krb5.conf(4) (man pages section 4: File Formats)

man pages section 4: File Formats

krb5.conf(4)

Name

krb5.conf– Kerberos configuration file

Synopsis

/etc/krb5/krb5.conf

Description

The krb5.conf file contains Kerberos configuration information, including the locations of KDCs and administration daemons for the Kerberos realms of interest, defaults for the current realm and for Kerberos applications, and mappings of host names onto Kerberos realms. This file must reside on all Kerberos clients.

The format of the krb5.conf consists of sections headings in square brackets. Each section can contain zero or more configuration variables (called relations), of the form:

relation= relation-value

relation-subsection = {

relation= relation-value

}

The krb5.conf file can contain any or all of the following sections:

libdefaults: Contains default values used by the Kerberos V5 library.
appdefaults: Contains subsections for Kerberos V5 applications, where relation-subsection is the name of an application. Each subsection describes application-specific defaults.
realms: Contains subsections for Kerberos realms, where relation-subsection is the name of a realm. Each subsection contains relations that define the properties for that particular realm.
domain_realm: 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.
logging: Contains relations which determine how Kerberos programs are to perform logging.
capaths: 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 can be used in cross-realm authentication. It is also used by the end-service when checking the transited field for trusted intermediate realms.
dbmodules: Contains relations for Kerberos database plug-in-specific configuration information.
kdc: For a Key Distribution Center (KDC), can contain the location of the kdc.conf file.

The `[libdefaults]` Section

The [libdefaults] section can contain any of the following relations:

database_module

Selects the dbmodule section entry to use to access the Kerberos database. If this parameter is not present the code uses the standard db2–based Kerberos database.

default_keytab_name

Specifies the default keytab name to be used by application servers such as telnetd and rlogind. The default is /etc/krb5/krb5.keytab.

default_realm

Identifies the default Kerberos realm for the client. Set its value to your Kerberos realm.

default_tgs_enctypes

Identifies the supported list of session key encryption types that should be returned by the KDC. The list can be delimited with commas or whitespace. The supported encryption types are des3-cbc-sha1-kd, des-cbc-crc, des-cbc-md5, arcfour-hmac-md5, arcfour-hmac-md5-exp, aes128-cts-hmac-sha1-96, and aes256-cts-hmac-sha1-96.

default_tkt_enctypes

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 supported encryption types are des3-cbc-sha1-kd, des-cbc-crc, des-cbc-md5, arcfour-hmac-md5, arcfour-hmac-md5-exp, aes128-cts-hmac-sha1-96, and aes256-cts-hmac-sha1-96.

clockskew

Sets the maximum allowable amount of clock skew in seconds that the library tolerates before assuming that a Kerberos message is invalid. The default value is 300 seconds, or five minutes.

forwardable = [true | false]

Sets the “forwardable” flag in all tickets. This allows users to transfer their credentials from one host to another without reauthenticating. This option can also be set in the [appdefaults] or [realms] section (see below) to limit its use in particular applications or just to a specific realm.

permitted_enctypes

This relation controls the encryption types for session keys permitted by server applications that use Kerberos for authentication. In addition, it controls the encryption types of keys added to a keytab by means of the kadmin(1M) ktadd command. The default is: aes256-cts-hmac-sha1-96, aes128-cts-hmac-sha1-96, des3-hmac-sha1-kd, arcfour-hmac-md5, arcfour-hmac-md5-exp, des-cbc-md5, des-cbc-crc.

proxiable = [true | false]

Sets the proxiable flag in all tickets. This allows users to create a proxy ticket that can be transferred to a kerberized service to allow that service to perform some function on behalf of the original user. This option can also be set in the [appdefaults] or [realms] section (see below) to limit its use in particular applications or just to a specific realm.

renew_lifetime =lifetime

Requests renewable tickets, with a total lifetime of lifetime. The value for lifetime must be followed immediately by one of the following delimiters:

s: seconds
m: minutes
h: hours
d: days

Example:

renew_lifetime = 90m

Do not mix units. A value of “3h30m” results in an error.

