6.2.3 Command Options for Connecting to the Server

This section describes options supported by most MySQL client programs that control how client programs establish connections to the server, whether connections are encrypted, and whether connections are compressed. These options can be given on the command line or in an option file.

• Command Options for Connection Establishment

• Command Options for Encrypted Connections

• Command Options for Connection Compression

Command Options for Connection Establishment

This section describes options that control how client programs establish connections to the server. For additional information and examples showing how to use them, see Section 6.2.4, “Connecting to the MySQL Server Using Command Options”.

Table 6.4 Connection-Establishment Option Summary

Option Name	Description
--default-auth	Authentication plugin to use
--host	Host on which MySQL server is located
--password	Password to use when connecting to server
--password1	First multifactor authentication password to use when connecting to server
--password2	Second multifactor authentication password to use when connecting to server
--password3	Third multifactor authentication password to use when connecting to server
--pipe	Connect to server using named pipe (Windows only)
--plugin-dir	Directory where plugins are installed
--port	TCP/IP port number for connection
--protocol	Transport protocol to use
--shared-memory-base-name	Shared-memory name for shared-memory connections (Windows only)
--socket	Unix socket file or Windows named pipe to use
--user	MySQL user name to use when connecting to server

• --default-auth=plugin

  Command-Line Format	--default-auth=plugin
  Type	String

  A hint about which client-side authentication plugin to use. See Section 8.2.17, “Pluggable Authentication”.

• --host=host_name, -h host_name

  Command-Line Format	--host=host_name
  Type	String
  Default Value	localhost

  The host on which the MySQL server is running. The value can be a host name, IPv4 address, or IPv6 address. The default value is localhost.

• --password[=pass_val], -p[pass_val]

  Command-Line Format	--password[=password]
  Type	String
  Default Value	[none]

  The password of the MySQL account used for connecting to the server. The password value is optional. If not given, the client program prompts for one. If given, there must be no space between --password= or -p and the password following it. If no password option is specified, the default is to send no password.

  Specifying a password on the command line should be considered insecure. To avoid giving the password on the command line, use an option file. See Section 8.1.2.1, “End-User Guidelines for Password Security”.

  To explicitly specify that there is no password and that the client program should not prompt for one, use the --skip-password option.

• --password1[=pass_val]

  Command-Line Format	--password1[=password]
  Type	String

  The password for multifactor authentication factor 1 of the MySQL account used for connecting to the server. The password value is optional. If not given, the client program prompts for one. If given, there must be no space between --password1= and the password following it. If no password option is specified, the default is to send no password.

  Specifying a password on the command line should be considered insecure. To avoid giving the password on the command line, use an option file. See Section 8.1.2.1, “End-User Guidelines for Password Security”.

  To explicitly specify that there is no password and that the client program should not prompt for one, use the --skip-password1 option.

  --password1 and --password are synonymous, as are --skip-password1 and --skip-password.

• --password2[=pass_val]

  Command-Line Format	--password2[=password]
  Type	String

  The password for multifactor authentication factor 2 of the MySQL account used for connecting to the server. The semantics of this option are similar to the semantics for --password1; see the description of that option for details.

• --password3[=pass_val]

  Command-Line Format	--password3[=password]
  Type	String

  The password for multifactor authentication factor 3 of the MySQL account used for connecting to the server. The semantics of this option are similar to the semantics for --password1; see the description of that option for details.

• --pipe, -W

  Command-Line Format	--pipe
  Type	String

  On Windows, connect to the server using a named pipe. This option applies only if the server was started with the named_pipe system variable enabled to support named-pipe connections. In addition, the user making the connection must be a member of the Windows group specified by the named_pipe_full_access_group system variable.

• --plugin-dir=dir_name

  Command-Line Format	--plugin-dir=dir_name
  Type	Directory name

  The directory in which to look for plugins. Specify this option if the --default-auth option is used to specify an authentication plugin but the client program does not find it. See Section 8.2.17, “Pluggable Authentication”.

• --port=port_num, -P port_num

  Command-Line Format	--port=port_num
  Type	Numeric
  Default Value	3306

  For TCP/IP connections, the port number to use. The default port number is 3306.

• --protocol={TCP|SOCKET|PIPE|MEMORY}

  Command-Line Format	--protocol=type
  Type	String
  Default Value	[see text]
  Valid Values	TCP SOCKET PIPE MEMORY

  This option explicitly specifies which transport protocol to use for connecting to the server. It is useful when other connection parameters normally result in use of a protocol other than the one you want. For example, connections on Unix to localhost are made using a Unix socket file by default:

  mysql --host=localhost

  To force TCP/IP transport to be used instead, specify a --protocol option:

  mysql --host=localhost --protocol=TCP

  The following table shows the permissible --protocol option values and indicates the applicable platforms for each value. The values are not case-sensitive.

