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NAME

     krb5.conf -- configuration file for Kerberos 5

SYNOPSIS

     #include <krb5.h>

DESCRIPTION

     The krb5.conf file specifies several configuration parameters for the
     Kerberos 5 library, as well as for some programs.

     The file consists of one or more sections, containing a number of
     bindings.  The value of each binding can be either a string or a list of
     other bindings.  The grammar looks like:

           file:
                   /* empty */
                   sections

           sections:
                   section sections
                   section

           section:
                   '[' section_name ']' bindings

           section_name:
                   STRING

           bindings:
                   binding bindings
                   binding

           binding:
                   name '=' STRING
                   name '=' '{' bindings '}'

           name:
                   STRING

     STRINGs consists of one or more non-whitespace characters.

     STRINGs that are specified later in this man-page uses the following
     notation.

           boolean
                values can be either yes/true or no/false.

           time
                values can be a list of year, month, day, hour, min, second.
                Example: 1 month 2 days 30 min.  If no unit is given, seconds
                is assumed.

           etypes
                valid encryption types are: des-cbc-crc, des-cbc-md4, des-cbc-
                md5, des3-cbc-sha1, arcfour-hmac-md5, aes128-cts-hmac-sha1-96,
                and aes256-cts-hmac-sha1-96 .

           address
                an address can be either a IPv4 or a IPv6 address.

     Currently recognised sections and bindings are:

           [appdefaults]
                Specifies the default values to be used for Kerberos
                applications.  You can specify defaults per application,
                realm, or a combination of these.  The preference order is:
                1.   application realm option
                2.   application option
                3.   realm option
                4.   option

                The supported options are:

                      forwardable = boolean
                           When obtaining initial credentials, make the
                           credentials forwardable.

                      proxiable = boolean
                           When obtaining initial credentials, make the
                           credentials proxiable.

                      no-addresses = boolean
                           When obtaining initial credentials, request them
                           for an empty set of addresses, making the tickets
                           valid from any address.

                      ticket_lifetime = time
                           Default ticket lifetime.

                      renew_lifetime = time
                           Default renewable ticket lifetime.

                      encrypt = boolean
                           Use encryption, when available.

                      forward = boolean
                           Forward credentials to remote host (for rsh(1),
                           telnet(1), etc).

           [libdefaults]

                      default_realm = REALM
                           Default realm to use, this is also known as your
                           ``local realm''.  The default is the result of
                           krb5_get_host_realm(local hostname).

                      allow_weak_crypto = boolean
                           is weaks crypto algorithms allowed to be used,
                           among others, DES is considered weak.

                      clockskew = time
                           Maximum time differential (in seconds) allowed when
                           comparing times.  Default is 300 seconds (five
                           minutes).

                      kdc_timeout = time
                           Maximum time to wait for a reply from the kdc,
                           default is 3 seconds.

                      v4_name_convert

                      v4_instance_resolve
                           These are described in the
                           krb5_425_conv_principal(3) manual page.

                      capath = {

                                 destination-realm = next-hop-realm

                                 ...

                                 }
                           This is deprecated, see the capaths section below.

                      default_cc_type = cctype
                           sets the default credentials type.

                      default_cc_name = ccname
                           the default credentials cache name.  If you want to
                           change the type only use default_cc_type.  The
                           string can contain variables that are expanded on
                           runtime.  Only support variable now is %{uid} that
                           expands to the current user id.

                      default_etypes = etypes ...
                           A list of default encryption types to use.
                           (Default: all enctypes if allow_weak_crypto = TRUE,
                           else all enctypes except single DES enctypes.)

                      default_as_etypes = etypes ...
                           A list of default encryption types to use in AS
                           requests.  (Default: the value of default_etypes.)

                      default_tgs_etypes = etypes ...
                           A list of default encryption types to use in TGS
                           requests.  (Default: the value of default_etypes.)

                      default_etypes_des = etypes ...
                           A list of default encryption types to use when
                           requesting a DES credential.

                      default_keytab_name = keytab
                           The keytab to use if no other is specified, default
                           is ``FILE:/etc/krb5.keytab''.

                      dns_lookup_kdc = boolean
                           Use DNS SRV records to lookup KDC services
                           location.

                      dns_lookup_realm = boolean
                           Use DNS TXT records to lookup domain to realm
                           mappings.

