1 .TH "KRB5.CONF" "5" "January 06, 2012" "0.0.1" "MIT Kerberos"
3 krb5.conf \- Kerberos configuration file
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34 The krb5.conf file contains Kerberos configuration information, including the locations of KDCs and admin servers for the Kerberos realms of interest, defaults for the current realm and for Kerberos applications, and mappings of hostnames onto Kerberos realms. Normally, you should install your krb5.conf file in the directory /etc. You can override the default location by setting the environment variable KRB5_CONFIG.
37 The krb5.conf file is set up in the style of a Windows INI file. Sections are headed by the section name, in square brackets. Each section may contain zero or more relations, of the form:
56 Placing a \(aq*\(aq at the end of a line indicates that this is the \fIfinal\fP value for the tag. This means that neither the remainder of this configuration file nor any other configuration file will be checked for any other values for this tag.
58 For example, if you have the following lines:
67 then the second value of \fIfoo\fP (baz) would never be read.
69 The krb5.conf file can include other files using either of the following directives at the beginning of a line:
78 \fIFILENAME\fP or \fIDIRNAME\fP should be an absolute path. The named file or directory must exist and be readable. Including a directory includes all files within the directory whose names consist solely of alphanumeric characters, dashes, or underscores. Included profile files are syntactically independent of their parents, so each included file must begin with a section header.
80 The krb5.conf file can specify that configuration should be obtained from a loadable module, rather than the file itself, using the following directive at the beginning of a line before any section headers:
84 module MODULEPATH:RESIDUAL
88 \fIMODULEPATH\fP may be relative to the library path of the krb5 installation, or it may be an absolute path. \fIRESIDUAL\fP is provided to the module at initialization time. If krb5.conf uses a module directive, kdc.conf should also use one if it exists.
90 The krb5.conf file may contain any or all of the following sections:
98 Contains default values used by the Kerberos V5 library.
104 Contains subsections keyed by Kerberos realm names. Each subsection describes realm\-specific information, including where to find the Kerberos servers for that realm.
110 Contains relations which map domain names and subdomains onto Kerberos realm names. This is used by programs to determine what realm a host should be in, given its fully qualified domain name.
116 Contains relations which determine how Kerberos programs are to perform logging.
122 Contains the authentication paths used with direct (nonhierarchical) cross\-realm authentication. Entries in this section are used by the client to determine the intermediate realms which may be used in cross\-realm authentication. It is also used by the end\-service when checking the transited field for trusted intermediate realms.
128 Contains tags to register dynamic plugin modules and to turn modules on and off.
134 Contains default values that can be used by Kerberos V5 applications.
139 .SS \fB[libdefaults]\fP
141 The libdefaults section may contain any of the following relations:
144 .B \fBallow_weak_crypto\fP
146 If this is set to 0 (for false), then weak encryption types will be filtered out of the previous three lists (as noted in \fISupported_Encryption_Types_and_Salts\fP). The default value for this tag is false, which may cause authentication failures in existing Kerberos infrastructures that do not support strong crypto. Users in affected environments should set this tag to true until their infrastructure adopts stronger ciphers.
148 .B \fBap_req_checksum_type\fP
150 An integer which specifies the type of AP\-REQ checksum to use in authenticators.
151 This variable should be unset so the appropriate checksum for the encryption key in use will be used.
152 This can be set if backward compatibility requires a specific checksum type.
153 See the \fIkdc_req_checksum_type\fP configuration option for the possible values and their meanings.
155 .B \fBcanonicalize\fP
157 This flag indicates to the KDC that the client is prepared to receive a reply that contains a principal name other than the one requested.
158 The client should expect, when sending names with the "canonicalize" KDC option,
159 that names in the KDC\(aqs reply will be different than the name in the request.
160 The default value for this flag is not set.
164 Use this parameter on systems which are DCE clients, to specify the type of cache to be created by kinit, or when forwarded tickets are received. DCE and Kerberos can share the cache, but some versions of DCE do not support the default cache as created by this version of Kerberos. Use a value of 1 on DCE 1.0.3a systems, and a value of 2 on DCE 1.1 systems. The default value is 4.
168 Sets the maximum allowable amount of clockskew in seconds that the library will tolerate before assuming that a Kerberos message is invalid. The default value is 300 seconds, or five minutes.
170 .B \fBdefault_keytab_name\fP
172 This relation specifies the default keytab name to be used by application servers such as telnetd and rlogind. The default is \fI/etc/krb5.keytab\fP.
174 .B \fBdefault_realm\fP
176 Identifies the default Kerberos realm for the client. Set its value to your Kerberos realm. If this is not specified and the TXT record lookup is enabled (see \fIudns_label\fP), then that information will be used to determine the default realm. If this tag is not set in this configuration file and there is no DNS information found, then an error will be returned.
178 .B \fBdefault_tgs_enctypes\fP
180 Identifies the supported list of session key encryption types that should be returned by the KDC. The list may be delimited with commas or whitespace. Kerberos supports many different encryption types, and support for more is planned in the future. (see \fISupported_Encryption_Types_and_Salts\fP for a list of the accepted values for this tag). The default value is \fIaes256\-cts\-hmac\-sha1\-96 aes128\-cts\-hmac\-sha1\-96 des3\-cbc\-sha1 arcfour\-hmac\-md5 des\-cbc\-crc des\-cbc\-md5 des\-cbc\-md4\fP.
