.. _authentication-nss: ===== NSS ===== .. deprecated:: v2.3.0 .. NOTE:: This userdb is probably useless with Dovecot v2.0.12+, since it uses ``getpwnam_r()``, which supports error reporting. Usually `NSS `_ is used with :ref:`authentication-passwd` userdb, but it has one problem: * It can't distinguish between temporary and permanent errors. So if you're using e.g. ``nss_ldap`` and your LDAP database is down, all userdb lookups may return ``user doesn't exist`` errors. This is especially bad if you're using :ref:`lda`, which causes the mails to be bounced back to sender. The NSS userdb works around this problem by loading the NSS modules and calling them itself. This is a bit kludgy, and it probably works only with Linux. This userdb has two parameters: * **service=**: This parameter is required. The name specifies what NSS module to use, for example ``ldap``. * **blocking=no** causes the lookups to be done in auth master processes instead of in worker processes. Example ======= .. code-block:: none userdb { driver = nss args = service=ldap }