max_lifetime =lifetime

Sets the requested maximum lifetime of the ticket. The values for lifetime follow the format described for the renew_lifetime option, above.

dns_lookup_kdc

Indicates whether DNS SRV records need to be used to locate the KDCs and the other servers for a realm, if they have not already been listed in the [realms] section. This option makes the machine vulnerable to a certain type of DoS attack if somone spoofs the DNS records and does a redirect to another server. This is, however, no worse than a DoS, since the bogus KDC is unable to decode anything sent (excepting the initial ticket request, which has no encrypted data). Also, anything the fake KDC sends out isl not trusted without verification (the local machine is unaware of the secret key to be used). If dns_lookup_kdc is not specified but dns_fallback is, then that value is used instead. In either case, values (if present) in the [realms] section override DNS. dns_lookup_kdc is enabled by default.

dns_lookup_realm

Indicates whether DNS TXT records need to be used to determine the Kerberos realm information and/or the host/domain name-to-realm mapping of a host, if this information is not already present in the krb5.conf file. Enabling this option might make the host vulnerable to a redirection attack, wherein spoofed DNS replies persuade a client to authenticate to the wrong realm. In a realm with no cross-realm trusts, this a DoS attack. If dns_lookup_realm is not specified but dns_fallback is, then that value is used instead. In either case, values (if present) in the [libdefaults] and [domain_realm] sections override DNS.

dns_fallback

Generic flag controlling the use of DNS for retrieval of information about Kerberos servers and host/domain name-to-realm mapping. If both dns_lookup_kdc and dns_lookup_realm have been specified, this option has no effect.

verify_ap_req_nofail [true | false]

If true, the local keytab file (/etc/krb5/krb5.keytab) must contain an entry for the local host principal, for example, host/foo.bar.com@FOO.COM. This entry is needed to verify that the TGT requested was issued by the same KDC that issued the key for the host principal. If undefined, the behavior is as if this option were set to true. Setting this value to false leaves the system vulnerable to DNS spoofing attacks. This parameter can be in the [realms] section to set it on a per-realm basis, or it can be in the [libdefaults] section to make it a network-wide setting for all realms.

The `[appdefaults]` Section

This section contains subsections for Kerberos V5 applications, where relation-subsection is the name of an application. Each subsection contains relations that define the default behaviors for that application.

The following relations can be found in the [appdefaults] section, though not all relations are recognized by all kerberized applications. Some are specific to particular applications.

autologin = [true | false]: Forces the application to attempt automatic login by presenting Kerberos credentials. This is valid for the following applications: rlogin, rsh, rcp, rdist, and telnet.
encrypt = [true | false]: Forces applications to use encryption by default (after authentication) to protect the privacy of the sessions. This is valid for the following applications: rlogin, rsh, rcp, rdist, and telnet.
forward = [true | false]: Forces applications to forward the user'ss credentials (after authentication) to the remote server. This is valid for the following applications: rlogin, rsh, rcp, rdist, and telnet.
forwardable = [true | false]: See the description in the [libdefaults] section above. This is used by any application that creates a ticket granting ticket and also by applications that can forward tickets to a remote server.
proxiable = [true | false]: See the description in the [libdefaults] section above. This is used by any application that creates a ticket granting ticket.
renewable = [true | false]: Creates a TGT that can be renewed (prior to the ticket expiration time). This is used by any application that creates a ticket granting ticket.
no_addresses = [true | false]: Creates tickets with no address bindings. This is to allow tickets to be used across a NAT boundary or when using multi-homed systems. This option is valid in the kinit [appdefault] section only.
max_life =lifetime: Sets the maximum lifetime of the ticket, with a total lifetime of lifetime. The values for lifetime follow the format described in the [libdefaults] section above. This option is obsolete and is removed in a future release of the Solaris operating system.
max_renewable_life =lifetime: Requests renewable tickets, with a total lifetime of lifetime. The values for lifetime follow the format described in the [libdefaults] section above. This option is obsolete and is removed in a future release of the Solaris operating system.
rcmd_protocol = [ rcmdv1 | rcmdv2 ]: Specifies which Kerberized “rcmd” protocol to use when using the Kerberized rlogin(1), rsh(1), rcp(1), or rdist(1) programs. The default is to use rcmdv2 by default, as this is the more secure and more recent update of the protocol. However, when talking to older MIT or SEAM-based “rcmd” servers, it can be necessary to force the new clients to use the older rcmdv1 protocol. This option is valid only for the following applications: rlogin, rcp, rsh, and rdist.