182 .B \fBdefault_tkt_enctypes\fP
184 Identifies the supported list of session key encryption types that should be requested by the client. The format is the same as for default_tgs_enctypes. The default value for this tag is \fIaes256\-cts\-hmac\-sha1\-96 aes128\-cts\-hmac\-sha1\-96 des3\-cbc\-sha1 arcfour\-hmac\-md5 des\-cbc\-crc des\-cbc\-md5 des\-cbc\-md4\fP.
186 .B \fBdns_fallback\fP
188 General flag controlling the use of DNS for Kerberos information. If both of the preceding options are specified, this option has no effect.
190 .B \fBdns_lookup_kdc\fP
192 Indicate whether DNS SRV records should be used to locate the KDCs and other servers for a realm, if they are not listed in the information for the realm. (Note that the admin_server entry must be in the file, because the DNS implementation for it is incomplete.)
194 Enabling this option does open up a type of denial\-of\-service attack, if someone spoofs the DNS records and redirects you to another server. However, it\(aqs no worse than a denial of service, because that fake KDC will be unable to decode anything you send it (besides the initial ticket request, which has no encrypted data), and anything the fake KDC sends will not be trusted without verification using some secret that it won\(aqt know.
196 If this option is not specified but dns_fallback is, that value will be used instead. If neither option is specified, the behavior depends on configure\-time options; if none were given, the default is to enable this option. If the DNS support is not compiled in, this entry has no effect.
198 .B \fBdns_lookup_realm\fP
200 Indicate whether DNS TXT records should be used to determine the Kerberos realm of a host.
202 Enabling this option may permit a redirection attack, where spoofed DNS replies persuade a client to authenticate to the wrong realm, when talking to the wrong host (either by spoofing yet more DNS records or by intercepting the net traffic). Depending on how the client software manages hostnames, however, it could already be vulnerable to such attacks. We are looking at possible ways to minimize or eliminate this exposure. For now, we encourage more adventurous sites to try using Secure DNS.
204 If this option is not specified but dns_fallback is, that value will be used instead. If neither option is specified, the behavior depends on configure\-time options; if none were given, the default is to disable this option. If the DNS support is not compiled in, this entry has no effect.
206 .B \fBextra_addresses\fP
208 This allows a computer to use multiple local addresses, in order to allow Kerberos to work in a network that uses NATs. The addresses should be in a comma\-separated list.
212 If this flag is set, initial tickets by default will be forwardable. The default value for this flag is not set.
214 .B \fBignore_acceptor_hostname\fP
216 When accepting GSSAPI or krb5 security contexts for host\-based service principals,
217 ignore any hostname passed by the calling application and allow any service principal present in the keytab
218 which matches the service name and realm name (if given).
219 This option can improve the administrative flexibility of server applications on multihomed hosts,
220 but can compromise the security of virtual hosting environments. The default value is false.
222 .B \fBk5login_authoritative\fP
224 If the value of this relation is true (the default), principals must be listed in a local user\(aqs k5login file to be granted login access, if a k5login file exists. If the value of this relation is false, a principal may still be granted login access through other mechanisms even if a k5login file exists but does not list the principal.
226 .B \fBk5login_directory\fP
228 If set, the library will look for a local user\(aqs k5login file within the named directory, with a filename corresponding to the local username. If not set, the library will look for k5login files in the user\(aqs home directory, with the filename .k5login. For security reasons, k5login files must be owned by the local user or by root.
230 .B \fBkdc_default_options\fP
232 Default KDC options (Xored for multiple values) when requesting initial credentials. By default it is set to 0x00000010 (KDC_OPT_RENEWABLE_OK).
234 .B \fBkdc_timesync\fP
236 If this is set to 1 (for true), then client machines will compute the difference between their time and the time returned by the KDC in the timestamps in the tickets and use this value to correct for an inaccurate system clock. This corrective factor is only used by the Kerberos library. The default is 1.
238 .B \fBkdc_req_checksum_type\fP
240 An integer which specifies the type of checksum to use for the KDC requests for compatibility with DCE security servers
241 which do not support the default RSA MD5 used by Kerberos V5.
242 This applies to DCE 1.1 and earlier.
243 Use a value of 2 to use the RSA MD4 instead.
244 This value is only used for DES keys; other keys use the preferred checksum type for those keys.
246 The possible values and their meanings are as follows.
302 Microsoft MD5 HMAC checksum type
309 Setting this flag causes the initial Kerberos ticket to be addressless. The default for the flag is set.
311 .B \fBpermitted_enctypes\fP
313 Identifies all encryption types that are permitted for use in session key encryption. The default value for this tag is \fIaes256\-cts\-hmac\-sha1\-96 aes128\-cts\-hmac\-sha1\-96 des3\-cbc\-sha1 arcfour\-hmac\-md5 des\-cbc\-crc des\-cbc\-md5 des\-cbc\-md4\fP.
