.\"	$NetBSD: krb5.conf.5,v 1.7 2023/06/19 21:41:44 christos Exp $
.\"
.\" Copyright (c) 1999 - 2005 Kungliga Tekniska Högskolan
.\" (Royal Institute of Technology, Stockholm, Sweden).
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\"
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\"
.\" 3. Neither the name of the Institute nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" Id
.\"
.Dd May  4, 2005
.Dt KRB5.CONF 5
.Os
.Sh NAME
.Nm krb5.conf
.Nd configuration file for Kerberos 5
.Sh SYNOPSIS
.In krb5/krb5.h
.Sh DESCRIPTION
The
.Nm
file specifies several configuration parameters for the Kerberos 5
library, as well as for some programs.
.Pp
The file consists of one or more sections, containing a number of
bindings.
The value of each binding can be either a string or a list of other
bindings.
The grammar looks like:
.Bd -literal -offset indent
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

.Ed
.Li STRINGs
consists of one or more non-whitespace characters.
.Pp
STRINGs that are specified later in this man-page uses the following
notation.
.Bl -tag -width "xxx" -offset indent
.It boolean
values can be either yes/true or no/false.
.It 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.
.It 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 .
.It address
an address can be either a IPv4 or a IPv6 address.
.El
.Pp
Currently recognised sections and bindings are:
.Bl -tag -width "xxx" -offset indent
.It Li [appdefaults]
Specifies the default values to be used for Kerberos applications.
You can specify defaults per application, realm, or a combination of
these.
The preference order is:
.Bl -enum -compact
.It
.Va application Va realm Va option
.It
.Va application Va option
.It
.Va realm Va option
.It
.Va option
.El
.Pp
The supported options are:
.Bl -tag -width "xxx" -offset indent
.It Li forwardable = Va boolean
When obtaining initial credentials, make the credentials forwardable.
.It Li proxiable = Va boolean
When obtaining initial credentials, make the credentials proxiable.
.It Li no-addresses = Va boolean
When obtaining initial credentials, request them for an empty set of
addresses, making the tickets valid from any address.
.It Li ticket_lifetime = Va time
Default ticket lifetime.
.It Li renew_lifetime = Va time
Default renewable ticket lifetime.
.It Li encrypt = Va boolean
Use encryption, when available.
.It Li forward = Va boolean
Forward credentials to remote host (for
.Xr rsh 1 ,
.Xr telnet 1 ,
etc).
.It Li historical_anon_pkinit = Va boolean
Enable legacy anonymous pkinit command-line syntax.
With this option set to
.Li true,
the
.Xr kinit 1
.Fl Fl anonymous
command with no principal argument specified will request an anonymous pkinit
ticket from the default realm.
If a principal argument is specified, it is used as an explicit realm name for
anonymous pkinit even without an
.Li @
prefix.
.El
.It Li [libdefaults]
.Bl -tag -width "xxx" -offset indent
.It Li default_realm = Va REALM
Default realm to use, this is also known as your
.Dq local realm .
The default is the result of
.Fn krb5_get_host_realm "local hostname" .
.It Li allow_weak_crypto = Va boolean
are weak crypto algorithms allowed to be used, among others, DES is
considered weak.
.It Li clockskew = Va time
Maximum time differential (in seconds) allowed when comparing
times.
Default is 300 seconds (five minutes).
.It Li kdc_timeout = Va time
Maximum time to wait for a reply from the kdc, default is 3 seconds.
.It Li capath = {
.Bl -tag -width "xxx" -offset indent
.It Va destination-realm Li = Va next-hop-realm
.It ...
.It Li }
.El
This is deprecated, see the
.Li capaths
section below.
.It Li default_cc_type = Va cctype
sets the default credentials type.
.It Li default_cc_name = Va ccname
the default credentials cache name.
If you want to change the type only use
.Li default_cc_type .
The string can contain variables that are expanded on runtime.
The Only supported variable currently is
.Li %{uid}
which expands to the current user id.
.It Li default_etypes = Va etypes ...
