一、生产环境：
服务器端操作系统：CentOS Linux 6.6
客户端操作系统: CentOS Linux 6.7
数据库系统：mysql 5.5.41
二、生产任务：远程连接MySQL数据库
三、操作过程（包括一些异常情况）：
1.在客户端连服务端的情况
[root@jxatei ~]# mysql -h 117.40.239.9 -u root -p
Enter password:
ERROR 1130(HY000): Host '115.151.218.186' is not allowed to connect to this MySQL server
说明：服务器端不充许IP:“115.151.218.186”连服务端。
2.在服务器端加入客户端IP“115.151.218.186”
mysql> GRANTALL PRIVILEGES ON *.* TO 'root'@'115.151.218.186' IDENTIFIED BY 'root' WITH GRANT OPTION;
Query OK, 0 rows affected (0.01 sec)
3.客户端再次连接
[root@jxatei ~]# mysql -h 117.40.239.9 -u root -p
Enter password:
ERROR 1045 (28000): Access denied for user'root'@'115.151.218.186' (using password: YES)
4.服务端修改
[root@sky9896etc]# vi my.cnf
[mysqld]
skip-grant-tables #在[mysqld]中加该条命令
#在启动mysql时不启动grant-tables，授权表。有什么用呢？当然是忘记管理员密码后有用或是其它用途，此次操作是想解决远程连不上服务端。
[root@sky9896etc]# service mysqld stop
停止 mysqld： [确定]
[root@sky9896etc]# service mysqld start
*** glibc detected*** /usr/libexec/mysqld: double free or corruption (fasttop):0x00007f7ab4004a40 ***
正在启动 mysqld： [确定]
[root@sky9896etc]# ======= Backtrace: =========
/lib64/libc.so.6(+0x75e66)[0x7f7ad3b5ce66]
/usr/libexec/mysqld(_ZN16Security_context7destroyEv+0xb4)[0x5623a4]
/usr/libexec/mysqld(_ZN3THDD1Ev+0x13d)[0x565f1d]
/usr/libexec/mysqld(_ZN3THDD0Ev+0x9)[0x5662f9]
/usr/libexec/mysqld(_Z10unlink_thdP3THD+0xfa)[0x5184ea]
/usr/libexec/mysqld(_Z29one_thread_per_connection_endP3THDb+0x16)[0x518556]
/usr/libexec/mysqld(_Z24do_handle_one_connectionP3THD+0x139)[0x6208f9]
/usr/libexec/mysqld(handle_one_connection+0x5b)[0x6209db]
/lib64/libpthread.so.0(+0x79d1)[0x7f7ad56cb9d1]
/lib64/libc.so.6(clone+0x6d)[0x7f7ad3bcf9dd]
======= Memorymap: ========
00400000-00c71000r-xp 00000000 08:02 530781 /usr/libexec/mysqld
00e70000-00f88000rw-p 00870000 08:02 530781 /usr/libexec/mysqld
00f88000-00fb1000rw-p 00000000 00:00 0
01443000-01df1000rw-p 00000000 00:00 0 [heap]
7f7ab4000000-7f7ab4021000rw-p 00000000 00:00 0
7f7ab4021000-7f7ab8000000---p 00000000 00:00 0
7f7abb447000-7f7abb448000---p 00000000 00:00 0
7f7abb448000-7f7abbe48000rw-p 00000000 00:00 0
7f7abbe48000-7f7abbe49000---p 00000000 00:00 0
7f7abbe49000-7f7abc849000rw-p 00000000 00:00 0
7f7abc849000-7f7abc84a000---p 00000000 00:00 0
7f7abc84a000-7f7abd24a000rw-p 00000000 00:00 0
7f7abd24a000-7f7abd24b000---p 00000000 00:00 0
7f7abd24b000-7f7abded9000rw-p 00000000 00:00 0
7f7abe2f7000-7f7abe2f8000---p 00000000 00:00 0
7f7abe2f8000-7f7abecf8000rw-p 00000000 00:00 0
7f7abecf8000-7f7abecf9000---p 00000000 00:00 0
7f7abecf9000-7f7abf6f9000rw-p 00000000 00:00 0
…………………………………………………….
#MySQL启动过程出现以上情况
[root@sky9896etc]# mysql -u root mysql
ERROR 1044(42000): Access denied for user ''@'localhost' to database 'mysql'
[root@sky9896etc]# mysql -u root
Welcome to theMySQL monitor. Commands end with ; or\g.
Your MySQLconnection id is 3
Server version:5.5.41-cll-lve MySQL Community Server (GPL) by Atomicorp
Copyright (c)2000, 2014, Oracle and/or its affiliates. All rights reserved.
Oracle is aregistered trademark of Oracle Corporation and/or its
affiliates. Othernames may be trademarks of their respective
owners.
