mysql>grant select,insert,update,create on test.* to test@'192.168.8.%' identified by '123456';

mysql>grant select,insert,update,create on test.* to test@'192.168.9.%' identified by '123456';

mysql>grant select,insert,update,create on test.* to test@'192.168.20.%' identified by '123456';

上面的语句表示将test数据库的所有权限授权给test这个用户，只允许test用户在192.168.8/9/20这三个网段的IP范围进行远程登陆，并设置test用户的密码为123456

刷新权限表使其设置生效:
mysql> flush privileges;