                      kdc_timesync = boolean
                           Try to keep track of the time differential between
                           the local machine and the KDC, and then compensate
                           for that when issuing requests.

                      max_retries = number
                           The max number of times to try to contact each KDC.

                      large_msg_size = number
                           The threshold where protocols with tiny maximum
                           message sizes are not considered usable to send
                           messages to the KDC.

                      ticket_lifetime = time
                           Default ticket lifetime.

                      renew_lifetime = time
                           Default renewable ticket lifetime.

                      forwardable = boolean
                           When obtaining initial credentials, make the
                           credentials forwardable.  This option is also valid
                           in the [realms] section.

                      proxiable = boolean
                           When obtaining initial credentials, make the
                           credentials proxiable.  This option is also valid
                           in the [realms] section.

                      verify_ap_req_nofail = boolean
                           If enabled, failure to verify credentials against a
                           local key is a fatal error.  The application has to
                           be able to read the corresponding service key for
                           this to work.  Some applications, like su(1),
                           enable this option unconditionally.

                      warn_pwexpire = time
                           How soon to warn for expiring password.  Default is
                           seven days.

                      http_proxy = proxy-spec
                           A HTTP-proxy to use when talking to the KDC via
                           HTTP.

                      dns_proxy = proxy-spec
                           Enable using DNS via HTTP.

                      extra_addresses = address ...
                           A list of addresses to get tickets for along with
                           all local addresses.

                      time_format = string
                           How to print time strings in logs, this string is
                           passed to strftime(3).

                      date_format = string
                           How to print date strings in logs, this string is
                           passed to strftime(3).

                      log_utc = boolean
                           Write log-entries using UTC instead of your local
                           time zone.

                      scan_interfaces = boolean
                           Scan all network interfaces for addresses, as
                           opposed to simply using the address associated with
                           the system's host name.

                      fcache_version = int
                           Use file credential cache format version specified.

                      krb4_get_tickets = boolean
                           Also get Kerberos 4 tickets in kinit, login, and
                           other programs.  This option is also valid in the
                           [realms] section.

                      fcc-mit-ticketflags = boolean
                           Use MIT compatible format for file credential
                           cache.  It's the field ticketflags that is stored
                           in reverse bit order for older than Heimdal 0.7.
                           Setting this flag to TRUE make it store the MIT
                           way, this is default for Heimdal 0.7.

                      check-rd-req-server
                           If set to "ignore", the framework will ignore any
                           the server input to krb5_rd_req(3,) this is very
                           useful when the GSS-API server input the wrong
                           server name into the gss_accept_sec_context call.

                      k5login_directory = directory
                           Alternative location for user .k5login files.
                           Tokens in the form of %{luser} are expanded to the
                           name of the user whose .k5login file is needed.
                           This option is provided for compatibility with MIT
                           krb5 configuration files.

                      k5login_authoritative = boolean
                           If true then if a principal is not found in k5login
                           files then krb5_userok(3) will not fallback on
                           principal to username mapping. This option is
                           provided for compatibility with MIT krb5
                           configuration files.

                      kuserok = rule ...
                           Specifies krb5_userok(3) behavior.  If multiple
                           values are given, then krb5_userok(3) will evaluate
                           them in order until one succeeds or all fail.
                           Rules are implemented by plugins, with three built-
                           in plugins described below. Default: USER-K5LOGIN
                           SIMPLE DENY.

                      kuserok = DENY
                           If set and evaluated then krb5_userok(3) will deny
                           access to the given username no matter what the
                           principal name might be.

                      kuserok = SIMPLE
                           If set and evaluated then krb5_userok(3) will use
                           principal to username mapping (see auth_to_local
                           below).  If the principal maps to the requested
                           username then access is allowed.

                      kuserok = SYSTEM-K5LOGIN[:directory]
                           If set and evaluated then krb5_userok(3) will use
                           k5login files named after the luser argument to
                           krb5_userok(3) in the given directory or in
                           /etc/k5login.d/.  If a directory is given then
                           tokens will be expanded; the %{luser} token will be
                           replaced with the luser argument to krb5_userok(3).
                           K5login files are text files, with each line
                           containing just a principal name; principals
                           apearing in a user's k5login file are permitted
                           access to the user's account. Note: this rule
                           performs no ownership nor permissions checks on
                           k5login files; proper ownership and
                           permissions/ACLs are expected due to the system
                           k5login location being a system location.

