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Chapter 52. Kerberos PKINIT authentication in IdM

Public Key Cryptography for Initial Authentication in Kerberos (PKINIT) is a preauthentication mechanism for Kerberos. The Identity Management (IdM) server includes a mechanism for Kerberos PKINIT authentication.

52.1. Default PKINIT configuration

The default PKINIT configuration on your IdM servers depends on the certificate authority (CA) configuration.

Table 52.1. Default PKINIT configuration in IdM

CA configurationPKINIT configuration

Without a CA, no external PKINIT certificate provided

Local PKINIT: IdM only uses PKINIT for internal purposes on servers.

Without a CA, external PKINIT certificate provided to IdM

IdM configures PKINIT by using the external Kerberos key distribution center (KDC) certificate and CA certificate.

With an Integrated CA

IdM configures PKINIT by using the certificate signed by the IdM CA.

52.2. Displaying the current PKINIT configuration

IdM provides multiple commands you can use to query the PKINIT configuration in your domain.

Procedure

  • To determine the PKINIT status in your domain, use the ipa pkinit-status command: 

    $ ipa pkinit-status
  Server name: server1.example.com
  PKINIT status: enabled
  [...output truncated...]
  Server name: server2.example.com
  PKINIT status: disabled
  [...output truncated...]

    The command displays the PKINIT configuration status as enabled or disabled:

    • enabled: PKINIT is configured using a certificate signed by the integrated IdM CA or an external PKINIT certificate.
    • disabled: IdM only uses PKINIT for internal purposes on IdM servers.

  • To list the IdM servers with active Kerberos key distribution centers (KDCs) that support PKINIT for IdM clients, use the ipa config-show command on any server: 

    $ ipa config-show
  Maximum username length: 32
  Home directory base: /home
  Default shell: /bin/sh
  Default users group: ipausers
  [...output truncated...]
  IPA masters capable of PKINIT: server1.example.com
  [...output truncated...]

52.3. Configuring PKINIT in IdM

If your IdM servers are running with PKINIT disabled, use these steps to enable it. For example, a server is running with PKINIT disabled if you passed the --no-pkinit option with the ipa-server-install or ipa-replica-install utilities.

Prerequisites

  • Ensure that all IdM servers with a certificate authority (CA) installed are running on the same domain level.

Procedure

  1. Check if PKINIT is enabled on the server: 

    # kinit admin

Password for admin@IDM.EXAMPLE.COM:
# ipa pkinit-status --server=server.idm.example.com
1 server matched
----------------
Server name: server.idm.example.com
PKINIT status:enabled
----------------------------
Number of entries returned 1
----------------------------

    If PKINIT is disabled, you will see the following output: 

    # ipa pkinit-status --server server.idm.example.com
-----------------
0 servers matched
-----------------
----------------------------
Number of entries returned 0
----------------------------

    You can also use the command to find all the servers where PKINIT is enabled if you omit the --server <server_fqdn> parameter.

  2. If you are using IdM without CA:

    1. On the IdM server, install the CA certificate that signed the Kerberos key distribution center (KDC) certificate: 

      # ipa-cacert-manage install -t CT,C,C ca.pem

    2. To update all IPA hosts, repeat the ipa-certupdate command on all replicas and clients: 

      # ipa-certupdate

    3. Check if the CA certificate has already been added using the ipa-cacert-manage list command. For example: 

      # ipa-cacert-manage list
CN=CA,O=Example Organization
The ipa-cacert-manage command was successful

    4. Use the ipa-server-certinstall utility to install an external KDC certificate. The KDC certificate must meet the following conditions:

      • It is issued with the common name CN=fully_qualified_domain_name,certificate_subject_base.
      • It includes the Kerberos principal krbtgt/REALM_NAME@REALM_NAME.

      • It contains the Object Identifier (OID) for KDC authentication: 1.3.6.1.5.2.3.5. 

        # ipa-server-certinstall --kdc kdc.pem kdc.key

# systemctl restart krb5kdc.service

    5. See your PKINIT status: 

      # ipa pkinit-status
  Server name: server1.example.com
  PKINIT status: enabled
  [...output truncated...]
  Server name: server2.example.com
  PKINIT status: disabled
  [...output truncated...]

  3. If you are using IdM with a CA certificate, enable PKINIT as follows: 

    # ipa-pkinit-manage enable
  Configuring Kerberos KDC (krb5kdc)
  [1/1]: installing X509 Certificate for PKINIT
  Done configuring Kerberos KDC (krb5kdc).
  The ipa-pkinit-manage command was successful

    If you are using an IdM CA, the command requests a PKINIT KDC certificate from the CA.

Additional resources

  • ipa-server-certinstall(1) man page

52.4. Additional resources