A list of default encryption types to use. (Default: all enctypes if
allow_weak_crypto = TRUE, else all enctypes except single DES enctypes.)
.It Li default_as_etypes = Va etypes ...
A list of default encryption types to use in AS requests.  (Default: the
value of default_etypes.)
.It Li default_tgs_etypes = Va etypes ...
A list of default encryption types to use in TGS requests.  (Default:
the value of default_etypes.)
.It Li default_etypes_des = Va etypes ...
A list of default encryption types to use when requesting a DES credential.
.It Li default_keytab_name = Va keytab
The keytab to use if no other is specified, default is
.Dq FILE:/etc/krb5.keytab .
.It Li dns_lookup_kdc = Va boolean
Use DNS SRV records to lookup KDC services location.
.It Li dns_lookup_realm = Va boolean
Use DNS TXT records to lookup domain to realm mappings.
.It Li kdc_timesync = Va boolean
Try to keep track of the time differential between the local machine
and the KDC, and then compensate for that when issuing requests.
.It Li max_retries = Va number
The max number of times to try to contact each KDC.
.It Li large_msg_size = Va number
The threshold where protocols with tiny maximum message sizes are not
considered usable to send messages to the KDC.
.It Li ticket_lifetime = Va time
Default ticket lifetime.
.It Li renew_lifetime = Va time
Default renewable ticket lifetime.
.It Li forwardable = Va boolean
When obtaining initial credentials, make the credentials forwardable.
This option is also valid in the [realms] section.
.It Li proxiable = Va boolean
When obtaining initial credentials, make the credentials proxiable.
This option is also valid in the [realms] section.
.It Li verify_ap_req_nofail = Va boolean
If enabled, failure to verify credentials against a local key is a
fatal error.
The application has to be able to read the corresponding service key
for this to work.
Some applications, like
.Xr su 1 ,
enable this option unconditionally.
.It Li warn_pwexpire = Va time
How soon to warn for expiring password.
Default is seven days.
.It Li http_proxy = Va proxy-spec
A HTTP-proxy to use when talking to the KDC via HTTP.
.It Li dns_proxy = Va proxy-spec
Enable using DNS via HTTP.
.It Li extra_addresses = Va address ...
A list of addresses to get tickets for along with all local addresses.
.It Li time_format = Va string
How to print time strings in logs, this string is passed to
.Xr strftime 3 .
.It Li date_format = Va string
How to print date strings in logs, this string is passed to
.Xr strftime 3 .
.It Li log_utc = Va boolean
Write log-entries using UTC instead of your local time zone.
.It Li scan_interfaces = Va boolean
Scan all network interfaces for addresses, as opposed to simply using
the address associated with the system's host name.
.It Li fcache_version = Va int
Use file credential cache format version specified.
.It Li fcc-mit-ticketflags = Va boolean
Use MIT compatible format for file credential cache.
It's the field ticketflags that is stored in reverse bit order for
older than Heimdal 0.7.
Setting this flag to
.Dv TRUE
makes it store the MIT way, this is default for Heimdal 0.7.
.It Li check-rd-req-server
If set to "ignore", the framework will ignore any of the server input to
.Xr 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.
.It Li k5login_directory = Va directory
Alternative location for user .k5login files. This option is provided
for compatibility with MIT krb5 configuration files.
.It Li k5login_authoritative = Va boolean
If true then if a principal is not found in k5login files then
.Xr krb5_userok 3
will not fallback on principal to username mapping. This option is
provided for compatibility with MIT krb5 configuration files.
.It Li kuserok = Va rule ...
Specifies
.Xr krb5_userok 3
behavior.  If multiple values are given, then
.Xr 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.
.It Li kuserok = Va DENY
If set and evaluated then
.Xr krb5_userok 3
will deny access to the given username no matter what the principal name
might be.
.It Li kuserok = Va SIMPLE
If set and evaluated then
.Xr 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.
.It Li kuserok = Va SYSTEM-K5LOGIN[:directory]
If set and evaluated then
.Xr krb5_userok 3
will use k5login files named after the
.Va luser
argument to
.Xr krb5_userok 3
in the given directory or in
.Pa /etc/k5login.d/ .