                      kuserok = USER-K5LOGIN
                           If set and evaluated then krb5_userok(3) will use
                           ~luser/.k5login and ~luser/.k5login.d/*.  User
                           k5login files and directories must be owned by the
                           user and must not have world nor group write
                           permissions.

                      aname2lname-text-db = filename
                           The named file must be a sorted (in increasing
                           order) text file where every line consists of an
                           unparsed principal name optionally followed by
                           whitespace and a username.  The aname2lname
                           function will do a binary search on this file, if
                           configured, looking for lines that match the given
                           principal name, and if found the given username
                           will be used, or, if the username is missing, an
                           error will be returned.  If the file doesn't exist,
                           or if no matching line is found then other plugins
                           will be allowed to run.

                      name_canon_rules = rules
                           One or more name canonicalization rules.  Each rule
                           consists of one or more tokens separated by colon
                           (':').  The first token must be a rule type, one
                           of: as-is, qualify, use-resolver-searchlist, or
                           nss.  The remaining tokens must be options tokens:
                           secure, ccache_only, use_referrals, no_referrals,
                           mindots= number , domain= domain , and realm=
                           realm. These rules are applied to host-based
                           service principal names in order until one rule
                           succeeds or all fail.  The as-is rules match on
                           number of dots in the hostname or domain suffix of
                           the hostname and attempt the hostname as-is on
                           match.  The qualify rules qualify the hostname with
                           the given domain (and realm, if given) if necessary
                           and attempt the resulting hostname.  The resolver
                           searchlist rule expands to qualify rules using the
                           corresponding domainnames from the DNS resolver's
                           searchlist.  The "nss" rule performs a hostname
                           lookup.  The secure option indicates that an
                           insecure service principal unknown error will
                           result in immediate failure.  Name canonicalization
                           is deferred unless only the default rule is given.
                           Default: nss.

           [domain_realm]
                This is a list of mappings from DNS domain to Kerberos realm.
                Each binding in this section looks like:

                      domain = realm

                The domain can be either a full name of a host or a trailing
                component, in the latter case the domain-string should start
                with a period.  The trailing component only matches hosts that
                are in the same domain, ie ``.example.com'' matches
                ``foo.example.com'', but not ``foo.test.example.com''.

                The realm may be the token `dns_locate', in which case the
                actual realm will be determined using DNS (independently of
                the setting of the `dns_lookup_realm' option).

           [realms]

                      REALM = {

                                 kdc = [service/]host[:port]
                                      Specifies a list of kdcs for this realm.
                                      If the optional port is absent, the
                                      default value for the ``kerberos/udp''
                                      ``kerberos/tcp'', and ``http/tcp'' port
                                      (depending on service) will be used.
                                      The kdcs will be used in the order that
                                      they are specified.

                                      The optional service specifies over what
                                      medium the kdc should be contacted.
                                      Possible services are ``udp'', ``tcp'',
                                      and ``http''.  Http can also be written
                                      as ``http://''.  Default service is
                                      ``udp'' and ``tcp''.

                                 admin_server = host[:port]
                                      Specifies the admin server for this
                                      realm, where all the modifications to
                                      the database are performed.

                                 kpasswd_server = host[:port]
                                      Points to the server where all the
                                      password changes are performed.  If
                                      there is no such entry, the kpasswd port
                                      on the admin_server host will be tried.

                                 krb524_server = host[:port]
                                      Points to the server that does 524
                                      conversions.  If it is not mentioned,
                                      the krb524 port on the kdcs will be
                                      tried.

                                 v4_instance_convert

                                 v4_name_convert

                                 default_domain
                                      See krb5_425_conv_principal(3).

                                 tgs_require_subkey
                                      a boolan variable that defaults to
                                      false.  Old DCE secd (pre 1.1) might
                                      need this to be true.

                                 auth_to_local_names = {

                                            principal_name = username
                                                 The given principal_name will
                                                 be mapped to the given
                                                 username if the REALM is a
                                                 default realm.

                                 }

                                 auth_to_local = HEIMDAL_DEFAULT
                                      Use the Heimdal default principal to
                                      username mapping.  Applies to principals
                                      from the REALM if and only if REALM is a
                                      default realm.

                                 auth_to_local = DEFAULT
                                      Use the MIT default principal to
                                      username mapping.  Applies to principals
                                      from the REALM if and only if REALM is a
                                      default realm.

