MySQL_远程连接的坑与路

前言：受朋友之托，帮他解决一个远程连接不上mysql的问题，本来想着这是一个很常见的问题，只需要修改下配置文件的，以前也碰到过，但是时间间隔的有点久了，还是有些生疏了，特此记录碰到的一些问题。

1.修改用户登陆权限

1.0.如果记得root密码，此步可以跳过，修改root密码:

1.0.1.停止mysql服务

$ service mysql stop

1.0.2.修改my.cnf文件

查找my.cnf文件在哪里

$ find / -name my.cnf
/etc/mysql/my.cnf

修改my.cnf文件，在文件新增 skip-grant-tables，在启动mysql时不启动grant-tables，授权表

$ vim /etc/mysql/my.cnf
[mysqld]
skip-grant-tables

1.0.3. 启动mysql服务

$ service mysql restart

1.0.4.更改mysql root用户密码

$ mysql
mysql> use mysql;
#更改user表中root用户密码
mysql> update user set authentication_string=PASSWORD("new_pass") where user='root';

1.0.5.再次修改my.cnf文件, 需要把my.cnf配置文件改回去，把skip-grant-tables注释掉就可以了

$ vim /etc/mysql/my.cnf
[mysqld]
# skip-grant-tables

1.0.6.再次重启mysql

$ service mysql restart

用新root密码登录mysql了

1.1.登陆权限简介：

mysql用户设置当中多了一个主机选项，意思是允许这个用户使用什么主机登陆。
一般常见的主机选项为：%，localhost，IP地址
%：任意主机可以登陆
localhost：仅本机可以登陆
IP地址：指定的IP地址可以登陆

1.2.修改root的登陆权限

mysql -u root -p
use mysql;

1.3.修改登陆权限

update db set host = '%' where user = '用户名';
将权限改为ALL PRIVILEGES
mysql> grant all privileges on . to root@'%' identified by "password";

1.4.刷新权限列表

flush privileges;

2.root权限下(su)，修改mysql配置文件(有两处!!!):

2.1. /etc/mysql/mysql.conf.d/mysqld.cnf

[root@my ~]# vi /etc/mysql/mysql.conf.d/mysqld.cnf 
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
#bind-address           = 127.0.0.1    # bind-address = 127.0.0.1注释掉

2.2. 如果安装的是Mariadb10，对应目录文件会发生一些改变,修改/etc/mysql/mariadb.conf.d/50-server.cnf

[root@my ~]# cd /etc/mysql/mariadb.conf.d
[root@my ~]/etc/mysql/mariadb.conf.d# ls
50-client.cnf  50-mysql-clients.cnf  50-mysqld_safe.cnf  50-server.cnf
vi 50-server.cnf    # 同样是注释掉bind-address

2.3. 重启MySQL

[root@my ~]:~# service mysql restart

2.4. 重新远程连接

[root@nb0 ~]# mysql -h xx.xx.xx.xx -uroot -p
Enter password: 
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 10
Server version: 5.7.11-0kord6 (Ubuntu)

Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

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

MySQL [(none)]>

3.几个重点问题：

3.1.

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (111 "Connection refused")

解决方法：打开/etc/mysql/mysql.conf.d/mysqld.cnf, 添加protocol = tcp

vim /etc/mysql/mysql.conf.d/mysqld.cnf

3.2.

Can 't connect to local MySQL server through socket '/tmp/mysql.sock '(2) ";

解决方法：

添加 [client] 配置项，如下所示
配置前：(配置 [client] 前，会报错'/tmp/mysql.sock' (2))

[mysqld]
datadir=/usr/local/mysql/data
basedir=/usr/local/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

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

配置后：(配置 [client] 后，重启 mysql服务)

[mysqld]
datadir=/usr/local/mysql/data
basedir=/usr/local/mysql
socket=/var/lib/mysql/mysql.sock（跟这个socket路径一样）
user=mysql
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

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

[client]
port=3306
socket=/var/lib/mysql/mysql.sock

3.3.

[....] Restarting mysql (via systemctl): mysql.serviceJob for mariadb.service failed                                                                                                       because the control process exited with error code.
See "systemctl status mariadb.service" and "journalctl -xe" for details.
 failed!

解决方法：
不妨使用ll/ls -al来查看一下/var/run/mysqld的所属，如果不都是mysql的话，使用如下命令修改过来。

>ls -al
>chown -R mysql:mysql mysqld/

3.4.

ERROR 1524 (HY000): Plugin 'unix_socket' is not loaded

解决方法：

/etc/init.d/mysql stop
sudo killall mysqld_safe
sudo killall mysqld
sudo mysqld_safe --skip-grant-tables &
mysql -u root
use mysql;
update user set password=PASSWORD("mynewpassword") where User='root';
update user set plugin="mysql_native_password";
quit;
/etc/init.d/mysql stop
sudo kill -9 $(pgrep mysql)
/etc/init.d/mysql start

参考链接：

https://www.cnblogs.com/duanlinxiao/p/10722151.html
https://www.cnblogs.com/jackadam/p/9505562.html#_label0_0
https://blog.csdn.net/chengyuqiang/article/details/70153980
https://blog.csdn.net/luckytanggu/article/details/80251833
https://blog.csdn.net/Homewm/article/details/81628116
https://blog.csdn.net/hjf161105/article/details/78850658
https://blog.csdn.net/u012804180/article/details/80801351
https://www.jb51.net/article/174244.htm