KRB5.CONF(5) BSD File Formats Manual KRB5.CONF(5) NNAAMMEE kkrrbb55..ccoonnff -- configuration file for Kerberos 5 SSYYNNOOPPSSIISS ##iinncclluuddee <> DDEESSCCRRIIPPTTIIOONN The kkrrbb55..ccoonnff 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. _a_p_p_l_i_c_a_t_i_o_n _r_e_a_l_m _o_p_t_i_o_n 2. _a_p_p_l_i_c_a_t_i_o_n _o_p_t_i_o_n 3. _r_e_a_l_m _o_p_t_i_o_n 4. _o_p_t_i_o_n The supported options are: forwardable = _b_o_o_l_e_a_n When obtaining initial credentials, make the cre- dentials forwardable. proxiable = _b_o_o_l_e_a_n When obtaining initial credentials, make the cre- dentials proxiable. no-addresses = _b_o_o_l_e_a_n When obtaining initial credentials, request them for an empty set of addresses, making the tickets valid from any address. ticket_lifetime = _t_i_m_e Default ticket lifetime. renew_lifetime = _t_i_m_e Default renewable ticket lifetime. encrypt = _b_o_o_l_e_a_n Use encryption, when available. forward = _b_o_o_l_e_a_n Forward credentials to remote host (for rsh(1), telnet(1), etc). [libdefaults] default_realm = _R_E_A_L_M Default realm to use, this is also known as your ``local realm''. The default is the result of kkrrbb55__ggeett__hhoosstt__rreeaallmm(_l_o_c_a_l _h_o_s_t_n_a_m_e). allow_weak_crypto = _b_o_o_l_e_a_n are weak crypto algorithms allowed to be used, among others, DES is considered weak. clockskew = _t_i_m_e Maximum time differential (in seconds) allowed when comparing times. Default is 300 seconds (five min- utes). kdc_timeout = _t_i_m_e Maximum time to wait for a reply from the kdc, default is 3 seconds. capath = { _d_e_s_t_i_n_a_t_i_o_n_-_r_e_a_l_m = _n_e_x_t_-_h_o_p_-_r_e_a_l_m ... } This is deprecated, see the capaths section below. default_cc_type = _c_c_t_y_p_e sets the default credentials type. default_cc_name = _c_c_n_a_m_e 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 = _e_t_y_p_e_s _._._. 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 = _e_t_y_p_e_s _._._. A list of default encryption types to use in AS requests. (Default: the value of default_etypes.) default_tgs_etypes = _e_t_y_p_e_s _._._. A list of default encryption types to use in TGS requests. (Default: the value of default_etypes.) default_etypes_des = _e_t_y_p_e_s _._._. A list of default encryption types to use when requesting a DES credential. default_keytab_name = _k_e_y_t_a_b The keytab to use if no other is specified, default is ``FILE:/etc/krb5.keytab''. dns_lookup_kdc = _b_o_o_l_e_a_n Use DNS SRV records to lookup KDC services loca- tion. dns_lookup_realm = _b_o_o_l_e_a_n Use DNS TXT records to lookup domain to realm map- pings. kdc_timesync = _b_o_o_l_e_a_n 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 = _n_u_m_b_e_r The max number of times to try to contact each KDC. large_msg_size = _n_u_m_b_e_r The threshold where protocols with tiny maximum message sizes are not considered usable to send messages to the KDC. ticket_lifetime = _t_i_m_e Default ticket lifetime. renew_lifetime = _t_i_m_e Default renewable ticket lifetime. forwardable = _b_o_o_l_e_a_n When obtaining initial credentials, make the cre- dentials forwardable. This option is also valid in the [realms] section. proxiable = _b_o_o_l_e_a_n When obtaining initial credentials, make the cre- dentials proxiable. This option is also valid in the [realms] section. verify_ap_req_nofail = _b_o_o_l_e_a_n 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 = _t_i_m_e How soon to warn for expiring password. Default is seven days. http_proxy = _p_r_o_x_y_-_s_p_e_c A HTTP-proxy to use when talking to the KDC via HTTP. dns_proxy = _p_r_o_x_y_-_s_p_e_c Enable using DNS via HTTP. extra_addresses = _a_d_d_r_e_s_s _._._. A list of addresses to get tickets for along with all local addresses. time_format = _s_t_r_i_n_g How to print time strings in logs, this string is passed to strftime(3). date_format = _s_t_r_i_n_g How to print date strings in logs, this string is passed to strftime(3). log_utc = _b_o_o_l_e_a_n Write log-entries using UTC instead of your local time zone. scan_interfaces = _b_o_o_l_e_a_n Scan all network interfaces for addresses, as opposed to simply using the address associated with the system's host name. fcache_version = _i_n_t Use file credential cache format version specified. fcc-mit-ticketflags = _b_o_o_l_e_a_n 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 = _d_i_r_e_c_t_o_r_y Alternative location for user .k5login files. This option is provided for compatibility with MIT krb5 configuration files. k5login_authoritative = _b_o_o_l_e_a_n 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 = _r_u_l_e _._._. 