gkadmin = {
      help_url = \
http://docs.sun.com/app/docs/doc/816-4557/6maosrjmr?q=gkadmin&a=view
}

The preceding URL is subject to change. On the docs.sun.com web site, view the chapter on the Solaris Kerberos implementation in the System Administration Guide: Security Services.

The following application defaults can be set to true or false:

kinit
   forwardable = true
   proxiable = true
   renewable = true
   no_addresses = true
   max_life = delta_time
   max_renewable_life = delta_time

See kinit(1) for the valid time duration formats you can specify for delta_time.

In the following example, kinit gets forwardable tickets by default and telnet has three default behaviors specified:

[appdefaults]
   kinit = {
      forwardable = true
   }

   telnet = {
      forward = true
      encrypt = true
      autologin = true
   }

The application defaults specified here are overridden by those specified in the [realms] section.

The `[realms]` Section

This section contains subsections for Kerberos realms, where relation-subsection is the name of a realm. Each subsection contains relations that define the properties for that particular realm. The following relations can be specified in each [realms] subsection:

admin_server

Identifies the host where the Kerberos administration daemon (kadmind) is running. Typically, this is the master KDC.

application defaults

Application defaults that are specific to a particular realm can be specified within a [realms] subsection. Realm-specific application defaults override the global defaults specified in the [appdefaults] section.

auth_to_local_realm

For use in the default realm, non-default realms can be equated with the default realm for authenticated name-to-local name mapping.

auth_to_local_names

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.

auth_to_local

This tag allows you to set a general rule for mapping principal names to local user names. It is used if there is not an explicit mapping for the principal name that is being translated. The possible values are:

RULE:[<ncomps>:<format>](<regex>)s/<regex>/<text>/

Each rule has three parts:

First part—Formulate the string on which to perform operations:

If not present then the string defaults to the fully flattened principal minus the realm name. Otherwise the syntax is as follows:

"[" <ncomps> ":" <format> "]"

Where:

<ncomps> is the number of expected components for this rule. If the particular principal does not have this number of components, then this rule does not apply.

<format> is a string of <component> or verbatim characters to be inserted.

<component> is of the form “$”<number> to select the <number>th component. <number> begins from 1.

Second part—select rule validity:

If not present, this rule can apply to all selections. Otherwise the syntax is as follows:

"(" <regex> ")"

Where:

<regex> is a selector regular expression. If this regular expression matches the whole pattern generated from the first part, then this rule still applies.

Third part—Transform rule:

If not present, then the selection string is passed verbatim and is matched. Otherwise, the syntax is as follows:

<rule> ...

Where:

<rule> is of the form:

"s/" <regex> "/" <text> "/" ["g"]

Regular expressions are defined in regex(5).

For example:

auth_to_local = RULE:[1:$1@$0](.*@.*ACME\.COM)s/@.*//

The preceding maps username@ACME.COM and all sub-realms of ACME.COM to username.

DEFAULT

The principal name is used as the local name. If the principal has more than one component or is not in the default realm, this rule is not applicable and the conversion fails.

database_module

Selects the dbmodule section entry to use to access the Kerberos database.

extra_addresses...

