Dovecot with MySQL over SSL.

[John Fawcett]

On 18/07/2019 23:24, Reio Remma via dovecot wrote:
> Hello!
>
> I'm attempting to get Dovecot working with MySQL user database on
> another machine. I can connect to the MySQL (5.7.26) instance with SSL
> enabled:
>
>  mysql -h db.mrst.ee --ssl-ca=/etc/dovecot/ca.pem
> --ssl-cert=/etc/dovecot/client-cert.pem
> --ssl-key=/etc/dovecot/client-key.pem --ssl-cipher=DHE-RSA-AES256-SHA
> -u vmail -p
>
> However if I use the same values in dovecot-sql.conf.ext, I get the
> following error:
>
> Jul 19 00:20:18 turin dovecot: master: Dovecot v2.3.7 (494d20bdc)
> starting up for imap, lmtp, sieve (core dumps disabled)
> Jul 19 00:20:18 turin dovecot: auth-worker(82996): Error:
> mysql(db.mrst.ee): Connect failed to database (vmail): SSL connection
> error: protocol version mismatch - waiting for 1 seconds before retry
> Jul 19 00:20:18 turin dovecot: auth-worker(82996): Error:
> mysql(db.mrst.ee): Connect failed to database (vmail): SSL connection
> error: protocol version mismatch - waiting for 1 seconds before retry
> Jul 19 00:20:19 turin dovecot: auth-worker(82996): Error:
> mysql(db.mrst.ee): Connect failed to database (vmail): Connections
> using insecure transport are prohibited while
> --require_secure_transport=ON. - waiting for 5 seconds before retry
> Jul 19 00:20:19 turin dovecot: auth-worker(82996): Error:
> mysql(db.mrst.ee): Connect failed to database (vmail): Connections
> using insecure transport are prohibited while
> --require_secure_transport=ON. - waiting for 5 seconds before retry
>
> Database connection string:
>
> connect = host=db.mrst.ee dbname=vmail user=vmail password=stuff \
>     ssl_ca=/etc/dovecot/ca.pem \
>     ssl_cert=/etc/dovecot/client-cert.pem \
>     ssl_key=/etc/dovecot/client-key.pem \
>     ssl_cipher=DHE-RSA-AES256-SHA
>
> If I leave the ssl_cipher unset, I get:
>
> Jul 19 00:23:41 turin dovecot: auth-worker(83069): Error:
> mysql(db.mrst.ee): Connect failed to database (vmail): SSL connection
> error: Failed to set ciphers to use - waiting for 1 seconds before retry
>
> Any ideas?
>
> Thanks!
> Reio

One difference between your testing manually with mysql client and the
same configuration in dovecot is the "ssl_verify_server_cert" parameter.
Dovecot is setting it if it is not specified. So to make the tests the
same you should either specify the --ssl_verify_server_cert parameter to
mysql or set it to no in the dovecot configuration.

John