bionic (5) krb5.conf.5heimdal.gz

Provided by: heimdal-docs_7.5.0+dfsg-1ubuntu0.4_all bug

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
                           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 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.

                      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 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/.  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.

                      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 (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.

           [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.

                                 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 = [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 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.  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 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 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:

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

                                 principal-name-without-realm
                                      The full name of the kx509 client principal, 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).  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.

                      [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 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_openlog(3), strftime(3), verify_krb5_conf(8)