As mentioned in Connection Volume Management, to allow for the need to perform administrative operations even when max_connections  connections are already established on the interfaces used for ordinary connections, the MySQL server permits a single administrative connection to users who have the CONNECTION_ADMIN  privilege (or the deprecated SUPER  privilege). 

Additionally, as of MySQL 8.0.14, the server permits dedicating a TCP/IP port for administrative connections, as described in the following sections. 

## Administrative Interface Characteristics 

•Administrative Interface Characteristics 

•Administrative Interface Support for Encrypted Connections 

The administrative connection interface has these characteristics: 

•The server enables the interface only if the admin_address  system variable is set at startup to indicate the IP address for it. If admin_address  is not set, the server maintains no administrative interface. 

•The admin_port  system variable specifies the interface TCP/IP port number (default 33062). 

•There is no limit on the number of administrative connections, but connections are permitted only for users who have the SERVICE_CONNECTION_ADMIN  privilege. 

•The create_admin_listener_thread  system variable enables DBAs to choose at startup whether the administrative interface has its own separate thread. The default is OFF ; that is, the manager thread for ordinary connections on the main interface also handles connections for the administrative interface. 

These lines in the server my.cnf  file enable the administrative interface on the loopback interface and configure it to use port number 33064 (that is, a port different from the default): 

[mysqld] admin_address=127.0.0.1 admin_port=33064 

MySQL client programs connect to either the main or administrative interface by specifying appropriate connection parameters. If the server running on the local host is using the default TCP/IP port numbers of 3306 and 33062 for the main and administrative interfaces, these commands connect to those interfaces: 

## Administrative Interface Support for Encrypted Connections 

mysql --protocol=TCP --port=3306 mysql --protocol=TCP --port=33062 

Prior to MySQL 8.0.21, the administrative interface supports encrypted connections using the connection- encryption configuration that applies to the main interface. As of MySQL 8.0.21, the administrative interface has its own configuration parameters for encrypted connections. These correspond to the main interface parameters but enable independent configuration of encrypted connections for the administrative interface: 

•The admin_tls_ xxx  and admin_ssl_ xxx  system variables are like the tls_ xxx  and ssl_ xxx system variables, but they configure the TLS context for the administrative interface rather than the main interface. 

•The --admin-ssl  option is like the --ssl  option, but it enables or disables support for encrypted connections on the administrative interface rather than the main interface. 

Because support for encrypted connections is enabled by default, it is normally unnecessary to specify --admin-ssl . As of MySQL 8.0.26, --admin-ssl  is deprecated and subject to removal in a future MySQL version. 

