
KRB5.CONF(5)                BSD File Formats Manual               KRB5.CONF(5)

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 bind-
     ings.  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 applica-
                tions.  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 cre-
                           dentials forwardable.

                      proxiable = boolean
                           When obtaining initial credentials, make the cre-
                           dentials 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
                           are weak 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 min-
                           utes).

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

                      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.  The Only supported variable currently is
                           %{uid} which 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 loca-
                           tion.

                      dns_lookup_realm = boolean
                           Use DNS TXT records to lookup domain to realm map-
                           pings.

                      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 cre-
                           dentials forwardable.  This option is also valid in
                           the [realms] section.

                      proxiable = boolean
                           When obtaining initial credentials, make the cre-
                           dentials 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.

                      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 makes 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
                           of 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. 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 pro-
                           vided 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/.  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 permis-
                           sions/ACLs are expected due to the 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 per-
                           missions.

                      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 func-
                           tion will do a binary search on this file, if con-
                           figured, 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.

                      fcache_strict_checking
                           strict checking in FILE credential caches that
                           owner, no symlink and permissions is correct.

                      name_canon_rules = rules
                           One or more service principal name canonicalization
                           rules.  Each rule consists of one or more tokens
                           separated by colon (':').  Currently these rules
                           are used only for hostname canonicalization (usu-
                           ally when getting a service ticket, from a ccache
                           or a TGS, but also when acquiring GSS initiator
                           credentials from a keytab).  These rules can be
                           used to implement DNS resolver-like search lists
                           without having to use DNS.

                           NOTE: Name canonicalization rules are an experimen-
                           tal feature.

                           The first token is a rule type, one of: as-is,
                           qualify, or nss.

                           Any remaining tokens must be options tokens:
                           use_fast (use FAST to protect TGS exchanges; cur-
                           rently not supported), use_dnssec (use DNSSEC to
                           protect hostname lookups; currently not supported),
                           ccache_only , use_referrals, no_referrals,
                           lookup_realm, mindots=N, maxdots=N, order=N,
                           domain= domain, realm= realm, match_domain= domain,
                           and match_realm= realm.

                           When trying to obtain a service ticket for a host-
                           based service principal name, name canonicalization
                           rules are applied to that name in the order given,
                           one by one, until one succeds (a service ticket is
                           obtained), or all fail.  Similarly when acquiring
                           GSS initiator credentials from a keytab, and when
                           comparing a non-canonical GSS name to a canonical
                           one.

                           For each rule the system checks that the hostname
                           has at least mindots periods (if given) in it, at
                           most maxdots periods (if given), that the hostname
                           ends in the given match_domain (if given), and that
                           the realm of the principal matches the match_realm
                           (if given).

                           As-is rules leave the hostname unmodified but may
                           set a realm.  Qualify rules qualify the hostname
                           with the given domain and also may set the realm.
                           The nss rule uses the system resolver to lookup the
                           host's canonical name and is usually not secure.
                           Note that using the nss rule type implies having to
                           have principal aliases in the HDB (though not nec-
                           essarily in keytabs).

                           The empty realm denotes "ask the client's realm's
                           TGS".  The empty realm may be set as well as
                           matched.

                           The order in which rules are applied is as follows:
                           first all the rules with explicit order then all
                           other rules in the order in which they appear.  If
                           any two rules have the same explicit order, their
                           order of appearance in krb5.conf breaks the tie.
                           Explicitly specifying order can be useful where
                           tools read and write the configuration file without
                           preserving parameter order.

                           Malformed rules are ignored.

                      allow_hierarchical_capaths = boolean
                           When validating cross-realm transit paths, absent
                           any explicit capath from the client realm to the
                           server realm, allow a hierarchical transit path via
                           the common ancestor domain of the two realms.
                           Defaults to true.  Note, absent an explicit set-
                           ting, hierarchical capaths are always used by the
                           KDC when generating a referral to a destination
                           with which is no direct trust.

           [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 pass-
                                      word changes are performed.  If there is
                                      no such entry, the kpasswd port on the
                                      admin_server host will be tried.

