ERROR 2049 (HY000): Connection using old (pre-4.1.1)

    测试环境新装了MySQL服务器，在登陆时无法成功登陆。其提示为使用的旧的认证协议而被拒绝。其具体的错误提示为ERROR 2049 (HY000): Connection using old (pre-4.1.1) authentication protocol refused (client option 'secure_auth' enabled)以下是关于这个问题的描述及其解决方案，供大家参考。

1、故障现象
[root@HKBO ~]# mysqladmin -u root password 'Mysqlxxx'
[root@HKBO ~]# mysql -uroot -p
Enter password:
ERROR 2049 (HY000): Connection using old (pre-4.1.1) authentication protocol refused (client option 'secure_auth' enabled)

[root@HKBO ~]# mysql -uroot -p --skip-secure-auth
Enter password:
ERROR 1275 (HY000): Server is running in --secure-auth mode, but 'root'@'localhost' has a password in the old format; please change the password to the new format

2、有关secure_auth参数

•  --secure-auth

  Command-Line Format	--secure-auth
  System Variable	Name	secure_auth
  	Variable Scope	Global
  	Dynamic Variable	Yes
  Permitted Values (<= 5.6.4)	Type	boolean
  	Default	OFF
  Permitted Values (>= 5.6.5)	Type	boolean
  	Default	ON

  This option causes the server to block connections by clients that attempt to use accounts that have passwords stored in the old (pre-4.1) format. Use it to prevent all use of passwords employing the old format (and hence insecure communication over the network). Before MySQL 5.6.5, this option is disabled by default. As of MySQL 5.6.5, it is enabled by default; to disable it, use --skip-secure-auth.

  Server startup fails with an error if this option is enabled and the privilege tables are in pre-4.1 format. SeeSection B.5.2.4, “Client does not support authentication protocol”.

  The mysql client also has a --secure-auth option, which prevents connections to a server if the server requires a password in old format for the client account.

  Note

  Passwords that use the pre-4.1 hashing method are less secure than passwords that use the native password hashing method and should be avoided. Pre-4.1 passwords are deprecated and support for them will be removed in a future MySQL release. Consequently, disabling secure authentication using --skip-secure-auth is also deprecated.

3、分析及解决

#查看当前的配置文件
[root@HKBO ~]# grep -v ^# /etc/my.cnf 
[mysqld]
datadir=/opt/data
socket=/tmp/mysql.sock
user=mysql
old_passwords=1   

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

#old_passwords
#This variable controls the password hashing method used by the PASSWORD() function.
#It also influences password hashing performed by CREATE USER and GRANT statements that specify a password using an IDENTIFIED BY clause.
#当值为1的使用正好使用的是Pre-4.1 (“old”) hashing mysql_old_password 旧密码方式，因此先将其禁用

[root@HKBO ~]# vi /etc/my.cnf

#如下，禁用后的old_passwords
[root@HKBO ~]# grep old_passwords /etc/my.cnf 
#old_passwords=1

#重启mysql
[root@HKBO ~]# service mysqld stop
Shutting down MySQL.[  OK  ]

[root@HKBO ~]# service mysqld start
Starting MySQL..[  OK  ]

#登陆还是出现同样的提示
[root@HKBO ~]# mysql -uroot -p
Enter password: 
ERROR 2049 (HY000): Connection using old (pre-4.1.1) authentication protocol refused (client option 'secure_auth' enabled)

#下面尝试使用--secure_auth=off登陆，提示需要改变密码到新格式
[root@HKBO ~]# mysql -uroot -p --secure_auth=off
Enter password: 
ERROR 1275 (HY000): Server is running in --secure-auth mode, but 'root'@'localhost' has a password in the old format; please change the password to the new format

#下面我们增加secure-auth=off到配置文件
[root@HKBO ~]# grep secure-auth /etc/my.cnf
secure-auth=off

#再次重启mysql
[root@HKBO ~]# service mysqld stop
Shutting down MySQL.[  OK  ]
[root@HKBO ~]# service mysqld start
Starting MySQL.[  OK  ]

#此时可以透过--secure_auth=off方式登陆
[root@HKBO ~]# mysql -uroot -p --secure_auth=off
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.6.12 Source distribution

Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> set password for 'root'@'localhost' =password('Mysqlxxx');
Query OK, 0 rows affected, 1 warning (0.01 sec)

mysql> exit
Bye

#通过上述操作后还是无法登陆，依旧需要使用--secure_auth=off方式才能登陆

#查看缺省的mysql客户端
[root@HKBO ~]# which mysql
/app/soft/mysql/bin/mysql

[root@HKBO ~]# /app/soft/mysql/bin/mysql -uroot -p
Enter password: 
ERROR 2049 (HY000): Connection using old (pre-4.1.1) authentication protocol refused (client option 'secure_auth' enabled)

[root@HKBO ~]# /app/soft/mysql/bin/mysql --version
/app/soft/mysql/bin/mysql  Ver 14.14 Distrib 5.6.12, for Linux (x86_64) using  EditLine wrapper

[root@HKBO ~]# whereis mysql
mysql: /usr/bin/mysql /usr/share/mysql /usr/share/man/man1/mysql.1.gz

#/usr/bin下也有一个mysql客户端，其版本为5.0.95
[root@HKBO ~]# /usr/bin/mysql --version
/usr/bin/mysql  Ver 14.12 Distrib 5.0.95, for redhat-linux-gnu (x86_64) using readline 5.1

#经排查，当前主机有旧版的mysql
[root@HKBO mysql]# rpm -qa | grep -i mysql
mysql-5.0.95-3.el5

#接下来卸载老版本的mysql
[root@HKBO ~]# rpm -e --nodeps mysql-5.0.95-3.el5
warning: /etc/my.cnf saved as /etc/my.cnf.rpmsave

[root@HKBO ~]# find / -name mysql
/usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/DBD/mysql
/usr/lib64/perl5/vendor_perl/5.8.8/x86_64-linux-thread-multi/auto/DBD/mysql
               .........
/app/soft/mysql
/app/soft/mysql/bin/mysql
/app/soft/mysql/include/mysql
/var/lib/mysql
/var/spool/mail/mysql
/opt/data/mysql
/home/mysql
#移除旧版mysql的路径及其文件
[root@HKBO ~]# rm -rf /var/lib/mysql   

#考虑到配置文件的为旧版，直接用5.6.12版的缺省配置文件覆盖
[root@HKBO ~]# cp /app/soft/mysql/support-files/my-default.cnf /etc/my.cnf
[root@HKBO ~]# grep -v ^# /etc/my.cnf
[mysqld]
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES 

#重启mysql
[root@HKBO ~]# service mysqld stop
Shutting down MySQL..[  OK  ]
[root@HKBO ~]# service mysqld start
Starting MySQL.[  OK  ]

[root@HKBO ~]# mysql -uroot -p --secure_auth=off
Enter password: 

mysql> select user,host,password from mysql.user;
+------+--------------+------------------+   # Author : Leshami
| user | host         | password         |   # Blog   : http://blog.csdn.net/leshami
+------+--------------+------------------+
| root | localhost    | 7ca9a8e40dd1bf23 |   #可以看到加密后的密码为16bit
+------+--------------+------------------+

mysql> set password for 'root'@'localhost'=password('Mysql66');
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> select user,host,password from mysql.user where user='root';
+------+--------------+------------------+
| user | host         | password         |
+------+--------------+------------------+
| root | localhost    | 5614c1a44e6b0c87 |  #更新后还是16bit
+------+--------------+------------------+

#接下来尝试清空root密码
mysql> update mysql.user set password='' where user='root' and host='localhost';
Query OK, 1 row affected (0.02 sec)
Rows matched: 1  Changed: 1  Warnings: 0

#再一次重启mysql
[root@HKBO ~]# service mysqld stop
Shutting down MySQL.[  OK  ]
[root@HKBO ~]# service mysqld start
Starting MySQL.[  OK  ]

#接下来使用mysqladmin修改密码
[root@HKBO ~]# mysqladmin -u root password 'xxx'

#此时可以成功登陆，且密码的密文明显变长，至此问题解决
[root@HKBO ~]# mysql -uroot -p
Enter password: 

mysql> select user,password,host from mysql.user;
+------+-------------------------------------------+--------------+
| user | password                                  | host         |
+------+-------------------------------------------+--------------+
| root | *3D56A309CD04FA2EEF181462E59011F075C89548 | localhost    |
+------+-------------------------------------------+--------------+

4、小结
a、绝大多数情况下，MySQL缺省的my.cnf不靠谱，根据情况都需要适度修改。
b、在安装MySQL之前应先检查当前主机是否存在旧版以及多实例(此次由于非生产环境，所以疏忽导致了这个问题)
c、根据错误提示来定位故障原因，如此次的关键字为secure_auth
d、理解有关secure_auth,old_passwords,skip-secure-auth参数的作用及其影响