315 .B \fBplugin_base_dir\fP
317 If set, determines the base directory where krb5 plugins are located.
318 The default value is the "krb5/plugins" subdirectory of the krb5 library directory.
320 .B \fBpreferred_preauth_types\fP
322 This allows you to set the preferred preauthentication types which the client will attempt before others which may be advertised by a KDC. The default value for this setting is "17, 16, 15, 14", which forces libkrb5 to attempt to use PKINIT if it is supported.
326 If this flag is set, initial tickets by default will be proxiable. The default value for this flag is not set.
330 If set to false, prevent the use of reverse DNS resolution when translating hostnames into service principal names. Defaults to true. Setting this flag to false is more secure, but may force users to exclusively use fully qualified domain names when authenticating to services.
332 .B \fBrealm_try_domains\fP
334 Indicate whether a host\(aqs domain components should be used to determine the Kerberos realm of the host. The value of this variable is an integer: \-1 means not to search, 0 means to try the host\(aqs domain itself, 1 means to also try the domain\(aqs immediate parent, and so forth. The library\(aqs usual mechanism for locating Kerberos realms is used to determine whether a domain is a valid realm\-\-which may involve consulting DNS if \fIdns_lookup_kdc\fP is set. The default is not to search domain components.
336 .B \fBrenew_lifetime\fP
338 The value of this tag is the default renewable lifetime for initial tickets. The default value for the tag is 0.
341 \fBsafe_checksum_type\fP
345 An integer which specifies the type of checksum to use for the KRB\-SAFE requests. By default it is set to 8 (RSA MD5 DES).
346 For compatibility with applications linked against DCE version 1.1 or earlier Kerberos libraries,
347 use a value of 3 to use the RSA MD4 DES instead.
348 This field is ignored when its value is incompatible with the session key type.
349 See the \fIkdc_req_checksum_type\fP configuration option for the possible values and their meanings.
354 .B \fBticket_lifetime\fP
356 The value of this tag is the default lifetime for initial tickets. The default value for the tag is 1 day.
358 .B \fBudp_preference_limit\fP
360 When sending a message to the KDC, the library will try using TCP before UDP if the size of the message is above \fIudp_preference_list\fP. If the message is smaller than \fIudp_preference_list\fP, then UDP will be tried before TCP. Regardless of the size, both protocols will be tried if the first attempt fails.
362 .B \fBverify_ap_req_nofail\fP
364 If this flag is set, then an attempt to get initial credentials will fail if the client machine does not have a keytab. The default for the flag is not set.
368 Each tag in the [realms] section of the file is the name of a Kerberos realm. The value of the tag is a subsection with relations that define the properties of that particular realm. For each realm, the following tags may be specified in the realm\(aqs subsection:
371 .B \fBadmin_server\fP
373 Identifies the host where the administration server is running. Typically, this is the master Kerberos server. This tag must be given a value in order to communicate with the kadmin server for the realm.
375 .B \fBauth_to_local\fP
377 This tag allows you to set a general rule for mapping principal names to local user names. It will be used if there is not an explicit mapping for the principal name that is being translated. The possible values are:
382 The principal will be looked up in the database filename. Support for this is not currently compiled in by default.
386 The local name will be formulated from exp.
388 The format for exp is [n:string](regexp)s/pattern/replacement/g. The integer n indicates how many components the target principal should have. If this matches, then a string will be formed from string, substituting the realm of the principal for $0 and the n\(aqth component of the principal for $n (e.g. if the principal was \fIjohndoe/admin\fP then [2:$2$1foo] would result in the string "adminjohndoefoo"). If this string matches regexp, then the s//[g] substitution command will be run over the string. The optional g will cause the substitution to be global over the string, instead of replacing only the first match in the string.
392 The principal name will be used as the local user name. If the principal has more than one component or is not in the default realm, this rule is not applicable and the conversion will fail.
401 auth_to_local = RULE:[2:$1](johndoe)s/^.*$/guest/
402 auth_to_local = RULE:[2:$1;$2](^.*;admin$)s/;admin$//
403 auth_to_local = RULE:[2:$2](^.*;root)s/^.*$/root/
404 auto_to_local = DEFAULT
409 would result in any principal without \fIroot\fP or \fIadmin\fP as the second component to be translated with the default rule. A principal with a second component of \fIadmin\fP will become its first component. \fIroot\fP will be used as the local name for any principal with a second component of \fIroot\fP. The exception to these two rules are any principals \fIjohndoe\fP/*, which will always get the local name \fIguest\fP.
411 .B \fBauth_to_local_names\fP
413 This subsection allows you to set explicit mappings from principal names to local user names. The tag is the mapping name, and the value is the corresponding local user name.
415 .B \fBdatabase_module\fP
417 This relation indicates the name of the configuration section under [dbmodules] for database specific parameters used by the loadable database library.
