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NAME | DESCRIPTION | X.509 CERTIFICATE STORE | X.509 CERTIFICATE VALIDATION | NOTES | SEE ALSO | COPYRIGHT | COLOPHON |
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client.conf(5) OpenPrinting client.conf(5)
client.conf - client configuration file for cups (deprecated on
macos)
The client.conf file configures the CUPS client and is normally
located in the /etc/cups and/or ~/.cups directories. Each line in
the file can be a configuration directive, a blank line, or a
comment. Comment lines start with the # character.
Note: macOS applications can access many of these settings in the
/Library/Preferences/org.cups.PrintingPrefs.plist file instead.
macOS also does not support the ServerName directive. See the
NOTES section below for more information.
DIRECTIVES
The following directives are understood by the client. Consult the
online help for detailed descriptions:
AllowAnyRoot Yes
AllowAnyRoot No
Specifies whether to allow TLS with certificates that have
not been signed by a trusted Certificate Authority. The
default is "Yes".
AllowExpiredCerts Yes
AllowExpiredCerts No
Specifies whether to allow TLS with expired certificates.
The default is "No".
BrowseDomains all
BrowseDomains none
BrowseDomains DOMAIN[,...,DOMAIN]
Specifies the DNS-SD domains to browse for IPP printers. The
value "all" browses the ".local" domain (mDNS) and all
registered DNS domains on the local system. The value "none"
disables browsing for network printers.
DigestOptions DenyMD5
DigestOptions None
Specifies HTTP Digest authentication options. DenyMD5
disables support for the original MD5 hash algorithm.
Encryption IfRequested
Encryption Never
Encryption Required
Specifies the level of encryption that should be used.
FilterLocation LOCATION[,...,LOCATION]
FilterLocation 'LOCATION'[,...,'LOCATION']
FilterLocation "LOCATION"[,...,"LOCATION"]
Specifies a list of locations to use for destinations.
FilterLocation /REGULAR-EXPRESSION/
Specifies a regular expression for matching locations to use
for destinations.
FilterType any
FilterType TYPE[,...,TYPE]
Specifies the type of destinations to use. The TYPE values
are "mono" for B&W printers, "color" for color printers,
"duplex" for printers with 2-sided printing capabilities,
"simplex" for printers with 1-sided printing capabilities,
"bind" for printers that can bind output, "cover" for
printers that can cover output, "punch" for printers that can
punch output, "sort" for printers that can sort output,
"staple" for printers with a stapler, "small" for printers
that support media up to US Legal/ISO A4, "medium" for
printers that support media up to US Tabloid/ISO A3, and
"large" for printers that support media larger than US
Tabloid/ISO A3.
GSSServiceName name
Specifies the Kerberos service name that is used for
authentication, typically "host", "http", or "ipp". CUPS
adds the remote hostname ("[email protected]") for you.
The default name is "http".
ServerName hostname-or-ip-address[:port]
ServerName /domain/socket
Specifies the address and optionally the port to use when
connecting to the server. Note: This directive is not
supported on macOS 10.7 or later.
ServerName hostname-or-ip-address[:port]/version=1.1
Specifies the address and optionally the port to use when
connecting to a server running CUPS 1.3.12 and earlier.
SSLOptions [AllowDH] [AllowRC4] [AllowSSL3] [DenyCBC] [DenyTLS1.0]
[MaxTLS1.0] [MaxTLS1.1] [MaxTLS1.2] [MaxTLS1.3] [MinTLS1.0]
[MinTLS1.1] [MinTLS1.2] [MinTLS1.3]
SSLOptions None
Sets encryption options (only in /etc/cups/client.conf). By
default, CUPS only supports encryption using TLS v1.0 or
higher using known secure cipher suites. Security is reduced
when Allow options are used. Security is enhanced when Deny
options are used. The AllowDH option enables cipher suites
using plain Diffie-Hellman key negotiation (not supported on
systems using GNU TLS). The AllowRC4 option enables the
128-bit RC4 cipher suites, which are required for some older
clients. The AllowSSL3 option enables SSL v3.0, which is
required for some older clients that do not support TLS v1.0.