K5login files are text files, with each line containing just a principal
name; principals apearing in a user's k5login file are permitted access
to the user's account. Note: this rule performs no ownership nor
permissions checks on k5login files; proper ownership and
permissions/ACLs are expected due to the k5login location being a
system location.
.It Li kuserok = Va USER-K5LOGIN
If set and evaluated then
.Xr krb5_userok 3
will use
.Pa ~luser/.k5login
and
.Pa ~luser/.k5login.d/* .
User k5login files and directories must be owned by the user and must
not have world nor group write permissions.
.It Li aname2lname-text-db = Va filename
The named file must be a sorted (in increasing order) text file where
every line consists of an unparsed principal name optionally followed by
whitespace and a username.  The aname2lname function will do a binary
search on this file, if configured, looking for lines that match the
given principal name, and if found the given username will be used, or,
if the username is missing, an error will be returned.  If the file
doesn't exist, or if no matching line is found then other plugins will
be allowed to run.
.It Li fcache_strict_checking
strict checking in FILE credential caches that owner, no symlink and
permissions is correct.
.It Li name_canon_rules = Va rules
One or more service principal name canonicalization rules.  Each rule
consists of one or more tokens separated by colon (':').  Currently
these rules are used only for hostname canonicalization (usually when
getting a service ticket, from a ccache or a TGS, but also when
acquiring GSS initiator credentials from a keytab).  These rules can be
used to implement DNS resolver-like search lists without having to use
DNS.
.Pp
NOTE: Name canonicalization rules are an experimental feature.
.Pp
The first token is a rule type, one of:
.Va as-is,
.Va qualify, or
.Va nss.
.Pp
Any remaining tokens must be options tokens:
.Va use_fast
(use FAST to protect TGS exchanges; currently not supported),
.Va use_dnssec
(use DNSSEC to protect hostname lookups; currently not supported),
.Va ccache_only
,
.Va use_referrals,
.Va no_referrals,
.Va lookup_realm,
.Va mindots=N,
.Va maxdots=N,
.Va order=N,
domain=
.Va domain,
realm=
.Va realm,
match_domain=
.Va domain,
and match_realm=
.Va realm.
.Pp
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.
.Pp
For each rule the system checks that the hostname has at least
.Va mindots
periods (if given) in it, at most
.Va maxdots
periods (if given), that the hostname ends in the given
.Va match_domain
(if given),
and that the realm of the principal matches the
.Va match_realm
(if given).
.Pp
.Va As-is
rules leave the hostname unmodified but may set a realm.
.Va Qualify
rules qualify the hostname with the given
.Va domain
and also may set the realm.
The
.Va nss
rule uses the system resolver to lookup the host's canonical name and is
usually not secure.  Note that using the
.Va nss
rule type implies having to have principal aliases in the HDB (though
not necessarily in keytabs).
.Pp
The empty realm denotes "ask the client's realm's TGS".  The empty realm
may be set as well as matched.
.Pp
The order in which rules are applied is as follows: first all the rules
with explicit
.Va order
then all other rules in the order in which they appear.  If any two
rules have the same explicit
.Va order ,
their order of appearance in krb5.conf breaks the tie.  Explicitly
specifying order can be useful where tools read and write the
configuration file without preserving parameter order.
.Pp
Malformed rules are ignored.
.It Li allow_hierarchical_capaths = Va boolean
When validating cross-realm transit paths, absent any explicit capath from the
client realm to the server realm, allow a hierarchical transit path via the
common ancestor domain of the two realms.
Defaults to true.
Note, absent an explicit setting, hierarchical capaths are always used by
the KDC when generating a referral to a destination with which is no direct
trust.
.El
.It Li [domain_realm]
This is a list of mappings from DNS domain to Kerberos realm.
Each binding in this section looks like:
.Pp
.Dl domain = realm
.Pp
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
.Dq .example.com
matches
.Dq foo.example.com ,
but not
.Dq foo.test.example.com .
.Pp
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).
