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Chapter 1. Logging in to Identity Management from the command line

Identity Management (IdM) uses the Kerberos protocol to support single sign-on. Single sign-on means that the user enters the correct user name and password only once, and then accesses IdM services without the system prompting for the credentials again.

Important

In IdM, the System Security Services Daemon (SSSD) automatically obtains a ticket-granting ticket (TGT) for a user after the user successfully logs in to the desktop environment on an IdM client machine with the corresponding Kerberos principal name. This means that after logging in, the user is not required to use the kinit utility to access IdM resources.

If you have cleared your Kerberos credential cache or your Kerberos TGT has expired, you need to request a Kerberos ticket manually to access IdM resources. The following sections present basic user operations when using Kerberos in IdM.

1.1. Using kinit to log in to IdM manually

Follow this procedure to use the kinit utility to authenticate to an Identity Management (IdM) environment manually. The kinit utility obtains and caches a Kerberos ticket-granting ticket (TGT) on behalf of an IdM user.

Note

Only use this procedure if you have destroyed your initial Kerberos TGT or if it has expired. As an IdM user, when logging onto your local machine you are also automatically logging in to IdM. This means that after logging in, you are not required to use the kinit utility to access IdM resources.

Procedure

  1. To log in to IdM

    • Under the user name of the user who is currently logged in on the local system, use kinit without specifying a user name. For example, if you are logged in as example_user on the local system: 

      [example_user@server ~]$ kinit
Password for example_user@EXAMPLE.COM:
[example_user@server ~]$

      If the user name of the local user does not match any user entry in IdM, the authentication attempt fails: 

      [example_user@server ~]$ kinit
kinit: Client 'example_user@EXAMPLE.COM' not found in Kerberos database while getting initial credentials

    • Using a Kerberos principal that does not correspond to your local user name, pass the required user name to the kinit utility. For example, to log in as the admin user: 

      [example_user@server ~]$ kinit admin
Password for admin@EXAMPLE.COM:
[example_user@server ~]$

  2. Optionally, to verify that the login was successful, use the klist utility to display the cached TGT. In the following example, the cache contains a ticket for the example_user principal, which means that on this particular host, only example_user is currently allowed to access IdM services: 

    $ klist
Ticket cache: KEYRING:persistent:0:0
Default principal: example_user@EXAMPLE.COM

Valid starting     	Expires            	Service principal
11/10/2019 08:35:45  	11/10/2019 18:35:45  	krbtgt/EXAMPLE.COM@EXAMPLE.COM

1.2. Destroying a user’s active Kerberos ticket

Follow this procedure to clear the credentials cache that contains the user’s active Kerberos ticket.

Procedure

  1. To destroy your Kerberos ticket: 

    [example_user@server ~]$ kdestroy

  2. Optionally, to check that the Kerberos ticket has been destroyed: 

    [example_user@server ~]$ klist
klist: Credentials cache keyring 'persistent:0:0' not found

1.3. Configuring an external system for Kerberos authentication

Follow this procedure to configure an external system so that Identity Management (IdM) users can log in to IdM from the external system using their Kerberos credentials.

Enabling Kerberos authentication on external systems is especially useful when your infrastructure includes multiple realms or overlapping domains. It is also useful if the system has not been enrolled into any IdM domain through ipa-client-install.

To enable Kerberos authentication to IdM from a system that is not a member of the IdM domain, define an IdM-specific Kerberos configuration file on the external system.

Prerequisites

  • The krb5-workstation package is installed on the external system.

    To find out whether the package is installed, use the following CLI command: 

    # yum list installed krb5-workstation
Installed Packages
krb5-workstation.x86_64    1.16.1-19.el8     @BaseOS

Procedure

  1. Copy the /etc/krb5.conf file from the IdM server to the external system. For example: 

    # scp /etc/krb5.conf root@externalsystem.example.com:/etc/krb5_ipa.conf
    Warning

    Do not overwrite the existing krb5.conf file on the external system.

  2. On the external system, set the terminal session to use the copied IdM Kerberos configuration file: 

    $ export KRB5_CONFIG=/etc/krb5_ipa.conf

    The KRB5_CONFIG variable exists only temporarily until you log out. To prevent this loss, export the variable with a different file name.

  3. Copy the Kerberos configuration snippets from the /etc/krb5.conf.d/ directory to the external system.

Users on the external system can now use the kinit utility to authenticate against the IdM server.

1.4. Additional resources

  • The krb5.conf(5) man page.
  • The kinit(1) man page.
  • The klist(1) man page.
  • The kdestroy(1) man page.