419 .B \fBdefault_domain\fP
421 This tag is used for Kerberos 4 compatibility. Kerberos 4 does not require the entire hostname of a server to be in its principal like Kerberos 5 does. This tag provides the domain name needed to produce a full hostname when translating V4 principal names into V5 principal names. All servers in this realm are assumed to be in the domain given as the value of this tag
425 The name or address of a host running a KDC for that realm. An optional port number, separated from the hostname by a colon, may be included. If the name or address contains colons (for example, if it is an IPv6 address), enclose it in square brackets to distinguish the colon from a port separator. For your computer to be able to communicate with the KDC for each realm, this tag must be given a value in each realm subsection in the configuration file, or there must be DNS SRV records specifying the KDCs (see \fIudns_label\fP).
427 .B \fBkpasswd_server\fP
429 Points to the server where all the password changes are performed. If there is no such entry, the port 464 on the \fIadmin_server\fP host will be tried.
431 .B \fBkrb524_server\fP
433 Points to the server that does 524 conversions. If it is not mentioned, the krb524 port 4444 on the kdc will be tried.
437 Identifies the master KDC(s). Currently, this tag is used in only one case: If an attempt to get credentials fails because of an invalid password, the client software will attempt to contact the master KDC, in case the user\(aqs password has just been changed, and the updated database has not been propagated to the slave servers yet.
439 .B \fBv4_instance_convert\fP
441 This subsection allows the administrator to configure exceptions to the default_domain mapping rule. It contains V4 instances (the tag name) which should be translated to some specific hostname (the tag value) as the second component in a Kerberos V5 principal name.
445 This relation is used by the krb524 library routines when converting a V5 principal name to a V4 principal name. It is used when the V4 realm name and the V5 realm name are not the same, but still share the same principal names and passwords. The tag value is the Kerberos V4 realm name.
447 .SS \fB[domain_realm]\fP
449 The [domain_realm] section provides a translation from a domain name or hostname to a Kerberos realm name. The tag name can be a host name, or a domain name, where domain names are indicated by a prefix of a period (.). The value of the relation is the Kerberos realm name for that particular host or domain. Host names and domain names should be in lower case.
451 If no translation entry applies, the host\(aqs realm is considered to be the hostname\(aqs domain portion converted to upper case. For example, the following [domain_realm] section:
456 crash.mit.edu = TEST.ATHENA.MIT.EDU
457 .mit.edu = ATHENA.MIT.EDU
458 mit.edu = ATHENA.MIT.EDU
459 example.com = EXAMPLE.COM
463 maps the host with the \fIexact\fP name \fIcrash.mit.edu\fP into the TEST.ATHENA.MIT.EDU realm. The period prefix in \fI.mit.edu\fP denotes that \fIall\fP systems in the \fImit.edu\fP domain belong to ATHENA.MIT.EDU realm.
464 Note the entries for the hosts \fImit.edu\fP and \fIexample.com\fP. Without these entries, these hosts would be mapped into the Kerberos realms EDU and COM, respectively.
467 The [logging] section indicates how a particular entity is to perform its logging. The relations in this section assign one or more values to the entity name. Currently, the following entities are used:
470 .B \fBadmin_server\fP
472 These entries specify how the administrative server is to perform its logging.
476 These entries specify how to perform logging in the absence of explicit specifications otherwise.
480 These entries specify how the KDC is to perform its logging.
483 Values are of the following forms:
492 This value causes the entity\(aqs logging messages to go to the specified file. If the = form is used, the file is overwritten. If the : form is used, the file is appended to.
499 This value causes the entity\(aqs logging messages to go to its standard error stream.
503 This value causes the entity\(aqs logging messages to go to the console, if the system supports it.
505 .B DEVICE=<devicename>
507 This causes the entity\(aqs logging messages to go to the specified device.
509 .B SYSLOG[:<severity>[:<facility>]]
511 This causes the entity\(aqs logging messages to go to the system log.
513 The severity argument specifies the default severity of system log messages. This may be any of the following severities supported by the syslog(3) call, minus the LOG_ prefix: LOG_EMERG, LOG_ALERT, LOG_CRIT, LOG_ERR, LOG_WARNING, LOG_NOTICE, LOG_INFO, and LOG_DEBUG. For example, a value of CRIT would specify LOG_CRIT severity.
515 The facility argument specifies the facility under which the messages are logged. This may be any of the following facilities supported by the syslog(3) call minus the LOG_ prefix: LOG_KERN, LOG_USER, LOG_MAIL, LOG_DAEMON, LOG_AUTH, LOG_LPR, LOG_NEWS, LOG_UUCP, LOG_CRON, and LOG_LOCAL0 through LOG_LOCAL7.
517 If no severity is specified, the default is ERR. If no facility is specified, the default is AUTH.
520 In the following example, the logging messages from the KDC will go to the console and to the system log under the facility LOG_DAEMON with default severity of LOG_INFO; and the logging messages from the administrative server will be appended to the file \fI/var/adm/kadmin.log\fP and sent to the device \fI/dev/tty04\fP.:
526 kdc = SYSLOG:INFO:DAEMON
527 admin_server = FILE:/var/adm/kadmin.log
528 admin_server = DEVICE=/dev/tty04
533 In order to perform direct (non\-hierarchical) cross\-realm authentication, a database is needed to construct the authentication paths between the realms. This section defines that database.
