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MySQL 8.0 Reference Manual  /  ...  /  Encrypted Connection Protocols and Ciphers

6.3.5 Encrypted Connection Protocols and Ciphers

To determine which encryption protocol and cipher are in use for an encrypted connection, use the following statements to check the values of the Ssl_version and Ssl_cipher status variables:

mysql> SHOW SESSION STATUS LIKE 'Ssl_version';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Ssl_version   | TLSv1 |
+---------------+-------+
mysql> SHOW SESSION STATUS LIKE 'Ssl_cipher';
+---------------+---------------------------+
| Variable_name | Value                     |
+---------------+---------------------------+
| Ssl_cipher    | DHE-RSA-AES128-GCM-SHA256 |
+---------------+---------------------------+

If the connection is not encrypted, both variables have an empty value.

MySQL supports encrypted connections using the TLSv1, TLSv1.1, TLSv1.2, and TLSv1.3 protocols.

Note

Support for the TLSv1.3 protocol is available as of MySQL 8.0.16, but requires compiling MySQL using OpenSSL 1.1.1 or higher. If the SSL library does not support TLSv1.3, neither does MySQL and the TLSv1.3-related parts of the following discussion do not apply.

Currently, Group Replication does not support TLSv1.3.

The value of the tls_version system variable determines which protocols a server permits for encrypted connections. The tls_version value applies to connections from clients and from slave servers using regular master/slave replication. The variable value is a list of one or more comma-separated protocol names from this list (not case-sensitive): TLSv1, TLSv1.1, TLSv1.2, and (if available) TLSV1.3. By default, this variable lists all protocols supported by the SSL library used to compile MySQL. To determine the value of tls_version at runtime, use this statement:

mysql> SHOW GLOBAL VARIABLES LIKE 'tls_version';
+---------------+-----------------------+
| Variable_name | Value                 |
+---------------+-----------------------+
| tls_version   | TLSv1,TLSv1.1,TLSv1.2 |
+---------------+-----------------------+

To change the value of tls_version, set it at server startup. For example, to permit connections that use the TLSv1.1 or TLSv1.2 protocol, but prohibit connections that use the less-secure TLSv1 protocol, use these lines in the server my.cnf file:

[mysqld]
tls_version=TLSv1.1,TLSv1.2

To be even more restrictive and permit only TLSv1.2 connections, set tls_version like this:

[mysqld]
tls_version=TLSv1.2

As of MySQL 8.0.16, tls_version can also be changed at runtime. See Server-Side Runtime Configuration for Encrypted Connections.

For client programs, the --tls-version option specifies which TLS protocols a client permits for connections to the server. The format of the option value is the same as for the tls_version system variable.

For regular replication, the MASTER_TLS_VERSION option for the CHANGE MASTER TO statement specifies which TLS protocols a slave server permits for connections to the master. The format of the option value is the same as for the tls_version system variable. See Section 17.3.9, “Setting Up Replication to Use Encrypted Connections”.

The protocols that can be specified for MASTER_TLS_VERSION depend only on the SSL library. This option is independent of and not affected by the tls_version value configured on the slave server. For example, a server that acts as a replication slave can be configured with tls_version set to TLSv1.3 to permit only incoming connections that use TLSv1.3, but also configured with MASTER_TLS_VERSION set to TLSv1.2 to connect as a slave only to masters that permit TLSv1.2.

By default, MySQL attempts to use the highest TLS protocol version available, depending on the SSL library used to compile the server and client, which key size is used, and whether the server or client are restricted from using some protocols (for example, by means of tls_version/--tls-version):

  • If TLSv1.3 is available, it is used if possible. If not, MySQL continues through the list of available protocols, using TLSv1.2 if possible, and so forth.

  • TLSv1.2 does not work with all ciphers that have a key size of 512 bits or less. To use this protocol with such a key, use --ssl-cipher to specify the cipher name explicitly:

    AES128-SHA
    AES128-SHA256
    AES256-SHA
    AES256-SHA256
    CAMELLIA128-SHA
    CAMELLIA256-SHA
    DES-CBC3-SHA
    DHE-RSA-AES256-SHA
    RC4-MD5
    RC4-SHA
    SEED-SHA
  • For better security, use a certificate with an RSA key size of at least 2048 bits.

If the server and client protocol capabilities have no protocol in common, the server terminates the connection request. Examples:

  • if the server is configured with tls_version=TLSv1.1,TLSv1.2, connection attempts fail for clients invoked with --tls-version=TLSv1, and for older clients that do not support the --tls-version option and implicitly support only TLSv1.

  • Similarly, connection attempts fail for replication slaves configured with MASTER_TLS_VERSION = 'TLSv1', and for older slaves that do not support the MASTER_TLS_VERSION option and implicitly support only TLSv1.