  --protocol Value	Transport Protocol Used	Applicable Platforms
  TCP	TCP/IP transport to local or remote server	All
  SOCKET	Unix socket-file transport to local server	Unix and Unix-like systems
  PIPE	Named-pipe transport to local server	Windows
  MEMORY	Shared-memory transport to local server	Windows

  See also Section 6.2.7, “Connection Transport Protocols”

• --shared-memory-base-name=name

  Command-Line Format	--shared-memory-base-name=name
  Platform Specific	Windows

  On Windows, the shared-memory name to use for connections made using shared memory to a local server. The default value is MYSQL. The shared-memory name is case-sensitive.

  This option applies only if the server was started with the shared_memory system variable enabled to support shared-memory connections.

• --socket=path, -S path

  Command-Line Format	--socket={file_name|pipe_name}
  Type	String

  On Unix, the name of the Unix socket file to use for connections made using a named pipe to a local server. The default Unix socket file name is /tmp/mysql.sock.

  On Windows, the name of the named pipe to use for connections to a local server. The default Windows pipe name is MySQL. The pipe name is not case-sensitive.

  On Windows, this option applies only if the server was started with the named_pipe system variable enabled to support named-pipe connections. In addition, the user making the connection must be a member of the Windows group specified by the named_pipe_full_access_group system variable.

• --user=user_name, -u user_name

  Command-Line Format	--user=user_name
  Type	String

  The user name of the MySQL account to use for connecting to the server. The default user name is ODBC on Windows or your Unix login name on Unix.

Command Options for Encrypted Connections

This section describes options for client programs that specify whether to use encrypted connections to the server, the names of certificate and key files, and other parameters related to encrypted-connection support. For examples of suggested use and how to check whether a connection is encrypted, see Section 8.3.1, “Configuring MySQL to Use Encrypted Connections”.

Note

These options have an effect only for connections that use a transport protocol subject to encryption; that is, TCP/IP and Unix socket-file connections. See Section 6.2.7, “Connection Transport Protocols”

For information about using encrypted connections from the MySQL C API, see Support for Encrypted Connections.

Table 6.5 Connection-Encryption Option Summary

Option Name	Description
--get-server-public-key	Request RSA public key from server
--server-public-key-path	Path name to file containing RSA public key
--ssl-ca	File that contains list of trusted SSL Certificate Authorities
--ssl-capath	Directory that contains trusted SSL Certificate Authority certificate files
--ssl-cert	File that contains X.509 certificate
--ssl-cipher	Permissible ciphers for connection encryption
--ssl-crl	File that contains certificate revocation lists
--ssl-crlpath	Directory that contains certificate revocation-list files
--ssl-fips-mode	Whether to enable FIPS mode on client side
--ssl-key	File that contains X.509 key
--ssl-mode	Desired security state of connection to server
--ssl-session-data	File that contains SSL session data
--ssl-session-data-continue-on-failed-reuse	Whether to establish connections if session reuse fails
--tls-ciphersuites	Permissible TLSv1.3 ciphersuites for encrypted connections
--tls-version	Permissible TLS protocols for encrypted connections

• --get-server-public-key

  Command-Line Format	--get-server-public-key
  Type	Boolean

  Request from the server the public key required for RSA key pair-based password exchange. This option applies to clients that authenticate with the caching_sha2_password authentication plugin. For that plugin, the server does not send the public key unless requested. This option is ignored for accounts that do not authenticate with that plugin. It is also ignored if RSA-based password exchange is not used, as is the case when the client connects to the server using a secure connection.

  If --server-public-key-path=file_name is given and specifies a valid public key file, it takes precedence over --get-server-public-key.

  For information about the caching_sha2_password plugin, see Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication”.

• --server-public-key-path=file_name

  Command-Line Format	--server-public-key-path=file_name
  Type	File name

  The path name to a file in PEM format containing a client-side copy of the public key required by the server for RSA key pair-based password exchange. This option applies to clients that authenticate with the sha256_password (deprecated) or caching_sha2_password authentication plugin. This option is ignored for accounts that do not authenticate with one of those plugins. It is also ignored if RSA-based password exchange is not used, as is the case when the client connects to the server using a secure connection.

  If --server-public-key-path=file_name is given and specifies a valid public key file, it takes precedence over --get-server-public-key.

