今天在升级阿里云服务器MySQL从 5.5到5.7版本时，升级成功后，不能远程访问了，只能在服务器终端访问，折腾了一下午，原来是MySQL配置my.cnf 里边的[mysqld] bind-address=127.0.0.1限制的问题,注释掉就可以了
一、事故现场
使用PHP
// 1.连接数据库
$db_host ="121.29.19.5:3306";
$db_user = "root";
$db_pass = "ali_123456";
$conn = mysql_connect($db_host, $db_user, $db_pass);
if (!$conn)
{
die("Could not connect:" . mysql_error());
}else
{
dump("连接成功！");
}
错误抛出：
Could not connect:Lost connection to MySQL server at 'reading initial communication packet', system error: 111
什么原因呢？后来在网上找了一圈，原来是MySQL配置bind-address限制的问题。
MySQL配置修改
先找到 my.conf 配置文件
find / -name my.conf
cat my.cnf
!includedir /etc/mysql/conf.d/
!includedir /etc/mysql/mysql.conf.d/
最终找到[mysqld]在mysql.conf.d文件夹中：
注释掉即可：bind-address=127.0.0.1
[mysqld]
pid-file = /var/run/mysqld/mysqld.pid
socket = /var/run/mysqld/mysqld.sock
datadir = /var/lib/mysql
log-error = /var/log/mysql/error.log
# By default we only accept connections from localhost
#bind-address = 127.0.0.1
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0