MySQL：解决ERROR 2003 (HY000): Can't connect to MySQL server on 'XXX' (111)

摘要：MySQL

想从远程集群上访问本地的MySQL数据库，输入host，用户和密码报错

ERROR 2003 (HY000): Can't connect to MySQL server on 'XXX.XXX.XX.XX' (111)

修改mysqld.cnf

修改mysqld.cnf允许其他机器ip访问。mysqld.cnf目录在/etc/mysql/mysql.conf.d下，如果设置了bind_address=127.0.0.1，只允许本地socket连接，将这一行注释掉

#bind-address           = 127.0.0.1

重启mysqld

service mysql restart

重新连接MySQL继续报错，显示gp用户以host为cloudera01不允许链接

[root@cloudera01 pgeng]# mysql -h192.168.67.72 -ugp -p123456
ERROR 1130 (HY000): Host 'cloudera01' is not allowed to connect to this MySQL server

更改MySQL用户连接权限

更改MySQL用户连接权限使得用户在其他机器有访问权限。打开MySQL mysql库下的user表，查看user和host，gp用户默认host是localhost

mysql -uroot

mysql> select host,user from user;
+-----------+------------------+
| host      | user             |
+-----------+------------------+
| localhost | debian-sys-maint |
| localhost | gp               |
| localhost | mysql.session    |
| localhost | mysql.sys        |
| localhost | root             |
+-----------+------------------+

修改gp用户的host为%

mysql> update user set host='%' where user='gp';
Query OK, 1 row affected (0.05 sec)
Rows matched: 1  Changed: 1  Warnings: 0

赋予全部权限给gp@%，使得gp用户可以在其他机器输入密码连接MySQL

mysql> grant all privileges on *.* to 'gp'@'%';
Query OK, 0 rows affected (0.00 sec)

重启MySQL

service mysql restart

再次在远程集群链接MySQL，登录成功

[root@cloudera01 ubuntu]# mysql -hXXX.XXX.XX.XX -ugp -pXXXXXX
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.7.30-0ubuntu0.18.04.1 (Ubuntu)

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

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

MySQL [(none)]> 

如果是高版本的MySQL8.0，认证方式有所变更，加密规则为caching_sha2_password，而在此之前的加密规则为mysql_native_password，报错如下

[root@ubuntu ~]# mysql -h192.168.67.72 -uroot -p123456 
ERROR 2059 (HY000): Authentication plugin 'caching_sha2_password' cannot be loaded: /usr/lib64/mysql/plugin/caching_sha2_password.so: cannot open shared object file: No such file or directory

可以将加密规则改成mysql_native_password，在本地登录NySQL8.0，修改为mysql_native_password认证如下即可

mysql> ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY '123456';