问题描述

1. 第一步：检查网络配置呗，能不能ping上客户机。（跳过）

2. 第二步：客户机上的mysql没启动：systemctl status mysqld

   [root@localhost mysql]# systemctl status mysqld
   ● mysqld.service - MySQL Server
      Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
      Active: active (running) since 四 2022-10-13 06:01:00 UTC; 41min ago
        Docs: man:mysqld(8)
              http://dev.mysql.com/doc/refman/en/using-systemd.html
     Process: 10500 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
     Process: 10479 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
    Main PID: 10503 (mysqld)
       Tasks: 28
      CGroup: /system.slice/mysqld.service
              └─10503 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
   
   10月 13 06:01:00 localhost.localdomain systemd[1]: Stopped MySQL Server.
   10月 13 06:01:00 localhost.localdomain systemd[1]: Starting MySQL Server...
   10月 13 06:01:00 localhost.localdomain systemd[1]: Started MySQL Server.
   

3. 第三步：防火墙上的3306端口没开放，查一下：ss -lnt

   [root@localhost mysql]# ss -lnt
   State      Recv-Q Send-Q                                                             Local Address:Port                                                                            Peer Address:Port              
   LISTEN     0      128                                                                            *:111                                                                                        *:*                  
   LISTEN     0      128                                                                            *:6000                                                                                       *:*                  
   LISTEN     0      5                                                                  192.168.122.1:53                                                                                         *:*                  
   LISTEN     0      128                                                                            *:22                                                                                         *:*                  
   LISTEN     0      128                                                                    127.0.0.1:631                                                                                        *:*                  
   LISTEN     0      100                                                                    127.0.0.1:25                                                                                         *:*                  
   LISTEN     0      128                                                                    127.0.0.1:6010                                                                                       *:*                  
   LISTEN     0      80                                                                            :::3306                                                                                      :::*                  
   LISTEN     0      128                                                                           :::111                                                                                       :::*                  
   LISTEN     0      128                                                                           :::6000                                                                                      :::*                  
   LISTEN     0      128                                                                           :::22                                                                                        :::*                  
   LISTEN     0      128                                                                          ::1:631                                                                                       :::*                  
   LISTEN     0      100                                                                          ::1:25                                                                                        :::*                  
   LISTEN     0      128                                                                          ::1:6010                                                                                      :::*                  
   

4. 3306端口开了，但是3306端口没有被监听！（我的问题就是这），所以，先添加需要监听的端口：

   [root@localhost mysql]# firewall-cmd --permanent --zone=public --add-port=3306/tcp
   Warning: ALREADY_ENABLED: 3306:tcp
   success
   [root@localhost mysql]# firewall-cmd --permanent --zone=public --add-port=3306/tcp
   Warning: ALREADY_ENABLED: 3306:tcp
   success
   
   

5. 加了3306端口之后可以测一下了，如果显示不允许连接，那么开启mysql ，使用root登录，进入mysql数据库，查询mysql.user这张表，可以看到HOST,是localhost，表示只能本地登录mysql，

   mysql> use mysql
   Reading table information for completion of table and column names
   You can turn off this feature to get a quicker startup with -A
   
   Database changed
   mysql> select User,HOST from mysql.user;
   +---------------+-----------+
   | User          | HOST      |
   +---------------+-----------+
   | mysql.session | localhost |
   | mysql.sys     | localhost |
   | root          | localhost |
   +---------------+-----------+
   3 rows in set (0.00 sec)
   
   

6. 增加远程访问权限，%百分号表示允许任何IP访问数据库，并刷新：flush privileges;,再重启下mysql数据库，接下来就可以正常登录了

   mysql> grant all privileges on *.* to root@"%" identified by "1234566";
   Query OK, 0 rows affected, 1 warning (0.00 sec)
   
   mysql> flush privileges;
   Query OK, 0 rows affected (0.00 sec)
   
   mysql> select User,HOST from mysql.user;
   +---------------+-----------+
   | User          | HOST      |
   +---------------+-----------+
   | root          | %         |
   | mysql.session | localhost |
   | mysql.sys     | localhost |
   | root          | localhost |
   +---------------+-----------+
   4 rows in set (0.00 sec)
   
   mysql> systemctl restart mysqld