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<!DOCTYPE reference PUBLIC "-//OASIS//DTD DocBook V4.4//EN"

"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">

<reference>

<title>SSSD Manual pages</title>

<refentry>

<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="include/upstream.xml" />

<refmeta>

<refentrytitle>sssd-krb5</refentrytitle>

<manvolnum>5</manvolnum>

<refmiscinfo class="manual">File Formats and Conventions</refmiscinfo>

</refmeta>

<refnamediv id='name'>

<refname>sssd-krb5</refname>

<refpurpose>the configuration file for SSSD</refpurpose>

</refnamediv>

<refsect1 id='description'>

<title>DESCRIPTION</title>

<para>

This manual page describes the configuration of the Kerberos

5 authentication backend for

<citerefentry>

<refentrytitle>sssd</refentrytitle>

<manvolnum>8</manvolnum>

</citerefentry>.

For a detailed syntax reference, please refer to the <quote>FILE FORMAT</quote> section of the

<citerefentry>

<refentrytitle>sssd.conf</refentrytitle>

<manvolnum>5</manvolnum>

</citerefentry> manual page.

</para>

<para>

The Kerberos 5 authentication backend contains auth and chpass

providers. It must be paired with an identity provider in

order to function properly (for example, id_provider = ldap). Some

information required by the Kerberos 5 authentication backend must

be provided by the identity provider, such as the user's Kerberos

Principal Name (UPN). The configuration of the identity provider

should have an entry to specify the UPN. Please refer to the man

page for the applicable identity provider for details on how to

configure this.

</para>

<para>

This backend also provides access control based on the .k5login

file in the home directory of the user. See <citerefentry>

<refentrytitle>.k5login</refentrytitle><manvolnum>5</manvolnum>

</citerefentry> for more details. Please note that an empty .k5login

file will deny all access to this user. To activate this feature,

use 'access_provider = krb5' in your SSSD configuration.

</para>

<para>

In the case where the UPN is not available in the identity backend,

<command>sssd</command> will construct a UPN using the format

<replaceable>username</replaceable>@<replaceable>krb5_realm</replaceable>.

</para>

</refsect1>

<refsect1 id='file-format'>

<title>CONFIGURATION OPTIONS</title>

<para>

If the auth-module krb5 is used in an SSSD domain, the following

options must be used. See the

<citerefentry>

<refentrytitle>sssd.conf</refentrytitle>

<manvolnum>5</manvolnum>

</citerefentry> manual page, section <quote>DOMAIN SECTIONS</quote>,

for details on the configuration of an SSSD domain.

<variablelist>

<varlistentry>

<term>krb5_server, krb5_backup_server (string)</term>

<listitem>

<para>

Specifies the comma-separated list of IP addresses or hostnames

of the Kerberos servers to which SSSD should

connect, in the order of preference. For more

information on failover and server redundancy,

see the <quote>FAILOVER</quote> section. An optional

port number (preceded by a colon) may be appended to

the addresses or hostnames.

If empty, service discovery is enabled;

for more information, refer to the

<quote>SERVICE DISCOVERY</quote> section.

</para>

<para>

When using service discovery for KDC or kpasswd servers,

SSSD first searches for DNS entries that specify _udp as

the protocol and falls back to _tcp if none are found.

</para>

<para>

This option was named <quote>krb5_kdcip</quote> in

earlier releases of SSSD. While the legacy name is recognized

for the time being, users are advised to migrate their config

files to use <quote>krb5_server</quote> instead.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_realm (string)</term>

<listitem>

<para>

The name of the Kerberos realm. This option is required

and must be specified.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_kpasswd, krb5_backup_kpasswd (string)</term>

<listitem>

<para>

If the change password service is not running on the

KDC, alternative servers can be defined here. An

optional port number (preceded by a colon) may be

appended to the addresses or hostnames.

</para>

<para>

For more information on failover and server

redundancy, see the <quote>FAILOVER</quote> section.

NOTE: Even if there are no more kpasswd

servers to try, the backend is not switched to operate offline

if authentication against the KDC is still possible.

</para>

<para>

Default: Use the KDC

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_ccachedir (string)</term>

<listitem>

<para>

Directory to store credential caches. All the

substitution sequences of krb5_ccname_template can

be used here, too, except %d and %P. If the

directory does not exist, it will be created. If %u,

%U, %p or %h are used, a private directory belonging

to the user is created. Otherwise, a public directory

with restricted deletion flag (aka sticky bit, as

described in

<citerefentry>

<refentrytitle>chmod</refentrytitle>

<manvolnum>1</manvolnum>

</citerefentry> for details) is created.

</para>

<para>

Default: /tmp

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_ccname_template (string)</term>

<listitem>

<para>

Location of the user's credential cache. Two credential

cache types are currently supported: <quote>FILE</quote>

and <quote>DIR</quote>. The cache can be specified either

as <replaceable>TYPE:RESIDUAL</replaceable>, or as an absolute

path, which implies the <quote>FILE</quote> type. In the

template, the following sequences are substituted:

<variablelist>

<varlistentry>

<term>%u</term>

<listitem><para>login name</para></listitem>

</varlistentry>

<varlistentry>

<term>%U</term>

<listitem><para>login UID</para></listitem>

</varlistentry>

<varlistentry>

<term>%p</term>

<listitem><para>principal name</para>

</listitem>

</varlistentry>

<varlistentry>

<term>%r</term>

<listitem><para>realm name</para></listitem>

</varlistentry>

<varlistentry>

<term>%h</term>

<listitem><para>home directory</para>

</listitem>

</varlistentry>

<varlistentry>

<term>%d</term>

<listitem><para>value of krb5ccache_dir

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>%P</term>

<listitem><para>the process ID of the SSSD

client</para>

</listitem>

</varlistentry>

<varlistentry>

<term>%%</term>

<listitem><para>a literal '%'</para>

</listitem>

</varlistentry>

</variablelist>

If the template ends with 'XXXXXX' mkstemp(3) is

used to create a unique filename in a safe way.

