---
name: "pam_sss"
section: "8"
platform: "linux"
package: "sssd"
version: "2.13.1-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/pam_sss"
---

# pam\_sss(8)

PAM module for SSSD

## NAME

pam\_sss - PAM module for SSSD

## SYNOPSIS

**pam\_sss.so** \[*quiet*\] \[*forward\_pass*\] \[*use\_first\_pass*\] \[*use\_authtok*\] \[*retry=N*\] \[*ignore\_unknown\_user*\] \[*ignore\_authinfo\_unavail*\] \[*domains=X*\] \[*allow\_missing\_name*\] \[*prompt\_always*\] \[*try\_cert\_auth*\] \[*require\_cert\_auth*\] \[*allow\_chauthtok\_by\_root*\]

## DESCRIPTION

**pam\_sss.so** is the PAM interface to the System Security Services daemon (SSSD). Errors and results are logged through **[syslog(3)](/syslog/3.md)** with the LOG\_AUTHPRIV facility.

## OPTIONS

**quiet**

Suppress log messages for unknown users.

**forward\_pass**

If **forward\_pass** is set the entered password is put on the stack for other PAM modules to use.

**use\_first\_pass**

The argument use\_first\_pass forces the module to use a previous stacked modules password and will never prompt the user - if no password is available or the password is not appropriate, the user will be denied access.

**use\_authtok**

When password changing enforce the module to set the new password to the one provided by a previously stacked password module.

**retry=N**

If specified the user is asked another N times for a password if authentication fails. Default is 0.

Please note that this option might not work as expected if the application calling PAM handles the user dialog on its own. A typical example is **sshd** with **PasswordAuthentication**.

**ignore\_unknown\_user**

If this option is specified and the user does not exist, the PAM module will return PAM\_IGNORE. This causes the PAM framework to ignore this module.

**ignore\_authinfo\_unavail**

Specifies that the PAM module should return PAM\_IGNORE if it cannot contact the SSSD daemon. This causes the PAM framework to ignore this module.

**domains**

Allows the administrator to restrict the domains a particular PAM service is allowed to authenticate against. The format is a comma-separated list of SSSD domain names, as specified in the sssd.conf file.

NOTE: If this is used for a service not running as root user, e.g. a web-server, it must be used in conjunction with the “pam\_trusted\_users” and “pam\_public\_domains” options. Please see the [**sssd.conf**(5)](/sssd.conf/5.md) manual page for more information on these two PAM responder options.

**allow\_missing\_name**

The main purpose of this option is to let SSSD determine the user name based on additional information, e.g. the certificate from a Smartcard.

The current use case are login managers which can monitor a Smartcard reader for card events. In case a Smartcard is inserted the login manager will call a PAM stack which includes a line like

```
auth sufficient pam_sss.so allow_missing_name
```

In this case SSSD will try to determine the user name based on the content of the Smartcard, returns it to pam\_sss which will finally put it on the PAM stack.

**prompt\_always**

Always prompt the user for credentials. With this option credentials requested by other PAM modules, typically a password, will be ignored and pam\_sss will prompt for credentials again. Based on the pre-auth reply by SSSD pam\_sss might prompt for a password, a Smartcard PIN or other credentials.

**try\_cert\_auth**

Try to use certificate based authentication, i.e. authentication with a Smartcard or similar devices. If a Smartcard is available and the service is allowed for Smartcard authentication the user will be prompted for a PIN and the certificate based authentication will continue

If no Smartcard is available or certificate based authentication is not allowed for the current service PAM\_AUTHINFO\_UNAVAIL is returned.

**require\_cert\_auth**

Do certificate based authentication, i.e. authentication with a Smartcard or similar devices. If a Smartcard is not available the user will be prompted to insert one. SSSD will wait for a Smartcard until the timeout defined by p11\_wait\_for\_card\_timeout passed, please see [**sssd.conf**(5)](/sssd.conf/5.md) for details.

If no Smartcard is available after the timeout or certificate based authentication is not allowed for the current service PAM\_AUTHINFO\_UNAVAIL is returned.

**allow\_chauthtok\_by\_root**

By default the chauthtok PAM action will short-circuit to returning PAM\_SUCCESS when pam\_sss.so is invoked by root user.

This option disables this behavior allowing to change auth tokens when running as root.

## MODULE TYPES PROVIDED

All module types (**account**, **auth**, **password** and **session**) are provided.

If SSSD's PAM responder is not running, e.g. if the PAM responder socket is not available, pam\_sss will return PAM\_USER\_UNKNOWN when called as **account** module to avoid issues with users from other sources during access control.