                                 auth_to_local = DB:/path/to/db.txt
                                      Use a binary search of the given DB.
                                      The DB must be a flat-text file sortedf
                                      in the "C" locale, with each record
                                      being a line (separated by either LF or
                                      CRLF) consisting of a principal name
                                      followed by whitespace followed by a
                                      username.  Applies to principals from
                                      the REALM if and only if REALM is a
                                      default realm.

                                 auth_to_local = DB:/path/to/db
                                      Use the given DB, if there's a plugin
                                      for it.  Applies to principals from the
                                      REALM if and only if REALM is a default
                                      realm.

                                 auth_to_local = RULE:...
                                      Use the given rule, if there's a plugin
                                      for it.  Applies to principals from the
                                      REALM if and only if REALM is a default
                                      realm.

                                 auth_to_local = NONE
                                      No additional principal to username
                                      mapping is done. Note that
                                      auth_to_local_names and any preceding
                                      auth_to_local rules have precedence.

                      }

           [capaths]

                      client-realm = {

                                 server-realm = hop-realm ...
                                      This serves two purposes. First the
                                      first listed hop-realm tells a client
                                      which realm it should contact in order
                                      to ultimately obtain credentials for a
                                      service in the server-realm.  Secondly,
                                      it tells the KDC (and other servers)
                                      which realms are allowed in a multi-hop
                                      traversal from client-realm to
                                      server-realm.  Except for the client
                                      case, the order of the realms are not
                                      important.

                      }

           [logging]

                      entity = destination
                           Specifies that entity should use the specified
                           destination for logging.  See the krb5_openlog(3)
                           manual page for a list of defined destinations.

           [kdc]

                      database = {

                                 dbname = DATABASENAME
                                      Use this database for this realm.  See
                                      the info documetation how to configure
                                      different database backends.

                                 realm = REALM
                                      Specifies the realm that will be stored
                                      in this database.  It realm isn't set,
                                      it will used as the default database,
                                      there can only be one entry that doesn't
                                      have a realm stanza.

                                 mkey_file = FILENAME
                                      Use this keytab file for the master key
                                      of this database.  If not specified
                                      DATABASENAME.mkey will be used.

                                 acl_file = PA FILENAME
                                      Use this file for the ACL list of this
                                      database.

                                 log_file = FILENAME
                                      Use this file as the log of changes
                                      performed to the database.  This file is
                                      used by ipropd-master for propagating
                                      changes to slaves.

                      }

                      max-request = SIZE
                           Maximum size of a kdc request.

                      require-preauth = BOOL
                           If set pre-authentication is required.  Since krb4
                           requests are not pre-authenticated they will be
                           rejected.

                      ports = list of ports
                           List of ports the kdc should listen to.

                      addresses = list of interfaces
                           List of addresses the kdc should bind to.

                      enable-kerberos4 = BOOL
                           Turn on Kerberos 4 support.

                      v4-realm = REALM
                           To what realm v4 requests should be mapped.

                      enable-524 = BOOL
                           Should the Kerberos 524 converting facility be
                           turned on.  Default is the same as
                           enable-kerberos4.

                      enable-http = BOOL
                           Should the kdc answer kdc-requests over http.

                      tgt-use-strongest-session-key = BOOL
                           If this is TRUE then the KDC will prefer the
                           strongest key from the client's AS-REQ or TGS-REQ
                           enctype list for the ticket session key that is
                           supported by the KDC and the target principal when
                           the target principal is a krbtgt principal.  Else
                           it will prefer the first key from the client's AS-
                           REQ enctype list that is also supported by the KDC
                           and the target principal. Defaults to TRUE.

                      svc-use-strongest-session-key = BOOL
                           Like tgt-use-strongest-session-key, but applies to
                           the session key enctype of tickets for services
                           other than krbtgt principals. Defaults to TRUE.

                      preauth-use-strongest-session-key = BOOL
                           If TRUE then select the strongest possible enctype
                           from the client's AS-REQ for PA-ETYPE-INFO2 (i.e.,
                           for password-based pre-authentication).  Else pick
                           the first supported enctype from the client's AS-
                           REQ. Defaults to TRUE.

                      use-strongest-server-key = BOOL
                           If TRUE then the KDC picks, for the ticket
                           encrypted part's key, the first supported enctype
                           from the target service principal's hdb entry's
                           current keyset. Else the KDC picks the first
                           supported enctype from the target service
                           principal's hdb entry's current keyset. Defaults to
                           TRUE.