  This option is available only if MySQL was built using OpenSSL.

  For information about the sha256_password (deprecated) and caching_sha2_password plugins, see Section 8.4.1.3, “SHA-256 Pluggable Authentication”, and Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication”.

• --ssl-ca=file_name

  Command-Line Format	--ssl-ca=file_name
  Type	File name

  The path name of the Certificate Authority (CA) certificate file in PEM format. The file contains a list of trusted SSL Certificate Authorities.

  To tell the client not to authenticate the server certificate when establishing an encrypted connection to the server, specify neither --ssl-ca nor --ssl-capath. The server still verifies the client according to any applicable requirements established for the client account, and it still uses any ssl_ca or ssl_capath system variable values specified on the server side.

  To specify the CA file for the server, set the ssl_ca system variable.

• --ssl-capath=dir_name

  Command-Line Format	--ssl-capath=dir_name
  Type	Directory name

  The path name of the directory that contains trusted SSL certificate authority (CA) certificate files in PEM format.

  To tell the client not to authenticate the server certificate when establishing an encrypted connection to the server, specify neither --ssl-ca nor --ssl-capath. The server still verifies the client according to any applicable requirements established for the client account, and it still uses any ssl_ca or ssl_capath system variable values specified on the server side.

  To specify the CA directory for the server, set the ssl_capath system variable.

• --ssl-cert=file_name

  Command-Line Format	--ssl-cert=file_name
  Type	File name

  The path name of the client SSL public key certificate file in PEM format. Chained SSL certificates are supported.

  To specify the server SSL public key certificate file, set the ssl_cert system variable.

• --ssl-cipher=cipher_list

  Command-Line Format	--ssl-cipher=name
  Type	String

  The list of permissible encryption ciphers for connections that use TLSv1.2. If no cipher in the list is supported, encrypted connections that use these TLS protocols do not work.

  For greatest portability, cipher_list should be a list of one or more cipher names, separated by colons. Examples:

  --ssl-cipher=AES128-SHA
  --ssl-cipher=DHE-RSA-AES128-GCM-SHA256:AES128-SHA

  OpenSSL supports the syntax for specifying ciphers described in the OpenSSL documentation at https://www.openssl.org/docs/manmaster/man1/ciphers.html.

  For information about which encryption ciphers MySQL supports, see Section 8.3.2, “Encrypted Connection TLS Protocols and Ciphers”.

  To specify the encryption ciphers for the server, set the ssl_cipher system variable.

• --ssl-crl=file_name

  Command-Line Format	--ssl-crl=file_name
  Type	File name

  The path name of the file containing certificate revocation lists in PEM format.

  If neither --ssl-crl nor --ssl-crlpath is given, no CRL checks are performed, even if the CA path contains certificate revocation lists.

  To specify the revocation-list file for the server, set the ssl_crl system variable.

• --ssl-crlpath=dir_name

  Command-Line Format	--ssl-crlpath=dir_name
  Type	Directory name

  The path name of the directory that contains certificate revocation-list files in PEM format.

  If neither --ssl-crl nor --ssl-crlpath is given, no CRL checks are performed, even if the CA path contains certificate revocation lists.

  To specify the revocation-list directory for the server, set the ssl_crlpath system variable.

• --ssl-fips-mode={OFF|ON|STRICT}

  Command-Line Format	--ssl-fips-mode={OFF|ON|STRICT}
  Deprecated	Yes
  Type	Enumeration
  Default Value	OFF
  Valid Values	OFF ON STRICT

  Controls whether to enable FIPS mode on the client side. The --ssl-fips-mode option differs from other --ssl-xxx options in that it is not used to establish encrypted connections, but rather to affect which cryptographic operations to permit. See Section 8.8, “FIPS Support”.

  These --ssl-fips-mode values are permissible:

  • OFF: Disable FIPS mode.

  • ON: Enable FIPS mode.

  • STRICT: Enable “strict” FIPS mode.

  Note

  If the OpenSSL FIPS Object Module is not available, the only permissible value for --ssl-fips-mode is OFF. In this case, setting --ssl-fips-mode to ON or STRICT causes the client to produce a warning at startup and to operate in non-FIPS mode.

  To specify the FIPS mode for the server, set the ssl_fips_mode system variable.

• --ssl-key=file_name

  Command-Line Format	--ssl-key=file_name
  Type	File name

  The path name of the client SSL private key file in PEM format. For better security, use a certificate with an RSA key size of at least 2048 bits.

  If the key file is protected by a passphrase, the client program prompts the user for the passphrase. The password must be given interactively; it cannot be stored in a file. If the passphrase is incorrect, the program continues as if it could not read the key.

