Ubuntu Manpage: pam_sss_gss - PAM module for SSSD GSSAPI authentication

Provided by: libpam-sss_2.8.1-1ubuntu1_amd64

NAME

       pam_sss_gss - PAM module for SSSD GSSAPI authentication

SYNOPSIS

       pam_sss_gss.so [debug]

DESCRIPTION

pam_sss_gss.so authenticates user over GSSAPI in cooperation with SSSD.

This module will try to authenticate the user using the GSSAPI hostbased service name
host@hostname which translates to host/hostname@REALM Kerberos principal. The REALM part
of the Kerberos principal name is derived by Kerberos internal mechanisms and it can be
set explicitly in configuration of [domain_realm] section in /etc/krb5.conf.

SSSD is used to provide desired service name and to validate the user's credentials using
GSSAPI calls. If the service ticket is already present in the Kerberos credentials cache
or if user's ticket granting ticket can be used to get the correct service ticket then the
user will be authenticated.

If pam_gssapi_check_upn is True (default) then SSSD requires that the credentials used to
obtain the service tickets can be associated with the user. This means that the principal
that owns the Kerberos credentials must match with the user principal name as defined in
LDAP.

To enable GSSAPI authentication in SSSD, set pam_gssapi_services option in [pam] or domain
section of sssd.conf. The service credentials need to be stored in SSSD's keytab (it is
already present if you use ipa or ad provider). The keytab location can be set with
krb5_keytab option. See sssd.conf(5) and sssd-krb5(5) for more details on these options.

Some Kerberos deployments allow to associate authentication indicators with a particular
pre-authentication method used to obtain the ticket granting ticket by the user.
pam_sss_gss.so allows to enforce presence of authentication indicators in the service
tickets before a particular PAM service can be accessed.

If pam_gssapi_indicators_map is set in the [pam] or domain section of sssd.conf, then SSSD
will perform a check of the presence of any configured indicators in the service ticket.

OPTIONS

       debug
           Print debugging information.

MODULE TYPES PROVIDED

       Only the auth module type is provided.

RETURN VALUES

       PAM_SUCCESS
           The PAM operation finished successfully.

       PAM_USER_UNKNOWN
           The user is not known to the authentication service or the GSSAPI authentication is
           not supported.

       PAM_AUTH_ERR
           Authentication failure.

       PAM_AUTHINFO_UNAVAIL
           Unable to access the authentication information. This might be due to a network or
           hardware failure.

       PAM_SYSTEM_ERR
           A system error occurred. The SSSD log files may contain additional information about
           the error.

EXAMPLES

       The main use case is to provide password-less authentication in sudo but without the need
       to disable authentication completely. To achieve this, first enable GSSAPI authentication
       for sudo in sssd.conf:

           [domain/MYDOMAIN]
           pam_gssapi_services = sudo, sudo-i

       And then enable the module in desired PAM stack (e.g. /etc/pam.d/sudo and
       /etc/pam.d/sudo-i).

           ...
           auth sufficient pam_sss_gss.so
           ...

TROUBLESHOOTING

       SSSD logs, pam_sss_gss debug output and syslog may contain helpful information about the
       error. Here are some common issues:

       1. I have KRB5CCNAME environment variable set and the authentication does not work:
       Depending on your sudo version, it is possible that sudo does not pass this variable to
       the PAM environment. Try adding KRB5CCNAME to env_keep in /etc/sudoers or in your LDAP
       sudo rules default options.

       2. Authentication does not work and syslog contains "Server not found in Kerberos
       database": Kerberos is probably not able to resolve correct realm for the service ticket
       based on the hostname. Try adding the hostname directly to [domain_realm] in
       /etc/krb5.conf like so:

       3. Authentication does not work and syslog contains "No Kerberos credentials available":
       You don't have any credentials that can be used to obtain the required service ticket. Use
       kinit or authenticate over SSSD to acquire those credentials.

       4. Authentication does not work and SSSD sssd-pam log contains "User with UPN [$UPN] was
       not found." or "UPN [$UPN] does not match target user [$username].": You are using
       credentials that can not be mapped to the user that is being authenticated. Try to use
       kswitch to select different principal, make sure you authenticated with SSSD or consider
       disabling pam_gssapi_check_upn.

           [domain_realm]
           .myhostname = MYREALM

AUTHORS

       The SSSD upstream - https://github.com/SSSD/sssd/