Type 'help;' or'\h' for help. Type '\c' to clear the current input statement.
mysql> UPDATEuser SET Password=PASSWORD(’sky9890’) where USER=’root’;
ERROR 1046(3D000): No database selected
mysql> usemysql
ERROR 1044(42000): Access denied for user ''@'localhost' to database 'mysql'
mysql> showdatabases;
+--------------------+
| Database |
+--------------------+
|information_schema |
+--------------------+
1 row in set (0.00sec)
mysql> showdatabases;
+--------------------+
| Database |
+--------------------+
|information_schema |
+--------------------+
1 row in set (0.00sec)
mysql> FLUSHPRIVILEGES;
ERROR 1227(42000): Access denied; you need (at least one of) the RELOAD privilege(s) forthis operation
mysql> quit
Bye
[root@sky9896etc]# mysql -u root
Welcome to theMySQL monitor. Commands end with ; or\g.
Your MySQLconnection id is 7
Server version:5.5.41-cll-lve MySQL Community Server (GPL) by Atomicorp
Copyright (c)2000, 2014, Oracle and/or its affiliates. All rights reserved.
Oracle is aregistered trademark of Oracle Corporation and/or its
affiliates. Othernames may be trademarks of their respective
owners.
Type 'help;' or'\h' for help. Type '\c' to clear the current input statement.
mysql> showdatabases;
+--------------------+
| Database |
+--------------------+
|information_schema |
+--------------------+
1 row in set (0.00sec)
#因为增加了一条“skip-grant-tables”语句，登录mysql数据库不需要密码，最终导致mysql服务器中没有数据库了。当然客户端还是连不上，因目前服务端本身找不到数据库了。
[root@jxatei~]# mysql -u root -h 117.40.239.9 -p 3306
Enterpassword:
ERROR1049 (42000): Unknown database '3306'
[sky@sky9896~]$ mysql -u root -p
Enterpassword:
ERROR2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock'(2)
[sky@sky9896~]$ service mysqld start
touch:无法创建"/var/log/mysqld.log":权限不够
chown:正在更改"/var/log/mysqld.log"的所有者: 不允许的操作
chmod:更改"/var/log/mysqld.log"的权限: 不允许的操作
chown:正在更改"/var/lib/mysql"的所有者: 不允许的操作
chmod:更改"/var/lib/mysql"的权限: 不允许的操作
MySQLDaemon failed to start.
正在启动 mysqld： [失败]
[sky@sky9896~]$ su - root
密码：
[root@sky9896~]# service mysqld status
mysqld已停
[root@sky9896~]# service mysqld start
正在启动 mysqld： [确定]
[root@sky9896~]# service mysqld restart
停止 mysqld： [确定]
正在启动 mysqld： [确定]
------------------空密码登录----------------------------------
[root@sky9896~]# mysql -u root
Welcometo the MySQL monitor. Commands end with; or \g.
YourMySQL connection id is 2
Serverversion: 5.5.41-cll-lve MySQL Community Server (GPL) by Atomicorp
Copyright(c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
Oracleis a registered trademark of Oracle Corporation and/or its
affiliates.Other names may be trademarks of their respective
owners.
Type'help;' or '\h' for help. Type '\c' to clear the current input statement.
------------只是匿名登录，无法打开mysql本地数据库---------
mysql>use mysql
ERROR1044 (42000): Access denied for user ''@'localhost' to database 'mysql'
mysql>use mysql;
ERROR1044 (42000): Access denied for user ''@'localhost' to database 'mysql'
mysql>exit
Bye
[root@sky9896~]# service mysqld stop
停止 mysqld： [确定]
------以命令行参数启动mysql，不启动grant-tables，授权表，以重新设置密码---
[root@sky9896~]# mysqld_safe --skip-grant-tables
15081110:53:31 mysqld_safe Logging to '/var/log/mysqld.log'.
15081110:53:31 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
---------------登录，重新设置密码――――――――――――――――
[root@sky9896~]# mysql
Welcometo the MySQL monitor. Commands end with; or \g.
YourMySQL connection id is 1
Serverversion: 5.5.41-cll-lve MySQL Community Server (GPL) by Atomicorp
Copyright(c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
Oracleis a registered trademark of Oracle Corporation and/or its
affiliates.Other names may be trademarks of their respective
owners.
Type'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>use mysql
Readingtable information for completion of table and column names
Youcan turn off this feature to get a quicker startup with -A
Databasechanged
mysql>update user set password=password("sky9890") whereuser="root";
QueryOK, 1 row affected (0.00 sec)
Rowsmatched: 5 Changed: 1 Warnings: 0
mysql>flush privileges;
QueryOK, 0 rows affected (0.00 sec)
mysql>show databases;
+--------------------+
|Database |
+--------------------+
|information_schema |
|back20150625ultrax |
|feifeicms |
|mysql |
|performance_schema |
|ultrax |
+--------------------+
6rows in set (0.00 sec)
mysql>
[root@sky9896~]# service mysqld start
MySQLDaemon failed to start.
