1.远程端口未开

2.Mysql 数据库中user表

2.1 用户名root 的host字段味更改为% 允许远程访问；

 use mysql;SELECT user,host,plugin,authentication_string FROM user;

user	host	plugin	authentication_string
root	%	auth_socket
debian-sys-maint	localhost	caching_sha2_password	$A$005$
SWNdTeAjySeUwspsURgzyZP4urfCS6gwP5zb5HAZFPZLs0	%c; B_
mysql.infoschema	localhost	caching_sha2_password	$A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED
mysql.session	localhost	caching_sha2_password	$A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED
mysql.sys	localhost	caching_sha2_password	$A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED

2.2 用户名root 的plugin字段未更改为使用密码验证；

auth_socket 值更改为 caching_sha2_password

 ALTER USER 'root'@'%' IDENTIFIED WITH caching_sha2_password BY 'XXXXXXXXXXX';

user	host	plugin	authentication_string
root	%	caching_sha2_password	*7C0C95B5A24D8ED3A3B4A771C6C8E7713D5CEAE1
debian-sys-maint	localhost	caching_sha2_password	$A$005$
SWNdTeAjySeUwspsURgzyZP4urfCS6gwP5zb5HAZFPZLs0	%c; B_
mysql.infoschema	localhost	caching_sha2_password	$A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED
mysql.session	localhost	caching_sha2_password	$A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED
mysql.sys	localhost	caching_sha2_password	$A$005$THISISACOMBINATIONOFINVALIDSALTANDPASSWORDTHATMUSTNEVERBRBEUSED

3. 服务器 中 mysql配置表

通常路径在 /etc/mysql/mysql.conf.d/mysqld.cnf

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

bind-address 配置未配置成 bind-address = 0.0.0.0；