Access denied when connecting to mongosqld with MySQL
As per MongoDB documentation Connect from the MySQL Client You can use the command-line MySQL client to connect to the MongoDB Connector for BI.

Connect from MySQL without Authentication or TLS/SSL

To connect to a mongosqld instance listening on the MySQL default port 3307, run the following command:

mysql --protocol tcp --port 3307


Connect from MySQL with Authentication

Install the C Authentication Plugin as described in Install the C Authentication Plugin.

The following example uses the C authentication plugin to connect to a mongosqld instance listening on port 3307 as user reportsUser. The MySQL shell prompts for the password after the command has been entered.

mysql --user='reportsUser?source=admin' --default-auth=mongosql_auth -p


Note: This example assumes that the authentication plugin file mongosql_auth.so is located in the default MySQL plugin folder. The location of the plugin folder varies by platform, but you can locate it by running the following command:

mysql_config --plugindir


mysql_config.pl can find the plugin directory only on macOS and Linux hosts.

Important : The C Authentication plugin was developed against MySQL 5.7.18 Community Edition (64-bit), and tested with MySQL 5.7.18 Community Edition and the latest version of MongoDB Connector for BI. The plugin is not compatible with MySQL Server or Connector/ODBC driver version 8 and later.

Connect from MySQL with Authentication and TLS/SSL

To connect to a mongosqld instance listening on port 3307, as user grace using authentication mechanism PLAIN, and using specific TLS/SSL CA and x.509 certificates, run the following command:

mysql --enable-cleartext-plugin --protocol tcp --port 3307 \
  --user='grace?mechanism=PLAIN&amp;source=$external' \
  --ssl-ca=/path_to_the_CAcert/ca.crt \
  --ssl-key=/path_to_my_certificate_key/mysql.key \
  --ssl-cert=/path_to_my_client_certificate/mysql.crt \
  -p


Important: The binary distribution of MySQL Community uses the yaSSL SSL library to encrypt connections. MySQL Enterprise uses OpenSSL which is compatible with MongoDB Connector for BI. Use MySQL Enterprise to connect to BI Connector over TLS / SSL.

If using the $external authentication source, wrap your username in single quotes or escape the $ character with a backslash to prevent your shell from performing interpolation.

For further your reference here