This allows a computer to use multiple local addresses, to allow Kerberos to work in a network that uses NATs. The addresses should be in a comma-separated list.

kdc

The name of a host running a KDC for that realm. An optional port number (separated from the hostname by a colon) can be included.

kpasswd_server

Identifies the host where the Kerberos password-changing server is running. Typically, this is the same as host indicated in the admin_server. If this parameter is omitted, the host in admin_server is used. You can also specify a port number if the server indicated by kpasswd_server runs on a port other than 464 (the default). The format of this parameter is: hostname[:port].

kpasswd_protocol

Identifies the protocol to be used when communicating with the server indicated by kpasswd_server. By default, this parameter is defined to be RPCSEC_GSS, which is the protocol used by Solaris-based administration servers. To be able to change a principal's password stored on non-Solaris Kerberos server, such as Microsoft Active Directory or MIT Kerberos, this value should be SET_CHANGE. This indicates that a non-RPC– based protocol is used to communicate the password change request to the server in the kpasswd_server entry.

udp_preference_limit

When sending a message to the KDC, the library tries using TCP before UDP if the size of the message is above udp_preference_limit. If the message is smaller than udp_preference_limit, then UDP is tried before TCP. Regardless of the size, both protocols are tried if the first attempt fails.

verify_ap_req_nofail [true | false]

If true, the local keytab file (/etc/krb5/krb5.keytab) must contain an entry for the local host principal, for example, host/foo.bar.com@FOO.COM. This entry is needed to verify that the TGT requested was issued by the same KDC that issued the key for the host principal. If undefined, the behavior is as if this option were set to true. Setting this value to false leaves the system vulnerable to DNS spoofing attacks. This parameter might be in the [realms] section to set it on a per-realm basis, or it might be in the [libdefaults] section to make it a network-wide setting for all realms.

The parameters “forwardable”, “proxiable”, and “renew_lifetime” as described in the [libdefaults] section (see above) are also valid in the [realms] section.

Notice that kpasswd_server and kpasswd_protocol are realm-specific parameters. Most often, you need to specify them only when using a non-Solaris-based Kerberos server. Otherwise, the change request is sent over RPCSEC_GSS to the Solaris Kerberos administration server.

The `[domain_realm]` Section

This section provides a translation from a domain name or hostname to a Kerberos realm name. The relation can be a host name, or a domain name, where domain names are indicated by a period (`.') prefix. relation-value is the Kerberos realm name for that particular host or domain. Host names and domain names should be in lower case.

If no translation entry applies, the host's realm is considered to be the hostname's domain portion converted to upper case. For example, the following [domain_realm] section maps crash.mit.edu into the TEST.ATHENA.MIT.EDU realm:

[domain_realm]
   .mit.edu = ATHENA.MIT.EDU
   mit.edu = ATHENA.MIT.EDU
   crash.mit.edu = TEST.ATHENA.MIT.EDU
   .fubar.org = FUBAR.ORG
   fubar.org = FUBAR.ORG

All other hosts in the mit.edu domain maps by default to the ATHENA.MIT.EDU realm, and all hosts in the fubar.org domain maps by default into the FUBAR.ORG realm. The entries for the hosts mit.edu and fubar.org. Without these entries, these hosts would be mapped into the Kerberos realms EDU and ORG, respectively.

The `[logging]` Section

This section indicates how Kerberos programs are to perform logging. There are two types of relations for this section: relations to specify how to log and a relation to specify how to rotate kdc log files.

The following relations can be defined to specify how to log. The same relation can be repeated if you want to assign it multiple logging methods.

admin_server: Specifies how to log the Kerberos administration daemon (kadmind). The default is FILE:/var/krb5/kadmin.log.
default: Specifies how to perform logging in the absence of explicit specifications otherwise.
kdc: Specifies how the KDC is to perform its logging. The default is FILE:/var/krb5/kdc.log.