.It Li [realms]
.Bl -tag -width "xxx" -offset indent
.It Va REALM Li = {
.Bl -tag -width "xxx" -offset indent
.It Li kdc = Va [service/]host[:port]
Specifies a list of kdcs for this realm.
If the optional
.Va port
is absent, the
default value for the
.Dq kerberos/udp
.Dq kerberos/tcp ,
and
.Dq http/tcp
port (depending on service) will be used.
The kdcs will be used in the order that they are specified.
.Pp
The optional
.Va service
specifies over what medium the kdc should be
contacted.
Possible services are
.Dq udp ,
.Dq tcp ,
and
.Dq http .
Http can also be written as
.Dq http:// .
Default service is
.Dq udp
and
.Dq tcp .
.It Li admin_server = Va host[:port]
Specifies the admin server for this realm, where all the modifications
to the database are performed.
.It Li kpasswd_server = Va host[:port]
Points to the server where all the password changes are performed.
If there is no such entry, the kpasswd port on the admin_server host
will be tried.
.It Li tgs_require_subkey
a boolan variable that defaults to false.
Old DCE secd (pre 1.1) might need this to be true.
.It Li auth_to_local_names = {
.Bl -tag -width "xxx" -offset indent
.It Va principal_name = Va username
The given
.Va principal_name
will be mapped to the given
.Va username
if the
.Va REALM
is a default realm.
.El
.It Li }
.It Li auth_to_local = HEIMDAL_DEFAULT
Use the Heimdal default principal to username mapping.
Applies to principals from the
.Va REALM
if and only if
.Va REALM
is a default realm.
.It Li auth_to_local = DEFAULT
Use the MIT default principal to username mapping.
Applies to principals from the
.Va REALM
if and only if
.Va REALM
is a default realm.
.It Li 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
.Va REALM
if and only if
.Va REALM
is a default realm.
.It Li auth_to_local = DB:/path/to/db
Use the given DB, if there's a plugin for it.
Applies to principals from the
.Va REALM
if and only if
.Va REALM
is a default realm.
.It Li auth_to_local = RULE:...
Use the given rule, if there's a plugin for it.
Applies to principals from the
.Va REALM
if and only if
.Va REALM
is a default realm.
.It Li auth_to_local = NONE
No additional principal to username mapping is done. Note that
.Va auth_to_local_names
and any preceding
.Va auth_to_local
rules have precedence.
.El
.It Li }
.El
.It Li [capaths]
.Bl -tag -width "xxx" -offset indent
.It Va client-realm Li = {
.Bl -tag -width "xxx" -offset indent
.It Va server-realm Li = Va hop-realm ...
This serves two purposes. First the first listed
.Va hop-realm
tells a client which realm it should contact in order to ultimately
obtain credentials for a service in the
.Va server-realm .
Secondly, it tells the KDC (and other servers) which realms are
allowed in a multi-hop traversal from
.Va client-realm
to
.Va server-realm .
Except for the client case, the order of the realms are not important.
.El
.It Va }
.El
.It Li [logging]
.Bl -tag -width "xxx" -offset indent
.It Va entity Li = Va destination
Specifies that
.Va entity
should use the specified
.Li destination
for logging.
See the
.Xr krb5_openlog 3
manual page for a list of defined destinations.
.El
.It Li [kdc]
.Bl -tag -width "xxx" -offset indent
.It Li database Li = {
.Bl -tag -width "xxx" -offset indent
.It Li dbname Li = Va [DATBASETYPE:]DATABASENAME
Use this database for this realm.  The
.Va DATABASETYPE
should be one of 'lmdb', 'db3', 'db1', 'db', 'sqlite', or 'ldap'.
See the info documetation how to configure different database backends.
.It Li realm Li = Va REALM
Specifies the realm that will be stored in this database.
It realm isn't set, it will used as the default database, there can
only be one entry that doesn't have a
.Li realm
stanza.
.It Li mkey_file Li = Pa FILENAME
Use this keytab file for the master key of this database.
If not specified
.Va DATABASENAME Ns .mkey
will be used.
.It Li acl_file Li = PA FILENAME
Use this file for the ACL list of this database.