The DenyCBC option disables all CBC cipher suites. The
DenyTLS1.0 option disables TLS v1.0 support - this sets the
minimum protocol version to TLS v1.1. The MinTLS options set
the minimum TLS version to support. The MaxTLS options set
the maximum TLS version to support. Not all operating
systems support TLS 1.3 at this time.
TrustOnFirstUse Yes
TrustOnFirstUse No
Specifies whether to trust new TLS certificates by default.
The default is "Yes".
User name
Specifies the default user name to use for requests.
UserAgentTokens None
UserAgentTokens ProductOnly
UserAgentTokens Major
UserAgentTokens Minor
UserAgentTokens Minimal
UserAgentTokens OS
UserAgentTokens Full
Specifies what information is included in the User-Agent
header of HTTP requests. "None" disables the User-Agent
header. "ProductOnly" reports "CUPS". "Major" reports
"CUPS/major IPP/2". "Minor" reports "CUPS/major.minor
IPP/2.1". "Minimal" reports "CUPS/major.minor.patch
IPP/2.1". "OS" reports "CUPS/major.minor.path (osname
osversion) IPP/2.1". "Full" reports "CUPS/major.minor.path
(osname osversion; architecture) IPP/2.1". The default is
"Minimal".
ValidateCerts Yes
ValidateCerts No
Specifies whether to only allow TLS with certificates whose
common name matches the hostname. The default is "No".
CUPS uses the system root CA certificate store and per-user
certificate stores managed by CUPS. The per-user certificate
stores are found in "/etc/cups/ssl" for the root user and
"$XDG_CONFIG_HOME/cups/ssl" (Linux/*BSD),
"$HOME/Library/Application Support/cups/ssl" (macOS),
"%USERPROFILE%/AppData/Local/cups" (Windows), and/or
"$HOME/.cups/ssl" for other user accounts.
Certificates, certificate signing requests, and private keys are
stored as PEM-encoded files with the naming convention "COMMON-
NAME.crt" for certificates, "COMMON-NAME.csr" for certificate
signing requests, and "COMMON-NAME.key" for private keys. The
special common name "_site_" is used for a site-specific root
certificate that can be used for trust evaluations.
CUPS supports validation of the certificate's commonName and
subjectAltName field values, the certificate expiration date, and
the certificate's root certificate(s), if any. Self-signed
certificates are "pinned" (stored) to the host in order to do
validation. Validation for certain non-printing servers may add
additional restrictions to the policy defined in the client.conf
file, for example OAuth authorization requires a CA-signed
certificate.
The AllowAnyRoot directive controls whether unpinned self-signed
certificates are acceptable. The TrustOnFirstUse directive
controls whether self-certificates are automatically pinned in the
per-user certificate store for subsequent host validations. When
AllowAnyRoot is disabled, TrustOnFirstUse is also disabled.
Because of sandboxing, the client.conf file is not generally
accessible to applications on macOS. Configuration settings can
instead be viewed or changed using the defaults(1) command:
defaults write /Library/Preferences/org.cups.PrintingPrefs.plist Encryption Required
defaults write /Library/Preferences/org.cups.PrintingPrefs.plist TrustOnFirstUse -bool NO
defaults read /Library/Preferences/org.cups.PrintingPrefs.plist Encryption
On Linux and other systems using GNU TLS, the
/etc/cups/ssl/site.crl file, if present, provides a list of
revoked X.509 certificates and is used when validating
certificates.
cups(1)
Copyright © 2021-2025 by OpenPrinting.
This page is part of the CUPS (a standards-based, open source
printing system) project. Information about the project can be
found at ⟨https://github.com/openprinting/cups⟩. If you have a
bug report for this manual page, see
⟨https://github.com/OpenPrinting/cups/issues⟩. This page was
obtained from the project's upstream Git repository
⟨https://github.com/openprinting/cups⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-07.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
2025-03-04 CUPS client.conf(5)
Pages that refer to this page: cups(1)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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