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 = _D_E_N_Y If set and evaluated then krb5_userok(3) will deny access to the given username no matter what the principal name might be. kuserok = _S_I_M_P_L_E 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 = _S_Y_S_T_E_M_-_K_5_L_O_G_I_N_[_:_d_i_r_e_c_t_o_r_y_] If set and evaluated then krb5_userok(3) will use k5login files named after the _l_u_s_e_r argument to krb5_userok(3) in the given directory or in _/_e_t_c_/_k_5_l_o_g_i_n_._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 = _U_S_E_R_-_K_5_L_O_G_I_N If set and evaluated then krb5_userok(3) will use _~_l_u_s_e_r_/_._k_5_l_o_g_i_n and _~_l_u_s_e_r_/_._k_5_l_o_g_i_n_._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 = _f_i_l_e_n_a_m_e 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 = _r_u_l_e_s 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: _a_s_-_i_s_, _q_u_a_l_i_f_y_, _o_r _n_s_s_. Any remaining tokens must be options tokens: _u_s_e___f_a_s_t (use FAST to protect TGS exchanges; cur- rently not supported), _u_s_e___d_n_s_s_e_c (use DNSSEC to protect hostname lookups; currently not supported), _c_c_a_c_h_e___o_n_l_y , _u_s_e___r_e_f_e_r_r_a_l_s_, _n_o___r_e_f_e_r_r_a_l_s_, _l_o_o_k_u_p___r_e_a_l_m_, _m_i_n_d_o_t_s_=_N_, _m_a_x_d_o_t_s_=_N_, _o_r_d_e_r_=_N_, domain= _d_o_m_a_i_n_, realm= _r_e_a_l_m_, match_domain= _d_o_m_a_i_n_, and match_realm= _r_e_a_l_m_. 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 _m_i_n_d_o_t_s periods (if given) in it, at most _m_a_x_d_o_t_s periods (if given), that the hostname ends in the given _m_a_t_c_h___d_o_m_a_i_n (if given), and that the realm of the principal matches the _m_a_t_c_h___r_e_a_l_m (if given). _A_s_-_i_s rules leave the hostname unmodified but may set a realm. _Q_u_a_l_i_f_y rules qualify the hostname with the given _d_o_m_a_i_n and also may set the realm. The _n_s_s rule uses the system resolver to lookup the host's canonical name and is usually not secure. Note that using the _n_s_s 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 _o_r_d_e_r then all other rules in the order in which they appear. If any two rules have the same explicit _o_r_d_e_r, 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 = _b_o_o_l_e_a_n 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] _R_E_A_L_M = { kdc = _[_s_e_r_v_i_c_e_/_]_h_o_s_t_[_:_p_o_r_t_] Specifies a list of kdcs for this realm. If the optional _p_o_r_t 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 _s_e_r_v_i_c_e 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 = _h_o_s_t_[_:_p_o_r_t_] Specifies the admin server for this realm, where all the modifications to the database are performed. kpasswd_server = _h_o_s_t_[_:_p_o_r_t_] 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 = { _p_r_i_n_c_i_p_a_l___n_a_m_e _= _u_s_e_r_n_a_m_e The given _p_r_i_n_c_i_p_a_l___n_a_m_e will be mapped to the given _u_s_e_r_n_a_m_e if the _R_E_A_L_M is a default realm. } auth_to_local = HEIMDAL_DEFAULT Use the Heimdal default principal to username mapping. Applies to principals from the _R_E_A_L_M if and only if _R_E_A_L_M is a default realm. auth_to_local = DEFAULT Use the MIT default principal to user- name mapping. Applies to principals from the _R_E_A_L_M if and only if _R_E_A_L_M 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 _R_E_A_L_M if and only if _R_E_A_L_M 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 _R_E_A_L_M if and only if _R_E_A_L_M is a default realm. auth_to_local = RULE:... Use the given rule, if there's a plugin for it. Applies to principals from the _R_E_A_L_M if and only if _R_E_A_L_M is a default realm. auth_to_local = NONE No additional principal to username map- ping is done. Note that _a_u_t_h___t_o___l_o_c_a_l___n_a_m_e_s and any preceding _a_u_t_h___t_o___l_o_c_a_l rules have precedence. } [capaths] _c_l_i_e_n_t_-_r_e_a_l_m = { _s_e_r_v_e_r_-_r_e_a_l_m = _h_o_p_-_r_e_a_l_m _._._. This serves two purposes. First the first listed _h_o_p_-_r_e_a_l_m tells a client which realm it should contact in order to ultimately obtain credentials for a service in the _s_e_r_v_e_r_-_r_e_a_l_m. Secondly, it tells the KDC (and other servers) which realms are allowed in a multi-hop traversal from _c_l_i_e_n_t_-_r_e_a_l_m to _s_e_r_v_e_r_-_r_e_a_l_m. Except for the client case, the order of the realms are not important. _} [logging] _e_n_t_i_t_y = _d_e_s_t_i_n_a_t_i_o_n Specifies that _e_n_t_i_t_y should use the specified destination for logging. See the krb5_openlog(3) manual page for a list of defined destinations. [kdc] database = { dbname = _[_D_A_T_B_A_S_E_T_Y_P_E_:_]_D_A_T_A_B_A_S_E_N_A_M_E Use this database for this realm. The _D_A_T_A_B_A_S_E_T_Y_P_E should be one of 'lmdb', 'db3', 'db1', 'db', 'sqlite', or 'ldap'. See the info documetation how to config- ure different database backends. realm = _R_E_A_L_M 