                                 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 user-
                                      name 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 map-
                                      ping 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 = [DATBASETYPE:]DATABASENAME
                                      Use this database for this realm.  The
                                      DATABASETYPE should be one of 'lmdb',
                                      'db3', 'db1', 'db', 'sqlite', or 'ldap'.
                                      See the info documetation how to config-
                                      ure 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 per-
                                      formed to the database.  This file is
                                      used by ipropd-master for propagating
                                      changes to slaves.  It is also used by
                                      kadmind and kadmin (when used with the
                                      -l option), and by all applications
                                      using libkadm5 with the local backend,
                                      for two-phase commit functionality.
                                      Slaves also use this.  Setting this to
                                      /dev/null disables two-phase commit and
                                      incremental propagation.  Use iprop-log
                                      to show the contents of this log file.

                                 log-max-size = number
                                      When the log reaches this size (in
                                      bytes), the log will be truncated, sav-
                                      ing some entries, and keeping the latest
                                      version number so as to not disrupt
                                      incremental propagation.  If set to a
                                      negative value then automatic log trun-
                                      cation will be disabled.  Defaults to
                                      52428800 (50MB).

                      }

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

                      require-preauth = BOOL
                           If set pre-authentication is required.

                      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-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 FALSE.

                      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 FALSE.

                      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 FALSE.

                      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 sup-
                           ported 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 tick-
                           ets.

                      encode_as_rep_as_tgs_rep = BOOL
                           Encode as-rep as tgs-rep tobe compatible with mis-
                           takes 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.

                      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.

                      kx509_ca = file
                           Specifies the PEM credentials for the kx509 certi-
                           fication authority.

                      require_initial_kca_tickets = boolean
                           Specified whether to require that tickets for the
                           kca_service service principal be INITIAL.  This may
                           be set on a per-realm basis as well as globally.
                           Defaults to true for the global setting.

                      kx509_include_pkinit_san = boolean
                           If true then the kx509 client principal's name and
                           realm will be included in an id-pkinit-san certifi-
                           cate extension.  This can be set on a per-realm
                           basis as well as globally.  Defaults to true for
                           the global setting.

                      kx509_template = file
                           Specifies the PEM file with a template for the cer-
                           tificates to be issued.  The following variables
                           can be interpolated in the subject name using
                           ${variable} syntax:

                                 principal-name
                                      The full name of the kx509 client prin-
                                      cipal.

                                 principal-name-without-realm
                                      The full name of the kx509 client prin-
                                      cipal, excluding the realm name.

                                 principal-name-realm
                                      The name of the client principal's
                                      realm.
                The kx509, kx509_template, kx509_include_pkinit_san, and
                require_initial_kca_tickets parameters may be set on a per-
                realm basis as well.

           [kadmin]

                      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).  Addi-
                           tional special values of keytypes are:

                                 v5   The Kerberos 5 salt pw-salt

                      default_key_rules = {

                                 globing-rule = keytypes...
                                      a globbing rule to matching a principal,
                                      and when true, use the keytypes as spec-
                                      ified the same format as [kad-
                                      min]default_keys .

                      }

                      prune-key-history = BOOL
                           When adding keys to the key history, drop keys that
                           are too old to match unexpired tickets (based on
                           the principal's maximum ticket lifetime).  If the
                           KDC keystore is later compromised traffic protected
                           with the discarded older keys may remain protected.
                           This also keeps the HDB records for principals with
                           key history from growing without bound.  The
                           default (backwards compatible) value is "false".

                      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
                           default_domain = foo.se
                   }
           [logging]
                   kdc = FILE:/var/heimdal/kdc.log
                   kdc = SYSLOG:INFO
                   default = SYSLOG:INFO:USER
           [kadmin]
                   default_key_rules = {
                           */ppp@* = arcfour-hmac-md5:pw-salt
                   }

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 diagnos-
     tics 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_openlog(3), strftime(3), verify_krb5_conf(8)

HEIMDAL                           May 4, 2005                          HEIMDAL
