The current implementation of the authentication protocol uses a password hashing algorithm that is incompatible with that used by older (pre-4.1) clients. Attempts to connect to a 4.1 or higher server with an older client may fail with the following message:
$> mysql
Client does not support authentication protocol requested
by server; consider upgrading MySQL client
To deal with this problem, the preferred solution is to upgrade all client programs to use a 4.1.1 or higher client library. If that is not possible, use one of the following approaches:
To connect to the server with a pre-4.1 client program, use an account that still has a pre-4.1-style password.
Reset the password to pre-4.1 style for each user that needs to use a pre-4.1 client program. This can be done using the
SET PASSWORD
statement and theOLD_PASSWORD()
function. As of MySQL 5.6.6, it is also necessary to first ensure that the authentication plugin for the account ismysql_old_password
:mysql> UPDATE mysql.user SET plugin = 'mysql_old_password' mysql> WHERE User = 'some_user' AND Host = 'some_host'; mysql> FLUSH PRIVILEGES; mysql> SET PASSWORD FOR -> 'some_user'@'some_host' = OLD_PASSWORD('new_password');
Substitute the password you want to use for “
new_password
” in the preceding example. MySQL cannot tell you what the original password was, so you'll need to pick a new one.Tell the server to use the older password hashing algorithm by default:
Start mysqld with the
old_passwords
system variable set to 1.Assign an old-format password to each account that has had its password updated to the longer 4.1 format. You can identify these accounts with the following query:
mysql> SELECT Host, User, Password FROM mysql.user -> WHERE LENGTH(Password) > 16;
For each account record displayed by the query, use the
Host
andUser
values and assign a password using one of the methods described previously.
The Client does not support authentication
protocol
error also can occur if multiple versions
of MySQL are installed but client programs are dynamically
linked and link to an older library. Make sure that clients
use the most recent library version with which they are
compatible. The procedure to do this depends on your system.
The PHP mysql
extension does not support
the authentication protocol in MySQL 4.1.1 and higher. This
is true regardless of the PHP version being used. If you
wish to use the mysql
extension with
MySQL 4.1 or higher, you may need to follow one of the
options discussed above for configuring MySQL to work with
old clients. The mysqli
extension (stands
for "MySQL, Improved"; added in PHP 5) is compatible with
the improved password hashing employed in MySQL 4.1 and
higher, and no special configuration of MySQL need be done
to use this MySQL client library. For more information about
the mysqli
extension, see
http://php.net/mysqli.
For additional background on password hashing and authentication, see Section 6.1.2.4, “Password Hashing in MySQL”.