.It Li log_file Li = Pa FILENAME
Use this file as the log of changes performed to the database.
This file is used by
.Nm ipropd-master
for propagating changes to slaves.  It is also used by
.Nm kadmind
and
.Nm kadmin
(when used with the
.Li -l
option), and by all applications using
.Nm libkadm5
with the local backend, for two-phase commit functionality.  Slaves also
use this.  Setting this to
.Nm /dev/null
disables two-phase commit and incremental propagation.  Use
.Nm iprop-log
to show the contents of this log file.
.It Li log-max-size = Pa number
When the log reaches this size (in bytes), the log will be truncated,
saving some entries, and keeping the latest version number so as to not
disrupt incremental propagation.  If set to a negative value then
automatic log truncation will be disabled.  Defaults to 52428800 (50MB).
.El
.It Li }
.It Li max-request = Va SIZE
Maximum size of a kdc request.
.It Li require-preauth = Va BOOL
If set pre-authentication is required.
.It Li ports = Va "list of ports"
List of ports the kdc should listen to.
.It Li addresses = Va "list of interfaces"
List of addresses the kdc should bind to.
.It Li enable-http = Va BOOL
Should the kdc answer kdc-requests over http.
.It Li tgt-use-strongest-session-key = Va BOOL
If this is TRUE then the KDC will prefer the strongest key from the
client's AS-REQ or TGS-REQ enctype list for the ticket session key that
is supported by the KDC and the target principal when the target
principal is a krbtgt principal.  Else it will prefer the first key from
the client's AS-REQ enctype list that is also supported by the KDC and
the target principal.  Defaults to FALSE.
.It Li svc-use-strongest-session-key = Va BOOL
Like tgt-use-strongest-session-key, but applies to the session key
enctype of tickets for services other than krbtgt principals. Defaults
to FALSE.
.It Li preauth-use-strongest-session-key = Va BOOL
If TRUE then select the strongest possible enctype from the client's
AS-REQ for PA-ETYPE-INFO2 (i.e., for password-based pre-authentication).
Else pick the first supported enctype from the client's AS-REQ.  Defaults
to FALSE.
.It Li use-strongest-server-key = Va BOOL
If TRUE then the KDC picks, for the ticket encrypted part's key, the
first supported enctype from the target service principal's hdb entry's
current keyset. Else the KDC picks the first supported enctype from the
target service principal's hdb entry's current keyset.  Defaults to TRUE.
.It Li check-ticket-addresses = Va BOOL
Verify the addresses in the tickets used in tgs requests.
.\" XXX
.It Li allow-null-ticket-addresses = Va BOOL
Allow address-less tickets.
.\" XXX
.It Li allow-anonymous = Va BOOL
If the kdc is allowed to hand out anonymous tickets.
.It Li historical_anon_realm = Va boolean
Enables pre-7.0 non-RFC-comformant KDC behavior.
With this option set to
.Li true
the client realm in anonymous pkinit AS replies will be the requested realm,
rather than the RFC-conformant
.Li WELLKNOWN:ANONYMOUS
realm.
This can have a security impact on servers that expect to grant access to
anonymous-but-authenticated to the KDC users of the realm in question:
they would also grant access to unauthenticated anonymous users.
As such, it is not recommend to set this option to
.Li true.
.It Li encode_as_rep_as_tgs_rep = Va BOOL
Encode as-rep as tgs-rep to be compatible with mistakes older DCE secd did.
.\" XXX
.It Li kdc_warn_pwexpire = Va TIME
The time before expiration that the user should be warned that her
password is about to expire.
.It Li logging = Va Logging
What type of logging the kdc should use, see also [logging]/kdc.
.It Li hdb-ldap-structural-object Va structural object
If the LDAP backend is used for storing principals, this is the
structural object that will be used when creating and when reading
objects.
The default value is account .
.It Li hdb-ldap-create-base Va creation dn
is the dn that will be appended to the principal when creating entries.
Default value is the search dn.
.It Li enable-digest = Va BOOL
Should the kdc answer digest requests. The default is FALSE.
