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