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 = _F_I_L_E_N_A_M_E Use this keytab file for the master key of this database. If not specified _D_A_T_A_B_A_S_E_N_A_M_E.mkey will be used. acl_file = PA FILENAME Use this file for the ACL list of this database. log_file = _F_I_L_E_N_A_M_E Use this file as the log of changes per- formed to the database. This file is used by iipprrooppdd--mmaasstteerr for propagating changes to slaves. It is also used by kkaaddmmiinndd and kkaaddmmiinn (when used with the -l option), and by all applications using lliibbkkaaddmm55 with the local backend, for two-phase commit functionality. Slaves also use this. Setting this to //ddeevv//nnuullll disables two-phase commit and incremental propagation. Use iipprroopp--lloogg to show the contents of this log file. log-max-size = _n_u_m_b_e_r 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 = _S_I_Z_E Maximum size of a kdc request. require-preauth = _B_O_O_L If set pre-authentication is required. ports = _l_i_s_t _o_f _p_o_r_t_s List of ports the kdc should listen to. addresses = _l_i_s_t _o_f _i_n_t_e_r_f_a_c_e_s List of addresses the kdc should bind to. enable-http = _B_O_O_L Should the kdc answer kdc-requests over http. tgt-use-strongest-session-key = _B_O_O_L 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 = _B_O_O_L 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 = _B_O_O_L 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 = _B_O_O_L 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 = _B_O_O_L Verify the addresses in the tickets used in tgs requests. allow-null-ticket-addresses = _B_O_O_L Allow address-less tickets. allow-anonymous = _B_O_O_L If the kdc is allowed to hand out anonymous tick- ets. encode_as_rep_as_tgs_rep = _B_O_O_L Encode as-rep as tgs-rep tobe compatible with mis- takes older DCE secd did. kdc_warn_pwexpire = _T_I_M_E The time before expiration that the user should be warned that her password is about to expire. logging = _L_o_g_g_i_n_g What type of logging the kdc should use, see also [logging]/kdc. hdb-ldap-structural-object _s_t_r_u_c_t_u_r_a_l _o_b_j_e_c_t 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 _c_r_e_a_t_i_o_n _d_n is the dn that will be appended to the principal when creating entries. Default value is the search dn. enable-digest = _B_O_O_L Should the kdc answer digest requests. The default is FALSE. digests_allowed = _l_i_s_t _o_f _d_i_g_e_s_t_s Specifies the digests the kdc will reply to. The default is ntlm-v2. kx509_ca = _f_i_l_e Specifies the PEM credentials for the kx509 certi- fication authority. require_initial_kca_tickets = _b_o_o_l_e_a_n 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 = _b_o_o_l_e_a_n 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 = _f_i_l_e 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 = _t_i_m_e If a principal already have its password set for expiration, this is the time it will be valid for after a change. default_keys = _k_e_y_t_y_p_e_s_._._. For each entry in _d_e_f_a_u_l_t___k_e_y_s try to parse it as a sequence of _e_t_y_p_e_:_s_a_l_t_t_y_p_e_:_s_a_l_t syntax of this if something like: [(des|des3|etype):](pw-salt|afs3-salt)[:string] If _e_t_y_p_e 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 _p_w_-_s_a_l_t default_key_rules = _{ _g_l_o_b_i_n_g_-_r_u_l_e = _k_e_y_t_y_p_e_s_._._. 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 = _B_O_O_L 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 = _B_O_O_L When true, this is the same as _d_e_f_a_u_l_t___k_e_y_s _= _d_e_s_3_:_p_w_-_s_a_l_t _v_4 and is only left for backwards compatibility. [password_quality] Check the Password quality assurance in the info documentation for more information. check_library = _l_i_b_r_a_r_y_-_n_a_m_e Library name that contains the password check_function check_function = _f_u_n_c_t_i_o_n_-_n_a_m_e Function name for checking passwords in check_library policy_libraries = _l_i_b_r_a_r_y_1 _._._. _l_i_b_r_a_r_y_N List of libraries that can do password policy checks policies = _p_o_l_i_c_y_1 _._._. _p_o_l_i_c_y_N List of policy names to apply to the password. Builtin policies are among other minimum-length, character-class, external-check. EENNVVIIRROONNMMEENNTT KRB5_CONFIG points to the configuration file to read. FFIILLEESS /etc/krb5.conf configuration file for Kerberos 5. EEXXAAMMPPLLEESS [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 } DDIIAAGGNNOOSSTTIICCSS Since kkrrbb55..ccoonnff 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 vveerriiffyy__kkrrbb55__ccoonnff that reads kkrrbb55..ccoonnff 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. SSEEEE AALLSSOO kinit(1), krb5_openlog(3), strftime(3), verify_krb5_conf(8) HEIMDAL May 4, 2005 HEIMDAL