535 A client will use this section to find the authentication path between its realm and the realm of the server. The server will use this section to verify the authentication path used by the client, by checking the transited field of the received ticket.
537 There is a tag for each participating realm, and each tag has subtags for each of the realms. The value of the subtags is an intermediate realm which may participate in the cross\-realm authentication. The subtags may be repeated if there is more then one intermediate realm. A value of "." means that the two realms share keys directly, and no intermediate realms should be allowed to participate.
539 There are n**2 possible entries in this table, but only those entries which will be needed on the client or the server need to be present. The client needs a tag for its local realm, with subtags for all the realms of servers it will need to authenticate with. A server needs a tag for each realm of the clients it will serve.
541 For example, \fIANL.GOV, PNL.GOV\fP, and \fINERSC.GOV\fP all wish to use the \fIES.NET\fP realm as an intermediate realm. \fIANL\fP has a sub realm of \fITEST.ANL.GOV\fP which will authenticate with \fINERSC.GOV\fP but not \fIPNL.GOV\fP. The [capaths] section for \fIANL.GOV\fP systems would look like this:
567 The [capaths] section of the configuration file used on \fINERSC.GOV\fP systems would look like this:
574 TEST.ANL.GOV = ES.NET
575 TEST.ANL.GOV = ANL.GOV
595 In the above examples, the ordering is not important, except when the same subtag name is used more then once. The client will use this to determine the path. (It is not important to the server, since the transited field is not sorted.)
597 This feature is not currently supported by DCE. DCE security servers can be used with Kerberized clients and servers, but versions prior to DCE 1.1 did not fill in the transited field, and should be used with caution.
598 .SS \fB[dbdefaults]\fP
600 The [dbdefaults] section provides default values for the database specific parameters. It can also specify the configuration section under \fI\%dbmodules\fP section for database specific parameters used by the database library.
602 The following tags are used in this section:
605 .B \fBdatabase_module\fP
607 This relation indicates the name of the configuration section under the \fI\%dbmodules\fP for database specific parameters used by the loadable database library.
609 .B \fBldap_kerberos_container_dn\fP
611 This LDAP specific tag indicates the DN of the container object where the realm objects will be located. This value is used if the container object is not mentioned in the configuration section under \fI\%dbmodules\fP.
615 This LDAP specific tag indicates the default bind DN for the KDC server. The KDC server does a login to the directory as this object. This object should have the rights to read the Kerberos data in the LDAP database. This value is used if the bind DN for the KDC is not mentioned in the configuration section under \fI\%dbmodules\fP.
617 .B \fBldap_kadmind_dn\fP
619 This LDAP specific tag indicates the default bind DN for the Administration server. The administration server does a login to the directory as this object. This object should have the rights to read and write the Kerberos data in the LDAP database. This value is used if the bind DN for the Administration server is not mentioned in the configuration section under \fI\%dbmodules\fP.
621 .B \fBldap_service_password_file\fP
623 This LDAP specific tag indicates the file containing the stashed passwords (created by kdb5_ldap_util stashsrvpw) for the objects used by the Kerberos servers to bind to the LDAP server. This file must be kept secure. This value is used if no service password file is mentioned in the configuration section under \fI\%dbmodules\fP.
625 .B \fBldap_servers\fP
627 This LDAP specific tag indicates the list of LDAP servers that the Kerberos servers can connect to. The list of LDAP servers is whitespace\-separated. The LDAP server is specified by a LDAP URI. This value is used if no LDAP servers are mentioned in the configuration section under \fI\%dbmodules\fP. It is recommended to use the \fIldapi://\fP or \fIldaps://\fP interface and not to use \fIldap://\fP interface.
629 .B \fBldap_conns_per_server\fP
631 This LDAP specific tag indicates the number of connections to be maintained per LDAP server. This value is used if the number of connections per LDAP server are not mentioned in the configuration section under \fI\%dbmodules\fP. The default value is 5.
633 .SS \fB[dbmodules]\fP
635 Contains database specific parameters used by the database library. Each tag in the [dbmodules] section of the file names a configuration section for database specific parameters that can be referred to by a realm. The value of the tag is a subsection where the relations in that subsection define the database specific parameters.
637 For each section, the following tags may be specified in the subsection:
640 .B \fBdatabase_name\fP
642 This DB2\-specific tag indicates the location of the database in the filesystem. The default is \fI/usr/local/var/krb5kdc/principal\fP.
646 This tag indicates the name of the loadable database library. The value should be \fIdb2\fP for DB2 database and \fIkldap\fP for LDAP database.
648 .B \fBdb_module_dir\fP
650 This tag controls where the plugin system looks for modules. The value should be an absolute path.
652 .B \fBdisable_last_success\fP
654 If set to \fItrue\fP, suppresses KDC updates to the \fI"Last successful authentication"\fP field of principal entries requiring preauthentication. Setting this flag may improve performance. (Principal entries which do not require preauthentication never update the "Last successful authentication" field.).
656 .B \fBdisable_lockout\fP
658 If set to \fItrue\fP, suppresses KDC updates to the \fI"Last failed authentication"\fP and \fI"Failed password attempts"\fP fields of principal entries requiring preauthentication. Setting this flag may improve performance, but also disables account lockout.