正在启动 mysqld： [失败]
[root@sky9896~]# shutdown - r now #重启服务器
[root@sky9896~]# service mysqld status #运行正常了
mysqld(pid 1239) 正在运行...
#但论坛无法正常运行，显示情况如下：
Discuz! Database Error |
The database has encountered a problem. Need Help? |
|
|
Error messages: |
|
Program messages: |
|
|
mysql>use mysql |
ERROR1044 (42000): Access denied for user ''@'localhost' to database 'mysql'
mysql>show databases;
+--------------------+
|Database |
+--------------------+
|information_schema |
+--------------------+
1row in set (0.00 sec)
#原因是匿名登录，没有真正登录，导致客户端无法连上数据库服务器中的数据库。
mysql>show databases;
ERROR2006 (HY000): MySQL server has gone away
Noconnection. Trying to reconnect...
Connectionid: 1
Currentdatabase: *** NONE ***
+--------------------+
|Database |
+--------------------+
|information_schema |
|back20150625ultrax |
|feifeicms |
|mysql |
|performance_schema |
|test |
|ultrax |
+--------------------+
7rows in set (0.00 sec)
mysql>update user set password=password("sky9890") whereuser="root";
ERROR2006 (HY000): MySQL server has gone away
Noconnection. Trying to reconnect...
ERROR2002 (HY000): Can't connect to local MySQL server through socket'/var/lib/mysql/mysql.sock' (2)
ERROR:
Can'tconnect to the server
mysql>use mysql
No connection. Trying to reconnect...
Connection id: 1
Current database: *** NONE ***
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Databasechanged
mysql>update user set password=password("sky9890") whereuser="root";
QueryOK, 0 rows affected (0.00 sec)
Rowsmatched: 6 Changed: 0 Warnings: 0
mysql>flush privileges;
QueryOK, 0 rows affected (0.00 sec)
#以上代码执行后，发现还是存在问题，无法更新空密码。
[sky@sky9896 ~]$ mysql �CA #加-A参数解决问题
Welcometo the MySQL monitor. Commands end with; or \g.
YourMySQL connection id is 1
Serverversion: 5.5.41-cll-lve MySQL Community Server (GPL) by Atomicorp
Copyright(c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
Oracleis a registered trademark of Oracle Corporation and/or its
affiliates.Other names may be trademarks of their respective owners.
Type'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>show databases;
+--------------------+
|Database |
+--------------------+
|information_schema |
|back20150625ultrax |
|feifeicms |
|mysql |
|performance_schema |
|test |
|ultrax |
+--------------------+
7rows in set (0.00 sec)
mysql>use mysql;
Databasechanged
mysql>update user set password=password("sky9890") whereuser="root";
QueryOK, 0 rows affected (0.00 sec)
Rowsmatched: 6 Changed: 0 Warnings: 0
mysql>flush privileges;
QueryOK, 0 rows affected (0.00 sec)
mysql>exit
Bye
[sky@sky9896~]$ service mysqld restart
cat:/var/run/mysqld/mysqld.pid: 权限不够
停止 mysqld： [失败]
正在启动 mysqld： [确定]
[sky@sky9896~]$ su - root
密码：
[root@sky9896~]# service mysqld restart
停止 mysqld： [确定]
正在启动 mysqld： [确定]
[root@sky9896~]# mysql
ERROR1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
[root@sky9896~]# mysql -u root -p
Enterpassword:
Welcometo the MySQL monitor. Commands end with; or \g.
YourMySQL connection id is 4
Serverversion: 5.5.41-cll-lve MySQL Community Server (GPL) by Atomicorp
Copyright(c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.
Oracleis a registered trademark of Oracle Corporation and/or its
affiliates.Other names may be trademarks of their respective
owners.
Type'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>
-------无法更新密码，后面是通过mysql �CA 启动方式解决-------------
[root@jxatei/]# mysql -h 117.40.239.9 -u root -p
Enterpassword:
Welcometo the MySQL monitor. Commands end with; or \g.
YourMySQL connection id is 194
Serverversion: 5.5.41-cll-lve MySQL Community Server (GPL) by Atomicorp
Copyright(c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
Oracleis a registered trademark of Oracle Corporation and/or its
affiliates.Other names may be trademarks of their respective
owners.
Type'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>show databases;
+--------------------+
|Database |
+--------------------+
|information_schema |
|back20150625ultrax |
|feifeicms |
|mysql |
|performance_schema |
|test |
|tt |
|ultrax |
+--------------------+
8rows in set (0.01 sec)
小结：远程连接MySQL数据库，要做好几件事情，1，做好grant相关授权；2.不能完全按网络上的抄，例如：服务器端配置的不同，远程连接的方式也稍有不同，例如，我就没有用3306端口，用了3306端口反而连不上；3.使用网络上的资料需要谨慎，一不心会生产更多的问题。
本文出自 “sky9890” 博客，请务必保留此出处http://sky9896.blog.51cto.com/2330653/1683700