client.conf(5) — Linux manual page


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

NAME         top

       client.conf - client configuration file for cups (deprecated on

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 "Yes".

       AllowExpiredCerts Yes

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

       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.

       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.

       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

       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

SEE ALSO         top

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

COPYRIGHT         top

       Copyright © 2007-2019 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 2024-06-14.  (At that time,
       the date of the most recent commit that was found in the
       repository was 2023-10-27.)  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

15 October 2019                   CUPS                    client.conf(5)