660 .B \fBldap_conns_per_server\fP
662 This LDAP specific tags indicates the number of connections to be maintained per LDAP server.
664 .B \fBldap_kadmind_dn\fP
666 This LDAP specific tag indicates the default bind DN for the Administration server. The administration server does a login to the directory as this object. This object should have the rights to read and write the Kerberos data in the LDAP database.
670 This LDAP specific tag indicates the default bind DN for the KDC server. The KDC server does a login to the directory as this object. This object should have the rights to read the Kerberos data in the LDAP database.
672 .B \fBldap_kerberos_container_dn\fP
674 This LDAP specific tag indicates the DN of the container object where the realm objects will be located.
676 .B \fBldap_servers\fP
678 This LDAP specific tag indicates the list of LDAP servers that the Kerberos servers can connect to. The list of LDAP servers is whitespace\-separated. The LDAP server is specified by a LDAP URI. It is recommended to use \fIldapi://\fP or \fIldaps://\fP interface to connect to the LDAP server.
680 .B \fBldap_service_password_file\fP
682 This LDAP specific tag indicates the file containing the stashed passwords (created by \fIkdb5_ldap_util stashsrvpw\fP) for the objects used by the Kerberos servers to bind to the LDAP server. This file must be kept secure.
684 .SS \fB[appdefaults]\fP
686 Each tag in the [appdefaults] section names a Kerberos V5 application or an option that is used by some Kerberos V5 application[s]. The value of the tag defines the default behaviors for that application.
709 The above four ways of specifying the value of an option are shown in order of decreasing precedence. In this example, if telnet is running in the realm EXAMPLE.COM, it should, by default, have option1 and option2 set to true. However, a telnet program in the realm ATHENA.MIT.EDU should have option1 set to false and option2 set to true. Any other programs in ATHENA.MIT.EDU should have option2 set to false by default. Any programs running in other realms should have option2 set to true.
711 The list of specifiable options for each application may be found in that application\(aqs man pages. The application defaults specified here are overridden by those specified in the \fI\%realms\fP section.
718 \fI\%pwqual\fP interface
721 \fI\%kadm5_hook\fP interface
724 \fI\%clpreauth\fP and \fI\%kdcpreauth\fP interfaces
729 Tags in the \fB[plugins]\fP section can be used to register dynamic plugin modules and to turn modules on and off. Not every krb5 pluggable interface uses the [plugins] section; the ones that do are documented here.
731 Each pluggable interface corresponds to a subsection of [plugins]. All subsections support the same tags:
736 This tag may have multiple values. If there are values for this tag, then the named modules will be disabled for the pluggable interface.
740 This tag may have multiple values. If there are values for this tag, then only the named modules will be enabled for the pluggable interface.
744 This tag may have multiple values. Each value is a string of the form "modulename:pathname", which causes the shared object located at pathname to be registered as a dynamic module named modulename for the pluggable interface. If pathname is not an absolute path, it will be treated as relative to the "krb5/plugins" subdirectory of the krb5 library directory.
747 The following subsections are currently supported within the [plugins] section:
750 The \fBpwqual\fP subsection controls modules for the password quality interface, which is used to reject weak passwords when passwords are changed. In addition to any registered dynamic modules, the following built\-in modules exist (and may be disabled with the disable tag):
755 Checks against the realm dictionary file
759 Rejects empty passwords
763 Checks against user information stored in Hesiod (only if Kerberos was built with Hesiod support)
767 Checks against components of the principal name
769 .SS kadm5_hook interface
771 The \fBkadm5_hook\fP interface provides plugins with information on principal creation, modification, password changes and deletion. This interface can be used to write a plugin to synchronize MIT Kerberos with another database such as Active Directory. No plugins are built in for this interface.
772 .SS clpreauth and kdcpreauth interfaces
774 The \fBclpreauth\fP and \fBkdcpreauth\fP interfaces allow plugin modules to provide client and KDC preauthentication mechanisms. The following built\-in modules exist for these interfaces:
779 This module implements the PKINIT preauthentication mechanism.
781 .B \fBencrypted_challenge\fP
783 This module implements the encrypted challenge FAST factor.
785 .B \fBencrypted_timestamp\fP
787 This module implements the encrypted timestamp mechanism.
795 pkinit identity syntax
798 pkinit krb5.conf options
804 The following are pkinit\-specific options. Note that these values may be specified in \fI[libdefaults]\fP as global defaults, or within a realm\-specific subsection of \fI[libdefaults]\fP, or may be specified as realm\-specific values in the \fI[realms]\fP section. Also note that a realm\-specific value over\-rides, does not add to, a generic \fI[libdefaults]\fP specification. The search order is:
808 realm\-specific subsection of [libdefaults]
818 pkinit_anchors = FILE:/usr/local/example.com.crt
827 realm\-specific value in the [realms] section,
835 .B OTHERREALM.ORG = {
837 pkinit_anchors = FILE:/usr/local/otherrealm.org.crt
846 generic value in the [libdefaults] section.
