16.3.8 Setting Up Replication to Use Encrypted Connections
To use an encrypted connection for the transfer of the binary log required during replication, both the source and the replica servers must support encrypted network connections. If either server does not support encrypted connections (because it has not been compiled or configured for them), replication through an encrypted connection is not possible.
Setting up encrypted connections for replication is similar to doing so for client/server connections. You must obtain (or create) a suitable security certificate that you can use on the source, and a similar certificate (from the same certificate authority) on each replica. You must also obtain suitable key files.
For more information on setting up a server and client for encrypted connections, see Section 6.3.1, “Configuring MySQL to Use Encrypted Connections”.
To enable encrypted connections on the source, you must create or obtain suitable certificate and key files, and then add the following configuration parameters to the source's configuration within the
[mysqld] section of the source's
my.cnf file, changing the file names as necessary:
[mysqld] ssl_ca=cacert.pem ssl_cert=server-cert.pem ssl_key=server-key.pem
The paths to the files may be relative or absolute; we recommend that you always use complete paths for this purpose.
The configuration parameters are as follows:
ssl_ca: The path name of the Certificate Authority (CA) certificate file. (
--ssl-capathis similar but specifies the path name of a directory of CA certificate files.)
ssl_cert: The path name of the server public key certificate file. This certificate can be sent to the client and authenticated against the CA certificate that it has.
ssl_key: The path name of the server private key file.
To enable encrypted connections on the replica, use the
CHANGE MASTER TO statement. You can either name the replica certificate and SSL private key files required for the encrypted connection in the
[client] section of the replica's
my.cnf file, or you can explicitly specify that information using the
CHANGE MASTER TO statement. For more information on the
CHANGE MASTER TO statement, see Section 22.214.171.124, “CHANGE MASTER TO Statement”.
To name the replica certificate and key files using an option file, add the following lines to the
[client]section of the replica's
my.cnffile, changing the file names as necessary:
[client] ssl-ca=cacert.pem ssl-cert=client-cert.pem ssl-key=client-key.pem
Restart the replica server, using the
--skip-slave-startoption to prevent the replica from connecting to the source. Use
CHANGE MASTER TOto specify the source configuration, and add the
MASTER_SSLoption to connect using encryption:
mysql> CHANGE MASTER TO -> MASTER_HOST='source_hostname', -> MASTER_USER='repl', -> MASTER_PASSWORD='password', -> MASTER_SSL=1;
MASTER_SSL=1for a replication connection and then setting no further
MASTER_SSL_options corresponds to setting
--ssl-mode=REQUIREDfor the client, as described in Command Options for Encrypted Connections. With
MASTER_SSL=1, the connection attempt only succeeds if an encrypted connection can be established. A replication connection does not fall back to an unencrypted connection, so there is no setting corresponding to the
--ssl-mode=PREFERREDsetting for replication. If
MASTER_SSL=0is set, this corresponds to
To name the replica certificate and SSL private key files using the
CHANGE MASTER TOstatement, if you did not do this in the replica's
my.cnffile, add the appropriate
-> MASTER_SSL_CA = 'ca_file_name', -> MASTER_SSL_CAPATH = 'ca_directory_name', -> MASTER_SSL_CERT = 'cert_file_name', -> MASTER_SSL_KEY = 'key_file_name',
These options correspond to the
--ssl-options with the same names, as described in Command Options for Encrypted Connections. For these options to take effect,
MASTER_SSL=1must also be set. For a replication connection, specifying a value for either of
MASTER_SSL_CAPATH, or specifying these options in the replica's
my.cnffile, corresponds to setting
--ssl-mode=VERIFY_CA. The connection attempt only succeeds if a valid matching Certificate Authority (CA) certificate is found using the specified information.
To activate host name identity verification, add the
This option corresponds to the
--ssl-verify-server-certoption, which is deprecated as of MySQL 5.7.11 and is removed in MySQL 8.0. For a replication connection, specifying
MASTER_SSL_VERIFY_SERVER_CERT=1corresponds to setting
--ssl-mode=VERIFY_IDENTITY, as described in Command Options for Encrypted Connections. For this option to take effect,
MASTER_SSL=1must also be set. Host name identity verification does not work with self-signed certificates.
To activate certificate revocation list (CRL) checks, add the
-> MASTER_SSL_CRL = 'crl_file_name', -> MASTER_SSL_CRLPATH = 'crl_directory_name',
These options correspond to the
--ssl-options with the same names, as described in Command Options for Encrypted Connections. If they are not specified, no CRL checking takes place.
To specify lists of ciphers and encryption protocols permitted by the replica for the replication connection, add the
-> MASTER_SSL_CIPHER = 'cipher_list', -> MASTER_TLS_VERSION = 'protocol_list',
MASTER_SSL_CIPHERoption specifies the list of ciphers permitted by the replica for the replication connection, with one or more cipher names separated by colons. The
MASTER_TLS_VERSIONoption specifies the encryption protocols permitted by the replica for the replication connection. The format is like that for the
tls_versionsystem variable, with one or more comma-separated protocol versions. The protocols and ciphers that you can use in these lists depend on the SSL library used to compile MySQL. For information about the formats and permitted values, see Section 6.3.2, “Encrypted Connection TLS Protocols and Ciphers”.
After the source information has been updated, start the replication process:
mysql> START SLAVE;
You can use the
SHOW SLAVE STATUSstatement to confirm that an encrypted connection was established successfully.
Requiring encrypted connections on the replica does not ensure that the source requires encrypted connections from replicas. If you want to ensure that the source only accepts replicas that connect using encrypted connections, create a replication user account on the source using the
REQUIRE SSLoption, then grant that user the
REPLICATION SLAVEprivilege. For example:
mysql> CREATE USER 'repl'@'%.example.com' IDENTIFIED BY 'password' -> REQUIRE SSL; mysql> GRANT REPLICATION SLAVE ON *.* -> TO 'repl'@'%.example.com';
If you have an existing replication user account on the source, you can add
REQUIRE SSLto it with this statement:
mysql> ALTER USER 'repl'@'%.example.com' REQUIRE SSL;