Pluggable Authentication elsewhere than in the  mysql.user  system table. For example, plugins can be created to use external authentication methods such as PAM, Windows login IDs, LDAP, or Kerberos. If you start the server with the  --skip-grant-tables  option, authentication plugins are not used even if loaded because the server performs no client authentication and permits any client to connect. Because this is insecure, if the server is started with the  --skip-grant-tables  option, it also disables remote connections by enabling  skip_networking . MySQL 8.0 provides these authentication plugins: •Plugins that perform authentication using LDAP (Lightweight Directory Access Protocol) to authenticate MySQL users by accessing directory services such as X.500. These plugins support proxy users as well. See Section 6.4.1.7, “LDAP Pluggable Authentication” . •A plugin that performs external authentication on Windows, enabling MySQL Server to use native Windows services to authenticate client connections. Users who have logged in to Windows can connect from MySQL client programs to the server based on the information in their environment without specifying an additional password. This plugin supports proxy users as well. See Section 6.4.1.6, “Windows Pluggable Authentication” . •A plugin that performs external authentication using PAM (Pluggable Authentication Modules), enabling MySQL Server to use PAM to authenticate MySQL users. This plugin supports proxy users as well. See Section 6.4.1.5, “PAM Pluggable Authentication” . •A client-side plugin that sends the password to the server without hashing or encryption. This plugin is used in conjunction with server-side plugins that require access to the password exactly as provided by the client user. See Section 6.4.1.4, “Client-Side Cleartext Pluggable Authentication” . •Plugins that perform authentication using SHA-256 password hashing. This is stronger encryption than that available with native authentication. See Section 6.4.1.2, “Caching SHA-2 Pluggable Authentication” , and Section 6.4.1.3, “SHA-256 Pluggable Authentication” . •A plugin that performs native authentication; that is, authentication based on the password hashing method in use from before the introduction of pluggable authentication in MySQL. The mysql_native_password  plugin implements authentication based on this native password hashing method. See Section 6.4.1.1, “Native Pluggable Authentication” . •Available Authentication Plugins •Authentication Plugin Usage •Authentication Plugin Client/Server Compatibility •Authentication Plugin Connector-Writing Considerations •Restrictions on Pluggable Authentication • Proxy users:   If a user is permitted to connect, an authentication plugin can return to the server a user name different from the name of the connecting user, to indicate that the connecting user is a proxy for another user (the proxied user). While the connection lasts, the proxy user is treated, for purposes of access control, as having the privileges of the proxied user. In effect, one user impersonates another. For more information, see Section 6.2.18, “Proxy Users” . Note Available Authentication Plugins 1259