853 pkinit_anchors = DIR:/usr/local/generic_trusted_cas/
859 .SS Specifying pkinit identity information
861 The syntax for specifying Public Key identity, trust, and revocation information for pkinit is as follows:
864 .B FILE:file\-name[,key\-file\-name]
866 This option has context\-specific behavior.
875 \fIfile\-name\fP specifies the name of a PEM\-format file containing the user\(aqs certificate. If \fIkey\-file\-name\fP is not specified, the user\(aqs private key is expected to be in file\-name as well. Otherwise, \fIkey\-file\-name\fP is the name of the file containing the private key.
886 \fIfile\-name\fP is assumed to be the name of an OpenSSL\-style ca\-bundle file.
890 .B DIR:directory\-name
892 This option has context\-specific behavior.
901 \fIdirectory\-name\fP specifies a directory with files named *.crt and *.key, where the first part of the file name is the same for matching pairs of certificate and private key files. When a file with a name ending with .crt is found, a matching file ending with .key is assumed to contain the private key. If no such file is found, then the certificate in the .crt is not used.
912 \fIdirectory\-name\fP is assumed to be an OpenSSL\-style hashed CA directory where each CA cert is stored in a file named \fIhash\-of\-ca\-cert.#\fP. This infrastructure is encouraged, but all files in the directory will be examined and if they contain certificates (in PEM format), they will be used.
919 \fIdirectory\-name\fP is assumed to be an OpenSSL\-style hashed CA directory where each revocation list is stored in a file named \fIhash\-of\-ca\-cert.r#\fP. This infrastructure is encouraged, but all files in the directory will be examined and if they contain a revocation list (in PEM format), they will be used.
922 .B PKCS12:pkcs12\-file\-name
924 \fIpkcs12\-file\-name\fP is the name of a PKCS #12 format file, containing the user\(aqs certificate and private key.
926 .B PKCS11:[module_name=]module\-name[:slotid=slot\-id][:token=token\-label][:certid=cert\-id][:certlabel=cert\-label]
928 All keyword/values are optional. module\-name specifies the location of a library implementing PKCS #11. If a value is encountered with no keyword, it is assumed to be the \fImodule\-name\fP. If no module\-name is specified, the default is \fIopensc\-pkcs11.so\fP. \fIslotid=\fP and/or \fItoken=\fP may be specified to force the use of a particular smard card reader or token if there is more than one available. \fIcertid=\fP and/or \fIcertlabel=\fP may be specified to force the selection of a particular certificate on the device. See the \fIpkinit_cert_match\fP configuration option for more ways to select a particular certificate to use for pkinit.
930 .B ENV:environment\-variable\-name
932 environment\-variable\-name specifies the name of an environment variable which has been set to a value conforming to one of the previous values. For example, \fIENV:X509_PROXY\fP, where environment variable \fIX509_PROXY\fP has been set to \fIFILE:/tmp/my_proxy.pem\fP.
934 .SS PKINIT krb5.conf options
937 .B \fBpkinit_anchors\fP
939 Specifies the location of trusted anchor (root) certificates which the client trusts to sign KDC certificates. This option may be specified multiple times. These values from the config file are not used if the user specifies X509_anchors on the command line.
941 .B \fBpkinit_cert_match\fP
943 Specifies matching rules that the client certificate must match before it is used to attempt pkinit authentication. If a user has multiple certificates available (on a smart card, or via other media), there must be exactly one certificate chosen before attempting pkinit authentication. This option may be specified multiple times. All the available certificates are checked against each rule in order until there is a match of exactly one certificate.
945 The Subject and Issuer comparison strings are the \fI\%RFC 2253\fP string representations from the certificate Subject DN and Issuer DN values.
947 The syntax of the matching rules is:
951 [relation\-operator]component\-rule ...
958 .B \fIrelation\-operator\fP
960 can be either \fB&&\fP, meaning all component rules must match, or \fB||\fP, meaning only one component rule must match. The default is &&.
962 .B \fIcomponent\-rule\fP
964 can be one of the following. Note that there is no punctuation or whitespace between component rules.
966 \fI<SUBJECT>regular\-expression\fP
968 \fI<ISSUER>regular\-expression\fP
970 \fI<SAN>regular\-expression\fP
973 .B \fI<EKU>extended\-key\-usage\-list\fP
975 where \fIextended\-key\-usage\-list\fP is a comma\-separated list of required Extended Key Usage values. All values in the list must be present in the certificate.
995 .B \fI<KU>key\-usage\-list\fP
997 where \fIkey\-usage\-list\fP is a comma\-separated list of required Key Usage values. All values in the list must be present in the certificate.
1017 pkinit_cert_match = ||<SUBJECT>.*DoE.*<SAN>.*@EXAMPLE.COM
1018 pkinit_cert_match = &&<EKU>msScLogin,clientAuth<ISSUER>.*DoE.*
1019 pkinit_cert_match = <EKU>msScLogin,clientAuth<KU>digitalSignature
1023 .B \fBpkinit_eku_checking\fP
1025 This option specifies what Extended Key Usage value the KDC certificate presented to the client must contain. (Note that if the KDC certificate has the pkinit SubjectAlternativeName encoded as the Kerberos TGS name, EKU checking is not necessary since the issuing CA has certified this as a KDC certificate.) The values recognized in the krb5.conf file are:
1030 This is the default value and specifies that the KDC must have the id\-pkinit\-KPKdc EKU as defined in \fI\%RFC 4556\fP.