.It Li digests_allowed = Va list of digests
Specifies the digests the kdc will reply to. The default is
.Li ntlm-v2 .
.It Li kx509_ca = Va file
Specifies the PEM credentials for the kx509 certification authority.
.It Li require_initial_kca_tickets = Va boolean
Specified whether to require that tickets for the
.Li 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.
.It Li kx509_include_pkinit_san = Va boolean
If true then the kx509 client principal's name and realm will be
included in an
.Li id-pkinit-san
certificate extension.
This can be set on a per-realm basis as well as globally.
Defaults to true for the global setting.
.It Li kx509_template = Va file
Specifies the PEM file with a template for the certificates to be
issued.
The following variables can be interpolated in the subject name using
${variable} syntax:
.Bl -tag -width "xxx" -offset indent
.It principal-name
The full name of the kx509 client principal.
.It principal-name-without-realm
The full name of the kx509 client principal, excluding the realm name.
.It principal-name-realm
The name of the client principal's realm.
.El
.El
The 
.Li kx509 ,
.Li kx509_template ,
.Li kx509_include_pkinit_san ,
and
.Li require_initial_kca_tickets
parameters may be set on a per-realm basis as well.
.It Li [kadmin]
.Bl -tag -width "xxx" -offset indent
.It Li password_lifetime = Va time
If a principal already have its password set for expiration, this is
the time it will be valid for after a change.
.It Li default_keys = Va keytypes...
For each entry in
.Va default_keys
try to parse it as a sequence of
.Va etype:salttype:salt
syntax of this if something like:
.Pp
[(des|des3|etype):](pw-salt|afs3-salt)[:string]
.Pp
If
.Ar etype
is omitted it means everything, and if string is omitted it means the
default salt string (for that principal and encryption type).
Additional special values of keytypes are:
.Bl -tag -width "xxx" -offset indent
.It Li v5
The Kerberos 5 salt
.Va pw-salt
.El
.It Li default_key_rules = Va {
.Bl -tag -width "xxx" -offset indent
.It Va globing-rule Li = Va keytypes...
a globbing rule to matching a principal, and when true, use the
keytypes as specified the same format as [kadmin]default_keys .
.El
.It Li }
.It Li prune-key-history = Va BOOL
When adding keys to the key history, drop keys that are too old to match
unexpired tickets (based on the principal's maximum ticket lifetime).
If the KDC keystore is later compromised traffic protected with the
discarded older keys may remain protected.  This also keeps the HDB
records for principals with key history from growing without bound.
The default (backwards compatible) value is "false".
.It Li use_v4_salt = Va BOOL
When true, this is the same as
.Pp
.Va default_keys = Va des3:pw-salt Va v4
.Pp
and is only left for backwards compatibility.
.It Li [password_quality]
Check the Password quality assurance in the info documentation for
more information.
.Bl -tag -width "xxx" -offset indent
.It Li check_library = Va library-name
Library name that contains the password check_function
.It Li check_function = Va function-name
Function name for checking passwords in check_library
.It Li policy_libraries = Va library1 ... libraryN
List of libraries that can do password policy checks
.It Li policies = Va policy1 ... policyN
List of policy names to apply to the password. Builtin policies are
among other minimum-length, character-class, external-check.
.El
.El
.El
.Sh ENVIRONMENT
.Ev KRB5_CONFIG
points to the configuration file to read.
.Sh FILES
.Bl -tag -width "/etc/krb5.conf"
.It Pa /etc/krb5.conf
configuration file for Kerberos 5.
.El
.Sh EXAMPLES
.Bd -literal -offset indent
[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
	}
.Ed
.Sh DIAGNOSTICS
Since
.Nm
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
.Nm verify_krb5_conf
that reads
.Nm
and tries to emit useful diagnostics from parsing errors.
Note that this program does not have any way of knowing what options
are actually used and thus cannot warn about unknown or misspelled
ones.
.Sh SEE ALSO
.Xr kinit 1 ,
.Xr krb5_openlog 3 ,
.Xr strftime 3 ,
.Xr verify_krb5_conf 8