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: 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 set‐
       tings in the /Library/Preferences/org.cups.PrintingPrefs.plist file instead.  See the NOTES section below for more  informa‐

       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 de‐
            fault 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 sup‐
            ported 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 sup‐
            ported 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 sup‐
            port 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".

       The client.conf file is deprecated on macOS and will no longer be supported in a future version of CUPS.  Configuration set‐
       tings 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 cer‐
       tificates and is used when validating certificates.

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

       Copyright © 2021-2022 by OpenPrinting.

2021-02-28                                                      CUPS                                                 client.conf(5)