1032 .B \fIkpServerAuth\fP
1034 If kpServerAuth is specified, a KDC certificate with the id\-kp\-serverAuth EKU as used by Microsoft will be accepted.
1038 If none is specified, then the KDC certificate will not be checked to verify it has an acceptable EKU. The use of this option is not recommended.
1041 .B \fBpkinit_dh_min_bits\fP
1043 Specifies the size of the Diffie\-Hellman key the client will attempt to use. The acceptable values are currently 1024, 2048, and 4096. The default is 2048.
1045 .B \fBpkinit_identities\fP
1047 Specifies the location(s) to be used to find the user\(aqs X.509 identity information. This option may be specified multiple times. Each value is attempted in order until identity information is found and authentication is attempted. Note that these values are not used if the user specifies X509_user_identity on the command line.
1049 .B \fBpkinit_kdc_hostname\fP
1051 The presense of this option indicates that the client is willing to accept a KDC certificate with a dNSName SAN (Subject Alternative Name) rather than requiring the id\-pkinit\-san as defined in \fI\%RFC 4556\fP. This option may be specified multiple times. Its value should contain the acceptable hostname for the KDC (as contained in its certificate).
1053 .B \fBpkinit_longhorn\fP
1055 If this flag is set to true, we are talking to the Longhorn KDC.
1057 .B \fBpkinit_pool\fP
1059 Specifies the location of intermediate certificates which may be used by the client to complete the trust chain between a KDC certificate and a trusted anchor. This option may be specified multiple times.
1061 .B \fBpkinit_require_crl_checking\fP
1063 The default certificate verification process will always check the available revocation information to see if a certificate has been revoked. If a match is found for the certificate in a CRL, verification fails. If the certificate being verified is not listed in a CRL, or there is no CRL present for its issuing CA, and \fIpkinit_require_crl_checking\fP is false, then verification succeeds.
1065 However, if \fIpkinit_require_crl_checking\fP is true and there is no CRL information available for the issuing CA, then verification fails.
1067 \fIpkinit_require_crl_checking\fP should be set to true if the policy is such that up\-to\-date CRLs must be present for every CA.
1069 .B \fBpkinit_revoke\fP
1071 Specifies the location of Certificate Revocation List (CRL) information to be used by the client when verifying the validity of the KDC certificate presented. This option may be specified multiple times.
1073 .B \fBpkinit_win2k\fP
1075 This flag specifies whether the target realm is assumed to support only the old, pre\-RFC version of the protocol. The default is false.
1077 .B \fBpkinit_win2k_require_binding\fP
1079 If this flag is set to true, it expects that the target KDC is patched to return a reply with a checksum rather than a nonce. The default is false.
1081 .SH SAMPLE KRB5.CONF FILE
1083 Here is an example of a generic krb5.conf file:
1088 default_realm = ATHENA.MIT.EDU
1089 default_tkt_enctypes = des3\-hmac\-sha1 des\-cbc\-crc
1090 default_tgs_enctypes = des3\-hmac\-sha1 des\-cbc\-crc
1091 dns_lookup_kdc = true
1092 dns_lookup_realm = false
1096 kdc = kerberos.mit.edu
1097 kdc = kerberos\-1.mit.edu
1098 kdc = kerberos\-2.mit.edu:750
1099 admin_server = kerberos.mit.edu
1100 master_kdc = kerberos.mit.edu
1101 default_domain = mit.edu
1104 kdc = kerberos.example.com
1105 kdc = kerberos\-1.example.com
1106 admin_server = kerberos.example.com
1108 OPENLDAP.MIT.EDU = {
1109 kdc = kerberos.mit.edu
1110 admin_server = kerberos.mit.edu
1111 database_module = openldap_ldapconf
1115 .mit.edu = ATHENA.MIT.EDU
1116 mit.edu = ATHENA.MIT.EDU
1128 admin_server = FILE=/var/kadm5.log
1130 ldap_kerberos_container_dn = cn=krbcontainer,dc=example,dc=com
1132 openldap_ldapconf = {
1134 disable_last_success = true
1135 ldap_kerberos_container_dn = cn=krbcontainer,dc=example,dc=com
1136 ldap_kdc_dn = "cn=krbadmin,dc=example,dc=com"
1137 # this object needs to have read rights on
1138 # the realm container and principal subtrees
1139 ldap_kadmind_dn = "cn=krbadmin,dc=example,dc=com"
1140 # this object needs to have read and write rights on
1141 # the realm container and principal subtrees
1142 ldap_service_password_file = /etc/kerberos/service.keyfile
1143 ldap_servers = ldaps://kerberos.mit.edu
1144 ldap_conns_per_server = 5
1158 .\" Generated by docutils manpage writer.
projects / krb5.git / blob