  To specify the server SSL private key file, set the ssl_key system variable.

• --ssl-mode=mode

  Command-Line Format	--ssl-mode=mode
  Type	Enumeration
  Default Value	PREFERRED
  Valid Values	DISABLED PREFERRED REQUIRED VERIFY_CA VERIFY_IDENTITY

  This option specifies the desired security state of the connection to the server. These mode values are permissible, in order of increasing strictness:

  • DISABLED: Establish an unencrypted connection.

  • PREFERRED: Establish an encrypted connection if the server supports encrypted connections, falling back to an unencrypted connection if an encrypted connection cannot be established. This is the default if --ssl-mode is not specified.

    Connections over Unix socket files are not encrypted with a mode of PREFERRED. To enforce encryption for Unix socket-file connections, use a mode of REQUIRED or stricter. (However, socket-file transport is secure by default, so encrypting a socket-file connection makes it no more secure and increases CPU load.)

  • REQUIRED: Establish an encrypted connection if the server supports encrypted connections. The connection attempt fails if an encrypted connection cannot be established.

  • VERIFY_CA: Like REQUIRED, but additionally verify the server Certificate Authority (CA) certificate against the configured CA certificates. The connection attempt fails if no valid matching CA certificates are found.

  • VERIFY_IDENTITY: Like VERIFY_CA, but additionally perform host name identity verification by checking the host name the client uses for connecting to the server against the identity in the certificate that the server sends to the client:

    • If the client uses OpenSSL 1.0.2 or higher, the client checks whether the host name that it uses for connecting matches either the Subject Alternative Name value or the Common Name value in the server certificate. Host name identity verification also works with certificates that specify the Common Name using wildcards.

    • Otherwise, the client checks whether the host name that it uses for connecting matches the Common Name value in the server certificate.

    The connection fails if there is a mismatch. For encrypted connections, this option helps prevent man-in-the-middle attacks.

    Note

    Host name identity verification with VERIFY_IDENTITY does not work with self-signed certificates that are created automatically by the server (see Section 8.3.3.1, “Creating SSL and RSA Certificates and Keys using MySQL”). Such self-signed certificates do not contain the server name as the Common Name value.

  Important

  The default setting, --ssl-mode=PREFERRED, produces an encrypted connection if the other default settings are unchanged. However, to help prevent sophisticated man-in-the-middle attacks, it is important for the client to verify the server’s identity. The settings --ssl-mode=VERIFY_CA and --ssl-mode=VERIFY_IDENTITY are a better choice than the default setting to help prevent this type of attack. To implement one of these settings, you must first ensure that the CA certificate for the server is reliably available to all the clients that use it in your environment, otherwise availability issues will result. For this reason, they are not the default setting.

  The --ssl-mode option interacts with CA certificate options as follows:

  • If --ssl-mode is not explicitly set otherwise, use of --ssl-ca or --ssl-capath implies --ssl-mode=VERIFY_CA.

  • For --ssl-mode values of VERIFY_CA or VERIFY_IDENTITY, --ssl-ca or --ssl-capath is also required, to supply a CA certificate that matches the one used by the server.

  • An explicit --ssl-mode option with a value other than VERIFY_CA or VERIFY_IDENTITY, together with an explicit --ssl-ca or --ssl-capath option, produces a warning that no verification of the server certificate is performed, despite a CA certificate option being specified.

  To require use of encrypted connections by a MySQL account, use CREATE USER to create the account with a REQUIRE SSL clause, or use ALTER USER for an existing account to add a REQUIRE SSL clause. This causes connection attempts by clients that use the account to be rejected unless MySQL supports encrypted connections and an encrypted connection can be established.

  The REQUIRE clause permits other encryption-related options, which can be used to enforce security requirements stricter than REQUIRE SSL. For additional details about which command options may or must be specified by clients that connect using accounts configured using the various REQUIRE options, see CREATE USER SSL/TLS Options.

• --ssl-session-data=file_name

  Command-Line Format	--ssl-session-data=file_name
  Type	File name

  The path name of the client SSL session data file in PEM format for session reuse.

  When you invoke a MySQL client program with the --ssl-session-data option, the client attempts to deserialize session data from the file, if provided, and then use it to establish a new connection. If you supply a file, but the session is not reused, then the connection fails unless you also specified the --ssl-session-data-continue-on-failed-reuse option on the command line when you invoked the client program.

  The mysql command, ssl_session_data_print, generates the session data file (see Section 6.5.1.2, “mysql Client Commands”).

