client.conf(5)                   Apple Inc.                   client.conf(5)

NAME         top

       client.conf - client configuration file for cups

DESCRIPTION         top

       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: Starting with macOS 10.7, this file is only used by command-
       line and X11 applications plus the IPP backend.  The ServerName
       directive is not supported on macOS at all.  Starting with macOS
       10.12, all applications can access these settings in the
       /Library/Preferences/org.cups.PrintingPrefs.plist file instead.  See
       the NOTES section below for more information.

       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

       AllowExpiredCerts Yes

       AllowExpiredCerts No
            Specifies whether to allow TLS with expired certificates.  The
            default is "No".

       Encryption IfRequested

       Encryption Never

       Encryption Required
            Specifies the level of encryption that should be used.

       GSSServiceName name
            Specifies the Kerberos service name that is used for
            authentication, typically "host", "http", or "ipp".  CUPS adds
            the remote hostname ("") 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

       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.

       ValidateCerts Yes

       ValidateCerts No
            Specifies whether to only allow TLS with certificates whose
            common name matches the hostname.  The default is "No".

NOTES         top

       The client.conf file is deprecated on macOS and will no longer be
       supported in a future version of CUPS.  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.

SEE ALSO         top

       cups(1), default(1), CUPS Online Help (http://localhost:631/help)

COPYRIGHT         top

       Copyright © 2007-2018 by Apple Inc.

COLOPHON         top

       This page is part of the CUPS (a standards-based, open source
       printing system) project.  Information about the project can be found
       at ⟨⟩.  If you have a bug report for this manual
       page, see ⟨⟩.  This page was obtained from the
       project's upstream Git repository ⟨⟩ on
       2018-10-29.  (At that time, the date of the most recent commit that
       was found in the repository was 2018-10-25.)  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

3 November 2017                     CUPS                      client.conf(5)