## RETURN VALUES

PAM\_SUCCESS

The PAM operation finished successfully.

PAM\_USER\_UNKNOWN

The user is not known to the authentication service or the SSSD's PAM responder is not running.

PAM\_AUTH\_ERR

Authentication failure. Also, could be returned when there is a problem with getting the certificate.

PAM\_PERM\_DENIED

Permission denied. The SSSD log files may contain additional information about the error.

PAM\_IGNORE

See options **ignore\_unknown\_user** and **ignore\_authinfo\_unavail**.

PAM\_AUTHTOK\_ERR

Unable to obtain the new authentication token. Also, could be returned when the user authenticates with certificates and multiple certificates are available, but the installed version of GDM does not support selection from multiple certificates.

PAM\_AUTHINFO\_UNAVAIL

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

PAM\_BUF\_ERR

A memory error occurred. Also, could be returned when options use\_first\_pass or use\_authtok were set, but no password was found from the previously stacked PAM module.

PAM\_SYSTEM\_ERR

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

PAM\_CRED\_ERR

Unable to set the credentials of the user.

PAM\_CRED\_INSUFFICIENT

The application does not have sufficient credentials to authenticate the user. For example, missing PIN during smartcard authentication or missing factor during two-factor authentication.

PAM\_SERVICE\_ERR

Error in service module.

PAM\_NEW\_AUTHTOK\_REQD

The user's authentication token has expired.

PAM\_ACCT\_EXPIRED

The user account has expired.

PAM\_SESSION\_ERR

Unable to fetch IPA Desktop Profile rules or user info.

PAM\_CRED\_UNAVAIL

Unable to retrieve Kerberos user credentials.

PAM\_NO\_MODULE\_DATA

No authentication method was found by Kerberos. This might happen if the user has a Smartcard assigned but the pkint plugin is not available on the client.

PAM\_CONV\_ERR

Conversation failure.

PAM\_AUTHTOK\_LOCK\_BUSY

No KDC suitable for password change is available.

PAM\_ABORT

Unknown PAM call.

PAM\_MODULE\_UNKNOWN

Unsupported PAM task or command.

PAM\_BAD\_ITEM

The authentication module cannot handle Smartcard credentials.

## FILES

If a password reset by root fails, because the corresponding SSSD provider does not support password resets, an individual message can be displayed. This message can e.g. contain instructions about how to reset a password.

The message is read from the file pam\_sss\_pw\_reset\_message.LOC where LOC stands for a locale string returned by [**setlocale**(3)](/setlocale/3.md). If there is no matching file the content of pam\_sss\_pw\_reset\_message.txt is displayed. Root must be the owner of the files and only root may have read and write permissions while all other users must have only read permissions.

These files are searched in the directory /etc/sssd/customize/DOMAIN\_NAME/. If no matching file is present a generic message is displayed.

## SEE ALSO

[**sssd**(8)](/sssd/8.md), [**sssd.conf**(5)](/sssd.conf/5.md), [**sssd-ldap**(5)](/sssd-ldap/5.md), [**sssd-ldap-attributes**(5)](/sssd-ldap-attributes/5.md), [**sssd-krb5**(5)](/sssd-krb5/5.md), [**sssd-simple**(5)](/sssd-simple/5.md), [**sssd-ipa**(5)](/sssd-ipa/5.md), [**sssd-ad**(5)](/sssd-ad/5.md), [**sssd-idp**(5)](/sssd-idp/5.md), [**sssd-sudo**(5)](/sssd-sudo/5.md), [**sssd-session-recording**(5)](/sssd-session-recording/5.md), [**sss\_cache**(8)](/sss_cache/8.md), [**sss\_debuglevel**(8)](/sss_debuglevel/8.md), [**sss\_obfuscate**(8)](/sss_obfuscate/8.md), [**sss\_seed**(8)](/sss_seed/8.md), [**sssd\_krb5\_locator\_plugin**(8)](/sssd_krb5_locator_plugin/8.md), [**sss\_ssh\_authorizedkeys**(1)](/sss_ssh_authorizedkeys/1.md), [**sss\_ssh\_knownhosts**(1)](/sss_ssh_knownhosts/1.md), [**sssd-ifp**(5)](/sssd-ifp/5.md), [**pam\_sss**(8)](/pam_sss/8.md). [**sss\_rpcidmapd**(5)](/sss_rpcidmapd/5.md)

## AUTHORS

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