PAM_SSS_GSS(8) SSSD Manual pages PAM_SSS_GSS(8)
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
SEE ALSO
sssd(8), sssd.conf(5), sssd-ldap(5), sssd-krb5(5), sssd-simple(5),
sssd-ipa(5), sssd-ad(5), sssd-files(5), sssd-sudo(5), sssd-session-
recording(5), sss_cache(8), sss_debuglevel(8), sss_obfuscate(8),
sss_seed(8), sssd_krb5_locator_plugin(8), sss_ssh_authorizedkeys(8),
sss_ssh_knownhostsproxy(8), sssd-ifp(5), pam_sss(8). sss_rpcidmapd(5)
sssd-systemtap(5)
AUTHORS
The SSSD upstream - https://github.com/SSSD/sssd/
SSSD 06/07/2024 PAM_SSS_GSS(8)
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