MySQL 服务器位于central.hwcharts.com；它是基本主从复制的主服务器，该复制朝向host0.hwcharts.com，位于不同的物理机器上，该物理机器虚拟化（OpenVZ）从服务器运行的 VM。
复制本身工作正常，但问题是从“从属”机器启动的 mysql-client 无法连接到主机器：
mysql -h central.hwcharts.com -u hwcharts -pvery-long-pass hwcharts
ERROR 2003 (HY000): Can't connect to MySQL server on 'central.hwcharts.com' (111)
从另外两台通用机器执行的相同命令运行正常，并成功连接到主数据库。图片上的详细信息：
+-------------------------------------------------------------------------------+
+--------------------+ | host0.hwcharts.com |
|central.hwcharts.com| |-------------------------------------------------------------------------------|
|--------------------| | |
| | | +-----+ +--------+ +--------------------------------------------+ |
| MySQL master |-------->| NAT |--+-->| OpenVZ |--+-->| MySQL slave host | |
| | | +-----+ | +--------+ | | MySQL-client cannot reach master from here | |
+--------------------+ | | | +--------------------------------------------+ |
| | | +--------------------------------------------+ |
| | | | Another generic VM | |
| | +-->| MySQL-client can reach master from here | |
| | +--------------------------------------------+ |
| | |
| | +-----------------------------------------+ |
| | | Generic physical computer | |
| +-->| MySQL-client can reach master from here | |
| +-----------------------------------------+ |
| |
+-------------------------------------------------------------------------------+
central.hwcharts.com是一个租用的 VPS；host0.hwcharts.com而是将 IP 映射到我的家用调制解调器。
每台机器上的 MySQL 版本均为 5.5.31，包括客户端和服务器软件。
操作系统包括：
central.hwcharts.com：Debian 6.0.4host0.hwcharts.com（每个 OpenVZ VM）：Debian 7.1host0.hwcharts.com（通用计算机）：Debian 6.0.3
配置文件：
在主服务器上，/etc/mysql/my.cnf包含：
#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
#
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html
# This will be passed to all mysql clients
# It has been reported that passwords should be enclosed with ticks/quotes
# escpecially if they contain "#" chars...
# Remember to edit /etc/mysql/debian.cnf when changing the socket location.
[client]
port = 3306
socket = /var/run/mysqld/mysqld.sock
# Here is entries for some specific programs
# The following values assume you have at least 32M ram
# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket = /var/run/mysqld/mysqld.sock
nice = 0
[mysqld]
#
# * Basic Settings
#
user = mysql
pid-file = /var/run/mysqld/mysqld.pid
socket = /var/run/mysqld/mysqld.sock
port = 3306
basedir = /usr
datadir = /var/lib/mysql
tmpdir = /tmp
language = /usr/share/mysql/english
skip-external-locking
#
# 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
#
# * Fine Tuning
#
key_buffer = 16M
max_allowed_packet = 16M
thread_stack = 192K
thread_cache_size = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover = BACKUP
#max_connections = 100
#table_cache = 64
#thread_concurrency = 10
#
# * Query Cache Configuration
#
query_cache_limit = 1M
query_cache_size = 16M
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file = /var/log/mysql/mysql.log
#general_log = 1
#
# Error logging goes to syslog due to /etc/mysql/conf.d/mysqld_safe_syslog.cnf.
#
# Here you can see queries with especially long duration
#log_slow_queries = /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
# other settings you may need to change.
server-id = 1
log_bin = /var/log/mysql/mysql-bin.log
expire_logs_days = 14
max_binlog_size = 100M
innodb_flush_log_at_trx_commit = 1
sync_binlog = 1
#binlog_do_db = include_database_name
binlog_ignore_db = greatturn
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
innodb_file_per_table
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem
[mysqldump]
quick
quote-names
max_allowed_packet = 16M
[mysql]
#no-auto-rehash # faster start of mysql but no tab completition
[isamchk]
key_buffer = 16M
#
# * IMPORTANT: Additional settings that can override those from this file!
# The files must end with '.cnf', otherwise they'll be ignored.
#
!includedir /etc/mysql/conf.d/
在从服务器上，/etc/mysql/my.cnf 包含：
#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
#
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html
# This will be passed to all mysql clients
# It has been reported that passwords should be enclosed with ticks/quotes
# escpecially if they contain "#" chars...
# Remember to edit /etc/mysql/debian.cnf when changing the socket location.
[client]
port = 3307
socket = /var/run/mysqld/mysqld.sock
# Here is entries for some specific programs
# The following values assume you have at least 32M ram
# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket = /var/run/mysqld/mysqld.sock
nice = 0
[mysqld]
#
# * Basic Settings
#
user = mysql
pid-file = /var/run/mysqld/mysqld.pid
socket = /var/run/mysqld/mysqld.sock
port = 3307
basedir = /usr
datadir = /var/lib/mysql
tmpdir = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
#
# 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
#
# * Fine Tuning
#
key_buffer = 16M
max_allowed_packet = 16M
thread_stack = 192K
thread_cache_size = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover = BACKUP
#max_connections = 100
#table_cache = 64
#thread_concurrency = 10
#
# * Query Cache Configuration
#
query_cache_limit = 1M
query_cache_size = 16M
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file = /var/log/mysql/mysql.log
#general_log = 1
#
# Error logging goes to syslog due to /etc/mysql/conf.d/mysqld_safe_syslog.cnf.
#
# Here you can see queries with especially long duration
#log_slow_queries = /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
# other settings you may need to change.
server-id = 2
#log_bin = /var/log/mysql/mysql-bin.log
expire_logs_days = 10
max_binlog_size = 100M
#binlog_do_db = include_database_name
#binlog_ignore_db = include_database_name
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
innodb_file_per_table
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem
[mysqldump]
quick
quote-names
max_allowed_packet = 16M
[mysql]
#no-auto-rehash # faster start of mysql but no tab completition
[isamchk]
key_buffer = 16M
#
# * IMPORTANT: Additional settings that can override those from this file!
# The files must end with '.cnf', otherwise they'll be ignored.
#
!includedir /etc/mysql/conf.d/
其他：
select user,host,password from mysql.user;
+------------------+-----------+-------------------------------------------+
| user | host | password |
+------------------+-----------+-------------------------------------------+
| root | localhost | *non-null-hash-replaced-xxxxxxxxxxxxxxxxx |
| debian-sys-maint | localhost | *non-null-hash-replaced-xxxxxxxxxxxxxxxxx |
| greatturn | localhost | |
| replication | % | *non-null-hash-replaced-xxxxxxxxxxxxxxxxx |
| hwcharts | % | *non-null-hash-replaced-xxxxxxxxxxxxxxxxx |
+------------------+-----------+-------------------------------------------+
答案1
您需要覆盖在从属计算机的 my.cnf 部分中配置的非标准端口 3307。[client]您正尝试连接到主服务器上的端口 3307，该端口配置为侦听 3306，这就是您收到错误 111 - 连接被拒绝的原因。将其添加到您的 mysql 命令行客户端调用中：
--port=3306
它可以在其他机器上运行，因为它们没有非标准配置。
答案2
尝试在语句中指定主机掩码，GRANT如下所示：
grant ALL PRIVILEGES on hwcharts.* to hwcharts@'host0.hwcharts.com' IDENTIFIED BY 'ultrasecret';
如果这没有帮助，提供输出
mysql> select user,host from mysql.user;
可能会对这个问题有所启发。