Authentication Plugins The following table shows the plugin and library file names. The file name suffix might differ on your system. The file must be located in the directory named by the  plugin_dir  system variable. For installation information, see Installing PAM Pluggable Authentication. Table 6.16 Plugin and Library Names for PAM Authentication Plugin or File Plugin or File Name Server-side plugin authentication_pam Client-side plugin mysql_clear_password Library file authentication_pam.so The client-side  mysql_clear_password  cleartext plugin that communicates with the server-side PAM plugin is built into the  libmysqlclient  client library and is included in all distributions, including community distributions. Inclusion of the client-side cleartext plugin in all MySQL distributions enables clients from any distribution to connect to a server that has the server-side PAM plugin loaded. The following sections provide installation and usage information specific to PAM pluggable authentication: •Installing PAM Pluggable Authentication •How PAM Authentication of MySQL Users Works •Uninstalling PAM Pluggable Authentication •Using PAM Pluggable Authentication •PAM Unix Password Authentication without Proxy Users •PAM LDAP Authentication without Proxy Users •PAM Unix Password Authentication with Proxy Users and Group Mapping •PAM Authentication Access to Unix Password Store •PAM Authentication Debugging How PAM Authentication of MySQL Users Works For general information about pluggable authentication in MySQL, see Section 6.2.17, “Pluggable Authentication” . For information about the  mysql_clear_password  plugin, see Section 6.4.1.4, “Client- Side Cleartext Pluggable Authentication” . For proxy user information, see Section 6.2.18, “Proxy Users” . This section provides a general overview of how MySQL and PAM work together to authenticate MySQL users. For examples showing how to set up MySQL accounts to use specific PAM services, see Using PAM Pluggable Authentication. 1. The client program and the server communicate, with the client sending to the server the client user name (the operating system user name by default) and password: •The client user name is the external user name. •For accounts that use the PAM server-side authentication plugin, the corresponding client-side plugin is  mysql_clear_password . This client-side plugin performs no password hashing, with the result that the client sends the password to the server as cleartext. 2. The server finds a matching MySQL account based on the external user name and the host from which the client connects. The PAM plugin uses the information passed to it by MySQL Server (such as 1318