This is nss-pam-ldapd which provides a Name Service Switch (NSS, nsswitch) module that allows your LDAP server to provide user account, group, host name, alias, netgroup, and basically any other information that you would normally get from /etc flat files or NIS. It also provides a Pluggable Authentication Module (PAM) to do identity and authentication management with an LDAP server on unix systems.
This is implemented using thin NSS and PAM modules which delegate to a dedicated service (nslcd) that queries the LDAP server with persistent connections, authentication, attribute translation, etc.
The NSS module was originally a fork of nss_ldap with some structural design improvements. The most important features of nss-pam-ldapd are:
See the documentation section for more details.