OpenSSL 1.1.1 and higher supports the following ciphersuites, the first three of which are enabled by default:

TLS_AES_128_GCM_SHA256
TLS_AES_256_GCM_SHA384
TLS_CHACHA20_POLY1305_SHA256
TLS_AES_128_CCM_SHA256
TLS_AES_128_CCM_8_SHA256

To configure the permitted TLSv1.3 ciphersuites explicitly:

In each case, the configuration value is a list of one or more colon-separated ciphersuite names.

MySQL permits specifying a list of protocols to support. This list is passed directly down to the underlying SSL library and is ultimately up to that library what protocols it actually enables from the supplied list. Please refer to the MySQL source code and the OpenSSL SSL_CTX_new() documentation for information about how the SSL library handles this.

To determine which ciphers a given server supports, use the following statement to check the value of the Ssl_cipher_list status variable:

SHOW SESSION STATUS LIKE 'Ssl_cipher_list';

The Ssl_cipher_list status variable lists the possible SSL ciphers (empty for non-SSL connections). If MySQL supports TLSv1.3, the value includes the possible TLSv1.3 ciphersuites.

Order of ciphers passed by MySQL to the SSL library is significant. More secure ciphers are mentioned first in the list, and the first cipher supported by the provided certificate is selected.

MySQL passes this cipher list to the SSL library:

ECDHE-ECDSA-AES128-GCM-SHA256
ECDHE-ECDSA-AES256-GCM-SHA384
ECDHE-RSA-AES128-GCM-SHA256
ECDHE-RSA-AES256-GCM-SHA384
ECDHE-ECDSA-AES128-SHA256
ECDHE-RSA-AES128-SHA256
ECDHE-ECDSA-AES256-SHA384
ECDHE-RSA-AES256-SHA384
DHE-RSA-AES128-GCM-SHA256
DHE-DSS-AES128-GCM-SHA256
DHE-RSA-AES128-SHA256
DHE-DSS-AES128-SHA256
DHE-DSS-AES256-GCM-SHA384
DHE-RSA-AES256-SHA256
DHE-DSS-AES256-SHA256
ECDHE-RSA-AES128-SHA
ECDHE-ECDSA-AES128-SHA
ECDHE-RSA-AES256-SHA
ECDHE-ECDSA-AES256-SHA
DHE-DSS-AES128-SHA
DHE-RSA-AES128-SHA
TLS_DHE_DSS_WITH_AES_256_CBC_SHA
DHE-RSA-AES256-SHA
AES128-GCM-SHA256
DH-DSS-AES128-GCM-SHA256
ECDH-ECDSA-AES128-GCM-SHA256
AES256-GCM-SHA384
DH-DSS-AES256-GCM-SHA384
ECDH-ECDSA-AES256-GCM-SHA384
AES128-SHA256
DH-DSS-AES128-SHA256
ECDH-ECDSA-AES128-SHA256
AES256-SHA256
DH-DSS-AES256-SHA256
ECDH-ECDSA-AES256-SHA384
AES128-SHA
DH-DSS-AES128-SHA
ECDH-ECDSA-AES128-SHA
AES256-SHA
DH-DSS-AES256-SHA
ECDH-ECDSA-AES256-SHA
DHE-RSA-AES256-GCM-SHA384
DH-RSA-AES128-GCM-SHA256
ECDH-RSA-AES128-GCM-SHA256
DH-RSA-AES256-GCM-SHA384
ECDH-RSA-AES256-GCM-SHA384
DH-RSA-AES128-SHA256
ECDH-RSA-AES128-SHA256
DH-RSA-AES256-SHA256
ECDH-RSA-AES256-SHA384
ECDHE-RSA-AES128-SHA
ECDHE-ECDSA-AES128-SHA
ECDHE-RSA-AES256-SHA
ECDHE-ECDSA-AES256-SHA
DHE-DSS-AES128-SHA
DHE-RSA-AES128-SHA
TLS_DHE_DSS_WITH_AES_256_CBC_SHA
DHE-RSA-AES256-SHA
AES128-SHA
DH-DSS-AES128-SHA
ECDH-ECDSA-AES128-SHA
AES256-SHA
DH-DSS-AES256-SHA
ECDH-ECDSA-AES256-SHA
DH-RSA-AES128-SHA
ECDH-RSA-AES128-SHA
DH-RSA-AES256-SHA
ECDH-RSA-AES256-SHA
DES-CBC3-SHA

These cipher restrictions are in place:

  • The following ciphers are permanently restricted:

    !DHE-DSS-DES-CBC3-SHA
    !DHE-RSA-DES-CBC3-SHA
    !ECDH-RSA-DES-CBC3-SHA
    !ECDH-ECDSA-DES-CBC3-SHA
    !ECDHE-RSA-DES-CBC3-SHA
    !ECDHE-ECDSA-DES-CBC3-SHA
  • The following categories of ciphers are permanently restricted:

    !aNULL
    !eNULL
    !EXPORT
    !LOW
    !MD5
    !DES
    !RC2
    !RC4
    !PSK
    !SSLv3

If the server is started using a compatible certificate that uses any of the preceding restricted ciphers or cipher categories, the server starts with support for encrypted connections disabled.