The admin_server, default, and kdc relations can have the following values:

FILE:filename FILE=filename: This value causes the entity's 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.
STDERR: This value causes the entity's logging messages to go to its standard error stream.
CONSOLE: This value causes the entity's logging messages to go to the console, if the system supports it.
DEVICE=devicename: This causes the entity's logging messages to go to the specified device.
SYSLOG[:severity[:facility]]: This causes the entity's logging messages to go to the system log.

The severity argument specifies the default severity of system log messages. This can be any of the following severities supported by the syslog(3C) 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.

The facility argument specifies the facility under which the messages are logged. This can be any of the following facilities supported by the syslog(3C) 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.

If no severity is specified, the default is ERR. If no facility is specified, the default is AUTH.

The following relation can be defined to specify how to rotate kdc log files if the FILE: value is being used to log:

kdc_rotate: A relation subsection that enables kdc logging to be rotated to multiple files based on a time interval. This can be used to avoid logging to one file, which might grow too large and bring the KDC to a halt.

The time interval for the rotation is specified by the period relation. The number of log files to be rotated is specified by the versions relation. Both the period and versions (described below) should be included in this subsection. And, this subsection applies only if the kdc relation has a FILE: value.

The following relations can be specified for the kdc_rotate relation subsection:

period=delta_time: Specifies the time interval before a new log file is created. See the TimeFormats section in kinit(1) for the valid time duration formats you can specify for delta_time. If period is not specified or set to never, no rotation occurs.

Specifying a time interval does not mean that the log files are rotated at the time interval based on real time. This is because the time interval is checked at each attempt to write a record to the log, or when logging is actually occurring. Therefore, rotation occurs only when logging has actually occurred for the specified time interval.

versions=number: Specifies how many previous versions are saved before the rotation begins. A number is appended to the log file, starting with 0 and ending with (number - 1). For example, if versions is set to 2, up to three logging files are created (filename, filename.0, and filename.1) before the first one is overwritten to begin the rotation.

Notice that if versions is not specified or set to 0, only one log file is created, but it is overwritten whenever the time interval is met.

In the following example, the logging messages from the Kerberos administration daemon goes to the console. The logging messages from the KDC is appended to the /var/krb5/kdc.log, which is rotated between twenty-one log files with a specified time interval of a day.

[logging]
   admin_server = CONSOLE
   kdc = FILE:/export/logging/kadmin.log
   kdc_rotate = {
      period = 1d
      versions = 20
   }

The `[capaths]` Section

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.

A client uses this section to find the authentication path between its realm and the realm of the server. The server uses this section to verify the authentication path used by the client, by checking the transited field of the received ticket.

There is a subsection for each participating realm, and each subsection has relations named for each of the realms. The relation-value is an intermediate realm which can participate in the cross-realm authentication. The relations can be repeated if there is more than one intermediate realm. A value of '.' means that the two realms share keys directly, and no intermediate realms should be allowed to participate.

There are n**2 possible entries in this table, but only those entries which is needed on the client or the server need to be present. The client needs a subsection named for its local realm, with relations named for all the realms of servers it needs to authenticate with. A server needs a subsection named for each realm of the clients it serves.

For example, ANL.GOV, PNL.GOV, and NERSC.GOV all wish to use the ES.NET realm as an intermediate realm. ANL has a sub realm of TEST.ANL.GOV, which authenticates with NERSC.GOV but not PNL.GOV. The [capath] section for ANL.GOV systems would look like this:

[capaths]
   ANL.GOV = { 
       TEST.ANL.GOV = .
       PNL.GOV = ES.NET
       NERSC.GOV = ES.NET
       ES.NET = .
   }

   TEST.ANL.GOV = { 
       ANL.GOV = .
   }

   PNL.GOV = { 
       ANL.GOV = ES.NET
   }

   NERSC.GOV = { 
      ANL.GOV = ES.NET
   }

   ES.NET = { 
      ANL.GOV = .
   }

The [capath] section of the configuration file used on NERSC.GOV systems would look like this:

[capaths]
   NERSC.GOV = {
      ANL.GOV = ES.NET
      TEST.ANL.GOV = ES.NET
      TEST.ANL.GOV = ANL.GOV
      PNL.GOV = ES.NET
      ES.NET = .
   }

