Provided by: heimdal-docs_7.7.0+dfsg-4ubuntu1_all bug


     krb5.conf — configuration file for Kerberos 5


     #include <krb5.h>


     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:

                   /* empty */

                   section sections

                   '[' section_name ']' bindings


                   binding bindings

                   name '=' STRING
                   name '=' '{' bindings '}'


     STRINGs consists of one or more non-whitespace characters.

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

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

                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.

                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 .

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

     Currently recognised sections and bindings are:

                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).


                      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 minutes).

                      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

                      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

                      default_keytab_name = keytab
                           The keytab to use if no other is specified, default is

                      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

                      date_format = string
                           How to print date strings in logs, this string is passed to

                      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.

                           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 provided for compatibility with MIT krb5 configuration

                      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 permissions/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 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.

                           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 (usually 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 experimental 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; currently 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 necessarily 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 setting, hierarchical
                           capaths are always used by the KDC when generating a referral to a
                           destination with which is no direct trust.

                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 “” matches
                “”, but not “”.

                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'


                      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.

                                      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

                                 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

                                 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.



                      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.



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


                      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 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

                                 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.  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, saving some entries, and keeping the latest
                                      version number so as to not disrupt incremental
                                      propagation.  If set to a negative value then automatic log
                                      truncation 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 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

                      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 certification 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 certificate 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 certificates to be
                           issued.  The following variables can be interpolated in the subject
                           name using ${variable} syntax:

                                      The full name of the kx509 client principal.

                                      The full name of the kx509 client principal, excluding the
                                      realm name.

                                      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.


                      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:


                           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

                      default_key_rules = {

                                 globing-rule = keytypes...
                                      a globbing rule to matching a principal, and when true, use
                                      the keytypes as specified the same format as
                                      [kadmin]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.

                           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,


     KRB5_CONFIG points to the configuration file to read.


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


                   default_realm = FOO.SE
                   name_canon_rules = as-is:realm=FOO.SE
                   name_canon_rules =
                   name_canon_rules =
                   name_canon_rules = nss
          = FOO.SE
          = FOO.SE
                   FOO.SE = {
                           kdc =
                           default_domain =
                   kdc = FILE:/var/heimdal/kdc.log
                   kdc = SYSLOG:INFO
                   default = SYSLOG:INFO:USER
                   default_key_rules = {
                           */ppp@* = arcfour-hmac-md5:pw-salt


     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.


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