How Navicat connects to MySQL on a remote server

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前言：

==Operating environment and tools==

1. Navicat for Mysql

2. One Tencent Cloud lightweight server（Centos 7）

3. Mysql 8.0.24（installed on the remote server）

4. Xshell7（连接操作远程服务器）

一、修改mysqlremote authorization login settings

1、Log in to the database of the remote server（使用Xshell）

mysql -uroot -p    ## 以root登录数据库 
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输入root的登录密码,After success, you will see the following information：

2、查看mysqlThe current default port for the service

use mysql;    ## 选择mysql数据库
select user,host from user;    ## View user access ports
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==说明：rootThe user default islocalhost,Note that only local login is allowedmysql服务.And we're going to take it remotelyroot用户连接数据库,就必须修改host的值,改为**'%'**：允许任何ip访问.==

3.修改host允许任何ip访问

Go ahead and enter the following commands in the command palette：

update user set host = '%' where user = 'root';
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Seeing the above information indicates that the modification is successful！

Then use the previous command again：

select user,host from user;    ## View user access ports
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会看到：root用户的host已经修改为'%'！

==注意：修改完成后 Also need to refresh the service configuration,不然修改不会生效,并且第4step will fail.==

Then type in the command panel：

mysql> FLUSH PRIVILEGES;    ## Refresh service configuration items
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显示Query OK,表示刷新完成.Now we can configure the user permissions we want to log in remotely.

4.授权root用户进行远程登录

输入命令：

mysql> ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY 'root_pwd'; ## 授权root远程登录 后面的root_pwdRepresents the login password
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输入完之后,看到Query OK,说明执行成功！

==说明：This command can authorize any mysql数据库userThe users in the table access the database by remote login,本例中以'root'作为举例,To authorize other users,只需修改'root'The value of the specified user can be used,'root_pwd'为'root'User's corresponding login password,It can be modified to the login password of the user you want to authorize.==

5.启动本地Navicat连接

打开Navicat客户端,新建mysql连接

输入相关信息：

If it shows that the connection is successful,那么恭喜你,The database can be operated remotely

==如果显示2003错误,无法连接上数据库,Please continue to see the operation below==

二、Solve the problem of unable to connect（2003）

1、First make sure that the firewall is allowed3306端口

2、Make sure fire prevention is activated

==未启动==

[[email protected] ~]# firewall-cmd --zone=public --add-port=3306/tcp --permanent
FirewallD is not running

[[email protected] ~]# systemctl status firewalld 
● firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled)
Active: inactive (dead) #Indicates that the fire resistance is not activated
Docs: man:firewalld(1)
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==已启动==

[[email protected] ~]# systemctl start firewalld 

[[email protected] ~]# systemctl status firewalld 
● firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled)
Active: active (running) since Sun 2021-03-07 20:57:40 CST; 9s ago #active (running)Indicates that the firewall is activated
Docs: man:firewalld(1)
Main PID: 29918 (firewalld)
CGroup: /system.slice/firewalld.service
└─29918 /usr/bin/python2 -Es /usr/sbin/firewalld --nofork --nopid
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3、放通防火墙

[[email protected] ~]# firewall-cmd --zone=public --add-port=3306/tcp --permanent
success
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4、Re-add firewall rules

[[email protected] ~]# firewall-cmd --permanent --add-port=3305/tcp
success
[[email protected] ~]# firewall-cmd --reload 
success
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==然后继续使用Navicatto connect==