   ANL.GOV = { 
      NERSC.GOV = ES.NET
   }

   PNL.GOV = { 
      NERSC.GOV = ES.NET
   }

   ES.NET = { 
      NERSC.GOV = .
   }

   TEST.ANL.GOV = { 
      NERSC.GOV = ANL.GOV
      NERSC.GOV = ES.NET
   }

In the above examples, the ordering is not important, except when the same relation is used more than once. The client uses this to determine the path. (It is not important to the server, since the transited field is not sorted.)

PKINIT-specific Options

The following are pkinit-specific options. These values can be specified in [libdefaults] as global defaults, or within a realm-specific subsection of [libdefaults], or can be specified as realm-specific values in the [realms] section. A realm-specific value overrides, does not add to, a generic [libdefaults] specification.

The search order is:

realm-specific subsection of [libdefaults]

          [libdefaults]
              EXAMPLE.COM = {
                  pkinit_anchors = FILE:/usr/local/example.com.crt

realm-specific value in the [realms] section

          [realms]
              OTHERREALM.ORG = {
                  pkinit_anchors = FILE:/usr/local/otherrealm.org.crt

generic value in the [libdefaults] section

          [libdefaults]
              pkinit_anchors = DIR:/usr/local/generic_trusted_cas/

The syntax for specifying Public Key identity, trust, and revocation information for pkinit is as follows:

pkinit_identities = URI

Specifies the location(s) to be used to find the user's X.509 identity information. This option can be specified multiple times. Each value is attempted in order until identity information is found and authentication is attempted. These values are not used if the user specifies X509_user_identity on the command line.

Valid URI types are FILE, DIR, PKCS11, PKCS12, and ENV. See the PKINIT URI Types section for more details.

pkinit_anchors = URI

Specifies the location of trusted anchor (root) certificates which the client trusts to sign KDC certificates. This option can be specified multiple times. These values from the config file are not used if the user specifies X509_anchors on the command line.

Valid URI types are FILE and DIR. See the PKINIT URI Types section for more details.

pkinit_pool = URI

Specifies the location of intermediate certificates which can be used by the client to complete the trust chain between a KDC certificate and a trusted anchor. This option can be specified multiple times.

Valid URI types are FILE and DIR. See the PKINIT URI Types section for more details.

pkinit_revoke = URI

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 can be specified multiple times.

The only valid URI type is DIR. See the PKINIT URI Types section for more details.

pkinit_require_crl_checking = value

The default certificate verification process always checks 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 pkinit_require_crl_checking is false, then verification succeeds. However, if pkinit_require_crl_checking is true and there is no CRL information available for the issuing CA, then verification fails. pkinit_require_crl_checking should be set to true if the policy is such that up-to-date CRLs must be present for every CA.

pkinit_dh_min_bits = value

Specifies the size of the Diffie-Hellman key the client attempts to use. The acceptable values are currently 1024, 2048, and 4096. The default is 2048.

pkinit_win2k = value

This flag specifies whether the target realm is assumed to support only the old, pre-RFC version of the protocol. The default is false.

pkinit_win2k_require_binding = value

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.

pkinit_eku_checking = value

This option specifies what Extended Key Usage value the KDC certificate presented to the client must contain. 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:

kpKDC: This is the default value and specifies that the KDC must have the id-pkinit-KPKdc EKU as defined in RFC4556.
kpServerAuth: If kpServerAuth is specified, a KDC certificate with the id-kp-serverAuth EKU as used by Microsoft is accepted.
none: If none is specified, then the KDC certificate is not checked to verify it has an acceptable EKU. The use of this option is not recommended.

pkinit_kdc_hostname = value

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 RFC4556. This option can be specified multiple times. Its value should contain the acceptable hostname for the KDC (as contained in its certificate).

pkinit_cert_match = rule

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 by way of another media), there must be exactly one certificate chosen before attempting pkinit authentication. This option can be specified multiple times. All the available certificates are checked against each rule in order until there is a match of exactly one certificate.

