer was shared, so changes by the user get conserved. Default is not to share newly discovered IPP printers.
If there is more than one remote CUPS printer whose local queue would get the same name and AutoClustering is set to "Yes" (the default) only one local queue is created which makes up a load-balancing cluster of the remote printers which would get this queue name (implicit class). This means that when several jobs are sent to this queue they get distributed between the printers, using the method chosen by the LoadBalancing directive.
Note that the forming of clusters depends on the naming scheme for local queues created by cups-browsed. If you have set LocalQueueNamingRemoteCUPS to "DNSSD" you will not get automatic clustering as the DNS-SD service names are always unique. With LocalQueueNamingRemoteCUPS set to "RemoteName" local queues are named as the CUPS queues on the remote servers are named and so equally named queues on different servers get clustered (this is how CUPS did it in version 1.5.x or older). LocalQueueNamingRemoteCUPS set to "MakeModel" makes remote printers of the same model get clustered. Note that then a cluster can contain more than one queue of the same server.
With AutoClustering set to "No", for each remote CUPS printer an individual local queue is created, and to avoid name clashes when using the LocalQueueNamingRemoteCUPS settings "RemoteName" or "MakeModel" "@<server name>" is added to the local queue name.
Only remote CUPS printers get clustered, not IPP network printers or IPP-over-USB printers.
Load-balancing printer cluster formation can also be manually controlled by defining explicitly which remote CUPS printers should get clustered together.
This is done by the "Cluster" directive:
<QUEUENAME>: <EXPRESSION1> <EXPRESSION2>
If no expressions are given, <QUEUENAME> is used as the first and only expression for this cluster.
Discovered printers are matched against all the expressions of all defined clusters. The first expression which matches the discovered printer determines to which cluster it belongs. Note that this way a printer can only belong to one cluster. Once matched, further cluster definitions will not checked any more.
With the first printer matching a cluster’s expression a local queue with the name <QUEUENAME> is created. If more printers are discovered and match this cluster, they join the cluster. Printing to this queue prints to all these printers in a load-balancing manner, according to to the setting of the LoadBalancing directive.
Each expression must be a string of characters without spaces. If spaces are needed, replace them by underscores (’_’).
An expression can be matched in three ways:
1. By the name
of the CUPS queue on the remote server
2. By make and model name of the remote printer
3. By the DNS-SD service name of the remote printer
Note that the matching is done case-insensitively and any group of non-alphanumerical characters is replaced by a single underscore.
So if an expression is "HP_DeskJet_2540" and the remote server reports "hp Deskjet-2540" the printer gets matched to this cluster.
If "AutoClustering" is not set to "No" both your manual cluster definitions will be followed and automatic clustering of equally-named remote queues will be performed. If a printer matches in both categories the match to the manually defined cluster has priority. Automatic clustering of equally-named remote printers is not performed if there is a manually defined cluster with this name (at least as the printers do not match this cluster).
To cluster all remote CUPS queues named "laserprinter" in your local network but not cluster any other equally-named remote CUPS printers use (Local queue will get named "laserprinter"):
To cluster all remote CUPS queues of HP LaserJet 4050 printers in a local queue named "LJ4050":
Cluster LJ4050: HP_LaserJet_4050
As DNS-SD service names are unique in a network you can create a cluster from exactly specified printers (spaces replaced by underscors):
Cluster hrdep: oldlaser_@_hr-server1 newlaser_@_hr-server2
The LoadBalancing directive switches between two methods of handling load balancing between equally-named remote queues which are represented by one local print queue making up a cluster of them (implicit class).
The two methods are:
Queuing of jobs on the client (LoadBalancing QueueOnClient):
Here we queue up the jobs on the client and regularly check the clustered remote print queues. If we find an idle queue, we pass on a job to it.
This is also the method which CUPS uses for classes. Advantage is a more even distribution of the job workload on the servers (especially if the printing speed of the servers is very different), and if a server fails, there are not several jobs stuck or lost. Disadvantage is that if one takes the client (laptop, mobile phone, ...) out of the local network, printing stops with the jobs waiting in the local queue.
Queuing of jobs on the servers (LoadBalancing QueueOnServers):
Here we check the number of jobs on each of the clustered remote printers and send an incoming job immediately to the remote printer with the lowest amount of jobs in its queue. This way no jobs queue up locally, all jobs which are waiting are waiting on one of the remote servers.
Not having jobs waiting locally has the advantage that we can take the local machine from the network and all jobs get printed. Disadvantage is that if a server with a full queue of jobs goes away, the jobs go away, too.
Default is queuing the jobs on the client as this is what CUPS does with classes.
With the DefaultOptions directive one or more option settings can be defined to be applied to every print queue newly created by cups-browsed. Each option is supplied as one supplies options with the "-o" command line argument to the "lpadmin" command (Run "man lpadmin" for more details). More than one option can be supplied separating the options by spaces. By default no option settings are pre-defined.
Note that print queues which cups-browsed already created before remember their previous settings and so these settings do not get applied.
DefaultOptions Option1=Value1 Option2=Value2 Option3 noOption4
The AutoShutdown directive specifies whether cups-browsed should automatically terminate when it has no local raw queues set up pointing to any discovered remote printers or no jobs on such queues depending on AutoShutdownOn setting (auto shutdown mode). Setting it to "On" activates the auto-shutdown mode, setting it to "Off" deactivates it (the default). The special mode "avahi" turns auto shutdown off while avahi-daemon is running and on when avahi-daemon stops. This allows running cups-browsed on-demand when avahi-daemon is run on-demand.
The AutoShutdownOn directive determines what event cups-browsed considers as inactivity in auto shutdown mode. "NoQueues" (the default) means that auto shutdown is initiated when there are no queues for discovered remote printers generated by cups-browsed any more. "NoJobs" means that all queues generated by cups-browsed are without jobs.
The AutoShutdownTimeout directive specifies after how many seconds without local raw queues set up pointing to any discovered remote printers or jobs on these queues cups-browsed should actually shut down in auto shutdown mode. Default is 30 seconds, 0 means immediate shutdown.
The authors of cups-browsed are listed in /usr/share/doc/cups-browsed/AUTHORS.
This manual page was written for the Debian Project, but it may be used by others.