</para>

<para>

Default: FILE:%d/krb5cc_%U_XXXXXX

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_auth_timeout (integer)</term>

<listitem>

<para>

Timeout in seconds after an online authentication request

or change password request is aborted. If possible, the

authentication request is continued offline.

</para>

<para>

Default: 6

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_validate (boolean)</term>

<listitem>

<para>

Verify with the help of krb5_keytab that the TGT

obtained has not been spoofed. The keytab is checked for

entries sequentially, and the first entry with a matching

realm is used for validation. If no entry matches the realm, the last

entry in the keytab is used. This process can be used to validate

environments using cross-realm trust by placing the appropriate

keytab entry as the last entry or the only entry in the keytab file.

</para>

<para>

Default: false

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_keytab (string)</term>

<listitem>

<para>

The location of the keytab to use when validating

credentials obtained from KDCs.

</para>

<para>

Default: /etc/krb5.keytab

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_store_password_if_offline (boolean)</term>

<listitem>

<para>

Store the password of the user if the provider is

offline and use it to request a TGT when the

provider comes online again.

</para>

<para>

NOTE: this feature is only available on Linux.

Passwords stored in this way are kept in

plaintext in the kernel keyring and are

potentially accessible by the root user

(with difficulty).

</para>

<para>

Default: false

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_renewable_lifetime (string)</term>

<listitem>

<para>

Request a renewable ticket with a total

lifetime, given as an integer immediately followed

by a time unit:

</para>

<para>

<emphasis>s</emphasis> for seconds

</para>

<para>

<emphasis>m</emphasis> for minutes

</para>

<para>

<emphasis>h</emphasis> for hours

</para>

<para>

<emphasis>d</emphasis> for days.

</para>

<para>

If there is no unit given, <emphasis>s</emphasis> is

assumed.

</para>

<para>

NOTE: It is not possible to mix units. To set

the renewable lifetime to one and a half hours,

use '90m' instead of '1h30m'.

</para>

<para>

Default: not set, i.e. the TGT is not renewable

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_lifetime (string)</term>

<listitem>

<para>

Request ticket with a with a lifetime, given as an

integer immediately followed by a time unit:

</para>

<para>

<emphasis>s</emphasis> for seconds

</para>

<para>

<emphasis>m</emphasis> for minutes

</para>

<para>

<emphasis>h</emphasis> for hours

</para>

<para>

<emphasis>d</emphasis> for days.

</para>

<para>

If there is no unit given <emphasis>s</emphasis> is

assumed.

</para>

<para>

NOTE: It is not possible to mix units.

To set the lifetime to one and a half

hours please use '90m' instead of '1h30m'.

</para>

<para>

Default: not set, i.e. the default ticket lifetime

configured on the KDC.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_renew_interval (integer)</term>

<listitem>

<para>

The time in seconds between two checks if the TGT

should be renewed. TGTs are renewed if about half

of their lifetime is exceeded.

</para>

<para>

If this option is not set or is 0 the automatic

renewal is disabled.

</para>

<para>

Default: not set

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_use_fast (string)</term>

<listitem>

<para>

Enables flexible authentication secure tunneling

(FAST) for Kerberos pre-authentication. The

following options are supported:

</para>

<para>

<emphasis>never</emphasis> use FAST. This is

equivalent to not setting this option at all.

</para>

<para>

<emphasis>try</emphasis> to use FAST. If the server

does not support FAST, continue the

authentication without it.

</para>

<para>

<emphasis>demand</emphasis> to use FAST. The

authentication fails if the server does not

require fast.

</para>

<para>

Default: not set, i.e. FAST is not used.

</para>

<para>

NOTE: a keytab is required to use FAST.

</para>

<para>

NOTE: SSSD supports FAST only with

MIT Kerberos version 1.8 and later. If SSSD is used

with an older version of MIT Kerberos, using this

option is a configuration error.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_fast_principal (string)</term>

<listitem>

<para>

Specifies the server principal to use for FAST.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>krb5_canonicalize (boolean)</term>

<listitem>

<para>

Specifies if the host and user principal should be

canonicalized. This feature is available with MIT

Kerberos 1.7 and later versions.

</para>

<para>

Default: false

</para>

</listitem>

</varlistentry>

</variablelist>

</para>

</refsect1>

<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="include/failover.xml" />

<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="include/service_discovery.xml" />

<refsect1 id='example'>

<title>EXAMPLE</title>

<para>

The following example assumes that SSSD is correctly

configured and FOO is one of the domains in the

<replaceable>[sssd]</replaceable> section. This example shows

only configuration of Kerberos authentication; it does not include

any identity provider.

</para>

<para>

<programlisting>

[domain/FOO]

auth_provider = krb5

krb5_server = 192.168.1.1

krb5_realm = EXAMPLE.COM

</programlisting>

</para>

</refsect1>

<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="include/seealso.xml" />

</refentry>

</reference>