The Subject and Issuer comparison strings are the RFC2253 string representations from the certificate Subject DN and Issuer DN values.

The syntax of the matching rules is:

[relation-operator]component-rule `...'

where

relation-operator

Specify relation-operator as &&, meaning all component rules must match, or ||, meaning only one component rule must match. If relation-operator is not specified, the default is &&.

component-rule

There is no punctuation or white space between component rules.Specify component-rule as one of the following:

`<SUBJECT>'regular-expression

`<ISSUER>'regular-expression

`<SAN>'regular-expression

`<EKU>'extended-key-usage-list
               where extended-key-usage-list is a comma-separated list
               of required Extended Key Usage values.  All values in
               the list must be present in the certificate.
                    `pkinit'
                    `msScLogin'
                    `clientAuth'
                    `emailProtection'
`<KU>'key-usage-list
               where key-usage-list is a comma-separated list of
               required Key Usage values.  All values in the list must
               be present in the certificate.
                    `digitalSignature'

Examples:

pkinit_cert_match = ||<SUBJECT>.*DoE.*<SAN>.*@EXAMPLE.COM
pkinit_cert_match = &&<EKU>msScLogin,clientAuth<ISSUER>.*DoE.*
pkinit_cert_match = <EKU>msScLogin,clientAuth<KU>digitalSignature

PKINIT URI Types

FILE:file-name[,key-file-name]

This option has context-specific behavior.

pkinit_identities: file-name specifies the name of a PEM-format file containing the user's certificate. If key-file-name is not specified, the user's private key is expected to be in file-name as well. Otherwise, key-file-name is the name of the file containing the private key.
pkinit_anchors pkinit_pool: file-name is assumed to be the name of an OpenSSL-style ca-bundle file. The ca-bundle file should be base-64 encoded.

DIR:directory-name

This option has context-specific behavior.

pkinit_identities: directory-name 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.
pkintit_anchors pkinit_pool: directory-name is assumed to be an OpenSSL-style hashed CA directory where each CA cert is stored in a file named hash-of-ca-cert.#. This infrastructure is encouraged, but all files in the directory is examined and if they contain certificates (in PEM format), they are used.

PKCS12:pkcs12-file-name

pkcs12-file-name is the name of a PKCS #12 format file, containing the user's certificate and private key.

PKCS11:[slotid=slot-id][:token=token-label][:certid=cert-id][:certlabel=cert-label]

All keyword/values are optional. PKCS11 modules (for example, opensc-pkcs11.so) must be installed as a crypto provider under libpkcs11(3LIB). slotid= and/or token= can be specified to force the use of a particular smart card reader or token if there is more than one available. certid= and/or certlabel= can be specified to force the selection of a particular certificate on the device. See the pkinit_cert_match configuration option for more ways to select a particular certificate to use for pkinit.

ENV:environment-variable-name

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, ENV:X509_PROXY, where environment variable X509_PROXY has been set to FILE:/tmp/my_proxy.pem.

The `[dbmodules]` Section

This section consists of relations that provide configuration information for plug-in modules. In particular, the relations describe the configuration for LDAP KDB plug-in. Use of the db2 KDB plug-in is the default behavior and that this section does not need to be filled out in that case.

db_library

Name of the plug-in library. To use the LDAP KDB plug-in the name must be kdb_ldap. The default value is db2.

db_module_dir

Path to the plug-in libraries. The default is /usr/lib/krb5.

ldap_cert_path

Path to the Network Security Services (NSS) trusted database for an SSL connection. This is a required parameter when using the LDAP KDB plug-in.

ldap_conns_per_server

Number of connections per LDAP instance. The default is 5.

ldap_kadmind_dn

Bind DN for kadmind. This specifies the DN that the kadmind service uses when binding to the LDAP Directory Server. The password for this bind DN should be in the ldap_service_password_file.