• ssl-session-data-continue-on-failed-reuse

  Command-Line Format	--ssl-session-data-continue-on-failed-reuse
  Type	Boolean
  Default Value	OFF

  Controls whether a new connection is started to replace an attempted connection that tried but failed to reuse session data specified with the --ssl-session-data command-line option. By default, the --ssl-session-data-continue-on-failed-reuse command-line option is off, which causes a client program to return a connect failure when session data are supplied and not reused.

  To ensure that a new, unrelated connection opens after session reuse fails silently, invoke MySQL client programs with both the --ssl-session-data and --ssl-session-data-continue-on-failed-reuse command-line options.

• --tls-ciphersuites=ciphersuite_list

  Command-Line Format	--tls-ciphersuites=ciphersuite_list
  Type	String
  Default Value	empty string

  This option specifies which ciphersuites the client permits for encrypted connections that use TLSv1.3. The value is a list of zero or more colon-separated ciphersuite names. For example:

  mysql --tls-ciphersuites="suite1:suite2:suite3"

  The ciphersuites that can be named for this option depend on the SSL library used to compile MySQL. If this option is not set, the client permits the default set of ciphersuites. If the option is set to the empty string, no ciphersuites are enabled and encrypted connections cannot be established. For more information, see Section 8.3.2, “Encrypted Connection TLS Protocols and Ciphers”.

  To specify which ciphersuites the server permits, set the tls_ciphersuites system variable.

• --tls-version=protocol_list

  Command-Line Format	--tls-version=protocol_list
  Type	String
  Default Value	TLSv1,TLSv1.1,TLSv1.2,TLSv1.3 (OpenSSL 1.1.1 or higher) TLSv1,TLSv1.1,TLSv1.2 (otherwise)

  This option specifies the TLS protocols the client permits for encrypted connections. The value is a list of one or more comma-separated protocol versions. For example:

  mysql --tls-version="TLSv1.2,TLSv1.3"

  The protocols that can be named for this option depend on the SSL library used to compile MySQL, and on the MySQL Server release.

  Important

  • Clients, including MySQL Shell, that support the --tls-version option cannot make a TLS/SSL connection with the protocol set to TLSv1 or TLSv1.1. If a client attempts to connect using these protocols, for TCP connections, the connection fails, and an error is returned to the client. For socket connections, if --ssl-mode is set to REQUIRED, the connection fails, otherwise the connection is made but with TLS/SSL disabled. See Removal of Support for the TLSv1 and TLSv1.1 Protocols for more information.

  • Support for the TLSv1.3 protocol is available in MySQL Server, provided that MySQL Server was compiled using OpenSSL 1.1.1 or higher. The server checks the version of OpenSSL at startup, and if it is lower than 1.1.1, TLSv1.3 is removed from the default value for the server system variables relating to the TLS version (such as the tls_version system variable).

  Permitted protocols should be chosen such as not to leave “holes” in the list. For example, these values do not have holes:

  --tls-version="TLSv1.2,TLSv1.3"
  --tls-version="TLSv1.3"

  For details, see Section 8.3.2, “Encrypted Connection TLS Protocols and Ciphers”.

  To specify which TLS protocols the server permits, set the tls_version system variable.

Command Options for Connection Compression

This section describes options that enable client programs to control use of compression for connections to the server. For additional information and examples showing how to use them, see Section 6.2.8, “Connection Compression Control”.

Table 6.6 Connection-Compression Option Summary

Option Name	Description
--compress	Compress all information sent between client and server
--compression-algorithms	Permitted compression algorithms for connections to server
--zstd-compression-level	Compression level for connections to server that use zstd compression

• --compress, -C

  Command-Line Format	--compress[={OFF|ON}]
  Deprecated	Yes
  Type	Boolean
  Default Value	OFF

  Compress all information sent between the client and the server if possible.

  This option is deprecated. Expect it to be removed in a future version of MySQL. See Configuring Legacy Connection Compression.

• --compression-algorithms=value

  Command-Line Format	--compression-algorithms=value
  Type	Set
  Default Value	uncompressed
  Valid Values	zlib zstd uncompressed

  The permitted compression algorithms for connections to the server. The available algorithms are the same as for the protocol_compression_algorithms system variable. The default value is uncompressed.

• --zstd-compression-level=level

  Command-Line Format	--zstd-compression-level=#
  Type	Integer

  The compression level to use for connections to the server that use the zstd compression algorithm. The permitted levels are from 1 to 22, with larger values indicating increasing levels of compression. The default zstd compression level is 3. The compression level setting has no effect on connections that do not use zstd compression.