Mariadb cannot connect remotely

surroundings

mariadb Ver 15.1 Distrib 10.1.38-MariaDB, for debian-linux-gnu (x86_64) using readline 5.2

Ubuntu 18.04.2

problem

mysql -h 192.168.0.5 -u root -p

The error is as follows:

ERROR 2003 (HY000): Can’t connect to MySQL server on ‘192.168.0.4’ (111 “Connection refused”)

Solution

Refer to the official explanation (true fragrance)
https://mariadb.com/kb/en/library/configuring-mariadb-for-remote-client-access/

1. Comment out the bind-address under /etc/mysql/mariadb.conf.d/50-server.cnf, as shown below:

# 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

2. Permission to write to the database

Enter the mysql command line

GRANT ALL PRIVILEGES ON *.* TO 'USER_NAME'@'%' IDENTIFIED BY 'PASSWORD' WITH GRANT OPTION;

Write USER_NAME, PASSWORD according to your needs.
Be sure to let USER_NAME have all permissions, just a data table is not enough, and then refresh the permissions table.
FLUSH PRIVILEGES;

4. Restart the service
   Be sure to restart mysql\mysql\mariadb

service mysql restart
service mariadb restart
service mysqld restart

5. Have fun

Python script to test whether mariadb is connected

import pymysql

conn = pymysql.Connect(host='192.168.0.2',user='keystone',passwd='keystone1001',db='keystone')
cur = conn.cursor()
cur.execute("select version()")
for i in cur:
    print(i)
cur.close()