ldap_kdc_dn

Bind DN for a Key Distribution Center (KDC). This specifies the DN that the krb5kdc service use when binding to the LDAP Directory Server. The password for this bind DN should be in the ldap_service_password_file.

ldap_servers

List of LDAP directory servers in URI format. Use of either of the following is acceptable.

ldap://<ds hostname>:<SSL port>
ldap://<ds hostname>

Each server URI should be separated by whitespace.

ldap_service_password_file

File containing stashed passwords used by the KDC when binding to the LDAP Directory Server. The default is /var/krb5/service_passwd. This file is created using kdb5_ldap_util(1M).

ldap_ssl_port

Port number for SSL connection with directory server. The default is 389.

Examples

Example 1 Sample File

The following is an example of a generic krb5.conf file:

[libdefaults]
   default_realm = ATHENA.MIT.EDU
   default_tkt_enctypes = des-cbc-crc
   default_tgs_enctypes = des-cbc-crc

[realms]
   ATHENA.MIT.EDU = { 
      kdc = kerberos.mit.edu
      kdc = kerberos-1.mit.edu
      kdc = kerberos-2.mit.edu
      admin_server = kerberos.mit.edu
      auth_to_local_realm = KRBDEV.ATHENA.MIT.EDU
   }

   FUBAR.ORG = { 
      kdc = kerberos.fubar.org
      kdc = kerberos-1.fubar.org
      admin_server = kerberos.fubar.org
  }

[domain_realm]
   .mit.edu = ATHENA.MIT.EDU
   mit.edu = ATHENA.MIT.EDU

Example 2 KDC Using the LDAP KDB plug-in, `realms` and `dbmodules` Sections

The following is an example of the realms and dbmodules sections of a Kerberos configuration file when the KDC is using the LDAP KDB plug-in.

[realms]
    SUN.COM = {
        kdc = kc-umpk-01.athena.mit.edu
        kdc = kc-umpk-02.athena.mit.edu
        admin_server = kc-umpk-01.athena.mit.edu
        database_module = LDAP
    }

[dbmodules]
    LDAP = {
        db_library = kdb_ldap
        ldap_kerberos_container_dn = "cn=krbcontainer,dc=mit,dc=edu"
        ldap_kdc_dn = "cn=kdc service,ou=profile,dc=mit,dc=edu"
        ldap_kadmind_dn = "cn=kadmin service,ou=profile,dc=mit,dc=edu"
        ldap_cert_path = /var/ldap
        ldap_servers = ldaps://ds.mit.edu
    }

Files

/var/krb5/kdc.log: KDC logging file

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface Stability	See below.

All of the keywords are Committed, except for the PKINIT keywords, which are Volatile.

Notes

If the krb5.conf file is not formatted properly, the telnet command fails. However, the dtlogin and login commands still succeed, even if the krb5.conf file is specified as required for the commands. If this occurs, the following error message is displayed:

Error initializing krb5: Improper format of item

To bypass any other problems that might occur, you should fix the file as soon as possible.

The max_life and max_renewable_life options are obsolete and is removed in a future release of the Solaris operating system.

SunOS 5.11 Last Revised 5 Jan 2009

krb5.conf(4)

Name

Synopsis

Description

The [libdefaults] Section

The [appdefaults] Section

The [realms] Section

The [domain_realm] Section

The [logging] Section

The [capaths] Section

PKINIT-specific Options

PKINIT URI Types

The [dbmodules] Section

Examples

Example 1 Sample File

Example 2 KDC Using the LDAP KDB plug-in, realms and dbmodules Sections

Files

Attributes

See Also

Notes

The `[libdefaults]` Section

The `[appdefaults]` Section

The `[realms]` Section

The `[domain_realm]` Section

The `[logging]` Section

The `[capaths]` Section

The `[dbmodules]` Section

Example 2 KDC Using the LDAP KDB plug-in, `realms` and `dbmodules` Sections