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<?xml version="1.0" encoding="UTF-8"?>
<!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 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 a 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 a 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.
Please note that even if there are no more kpasswd
servers to try the back end is not switch to 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, see
<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 either be specified
as <replaceable>TYPE:RESIDUAL</replaceable>, or 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 or
change password request is aborted. If possible the
authentication request is continued offline.
</para>
<para>
Default: 15
</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 matching
realm is used for validation. If no entry matches the last
one is used. This can be utilized to achieve validation in
enviroments with cross-realm trust by placing appropriate
keytab entry as the last one or the only one.
</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 gets online again.
</para>
<para>
Please note that this feature currently only
available on a Linux platform. 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 by an integer immediately followed
by one of the following delimiters:
</para>
<para>
<emphasis>s</emphasis> seconds
</para>
<para>
<emphasis>m</emphasis> minutes
</para>
<para>
<emphasis>h</emphasis> hours
</para>
<para>
<emphasis>d</emphasis> days.
</para>
<para>
If there is no delimiter <emphasis>s</emphasis> is
assumed.
</para>
<para>
Please note that it is not possible to mix units.
If you want to set the renewable lifetime to one
and a half hours please 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 by an
integer immediately followed by one of the following
delimiters:
</para>
<para>
<emphasis>s</emphasis> seconds
</para>
<para>
<emphasis>m</emphasis> minutes
</para>
<para>
<emphasis>h</emphasis> hours
</para>
<para>
<emphasis>d</emphasis> days.
</para>
<para>
If there is no delimiter <emphasis>s</emphasis> is
assumed.
</para>
<para>
Please note that it is not possible to mix units.
If you want 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 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 set this option at all.
</para>
<para>
<emphasis>try</emphasis> to use FAST, if the server
does not support fast continue without.
</para>
<para>
<emphasis>demand</emphasis> to use FAST, fail if the
server does not require fast.
</para>
<para>
Default: not set, i.e. FAST is not used.
</para>
<para>
Please note that a keytab is required to use fast.
</para>
<para>
Please note also that sssd supports fast only with
MIT Kerberos version 1.8 and above. If sssd used
with an older version 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
</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>
|