                      check-ticket-addresses = BOOL
                           Verify the addresses in the tickets used in tgs
                           requests.

                      allow-null-ticket-addresses = BOOL
                           Allow address-less tickets.

                      allow-anonymous = BOOL
                           If the kdc is allowed to hand out anonymous
                           tickets.

                      encode_as_rep_as_tgs_rep = BOOL
                           Encode as-rep as tgs-rep tobe compatible with
                           mistakes older DCE secd did.

                      kdc_warn_pwexpire = TIME
                           The time before expiration that the user should be
                           warned that her password is about to expire.

                      logging = Logging
                           What type of logging the kdc should use, see also
                           [logging]/kdc.

                      use_2b = {

                                 principal = BOOL
                                      boolean value if the 524 daemon should
                                      return AFS 2b tokens for principal.

                                 ...

                      }

                      hdb-ldap-structural-object structural object
                           If the LDAP backend is used for storing principals,
                           this is the structural object that will be used
                           when creating and when reading objects.  The
                           default value is account .

                      hdb-ldap-create-base creation dn
                           is the dn that will be appended to the principal
                           when creating entries.  Default value is the search
                           dn.

                      enable-digest = BOOL
                           Should the kdc answer digest requests. The default
                           is FALSE.

                      digests_allowed = list of digests
                           Specifies the digests the kdc will reply to. The
                           default is ntlm-v2.

           [kadmin]

                      require-preauth = BOOL
                           If pre-authentication is required to talk to the
                           kadmin server.

                      password_lifetime = time
                           If a principal already have its password set for
                           expiration, this is the time it will be valid for
                           after a change.

                      default_keys = keytypes...
                           For each entry in default_keys try to parse it as a
                           sequence of etype:salttype:salt syntax of this if
                           something like:

                           [(des|des3|etype):](pw-salt|afs3-salt)[:string]

                           If etype is omitted it means everything, and if
                           string is omitted it means the default salt string
                           (for that principal and encryption type).
                           Additional special values of keytypes are:

                                 v5   The Kerberos 5 salt pw-salt

                                 v4   The Kerberos 4 salt des:pw-salt:

                      use_v4_salt = BOOL
                           When true, this is the same as

                           default_keys = des3:pw-salt v4

                           and is only left for backwards compatibility.

           [password_quality]
                Check the Password quality assurance in the info documentation
                for more information.

                      check_library = library-name
                           Library name that contains the password
                           check_function

                      check_function = function-name
                           Function name for checking passwords in
                           check_library

                      policy_libraries = library1 ... libraryN
                           List of libraries that can do password policy
                           checks

                      policies = policy1 ... policyN
                           List of policy names to apply to the password.
                           Builtin policies are among other minimum-length,
                           character-class, external-check.

ENVIRONMENT

     KRB5_CONFIG points to the configuration file to read.

FILES

     /etc/krb5.conf  configuration file for Kerberos 5.

EXAMPLES

           [libdefaults]
                   default_realm = FOO.SE
                   name_canon_rules = as-is:realm=FOO.SE
                   name_canon_rules = qualify:domain=foo.se:realm=FOO.SE
                   name_canon_rules = qualify:domain=bar.se:realm=FOO.SE
                   name_canon_rules = nss
           [domain_realm]
                   .foo.se = FOO.SE
                   .bar.se = FOO.SE
           [realms]
                   FOO.SE = {
                           kdc = kerberos.foo.se
                           v4_name_convert = {
                                   rcmd = host
                           }
                           v4_instance_convert = {
                                   xyz = xyz.bar.se
                           }
                           default_domain = foo.se
                   }
           [logging]
                   kdc = FILE:/var/heimdal/kdc.log
                   kdc = SYSLOG:INFO
                   default = SYSLOG:INFO:USER

DIAGNOSTICS

     Since krb5.conf is read and parsed by the krb5 library, there is not a
     lot of opportunities for programs to report parsing errors in any useful
     format.  To help overcome this problem, there is a program
     verify_krb5_conf that reads krb5.conf and tries to emit useful
     diagnostics from parsing errors.  Note that this program does not have
     any way of knowing what options are actually used and thus cannot warn
     about unknown or misspelled ones.

SEE ALSO

     kinit(1), krb5_425_conv_principal(3), krb5_openlog(3), strftime(3),
     verify_krb5_conf(8)